Commit Graph

429 Commits

Author SHA1 Message Date
Linus Torvalds 49d5759268 ARM:
- Provide a virtual cache topology to the guest to avoid
   inconsistencies with migration on heterogenous systems. Non secure
   software has no practical need to traverse the caches by set/way in
   the first place.
 
 - Add support for taking stage-2 access faults in parallel. This was an
   accidental omission in the original parallel faults implementation,
   but should provide a marginal improvement to machines w/o FEAT_HAFDBS
   (such as hardware from the fruit company).
 
 - A preamble to adding support for nested virtualization to KVM,
   including vEL2 register state, rudimentary nested exception handling
   and masking unsupported features for nested guests.
 
 - Fixes to the PSCI relay that avoid an unexpected host SVE trap when
   resuming a CPU when running pKVM.
 
 - VGIC maintenance interrupt support for the AIC
 
 - Improvements to the arch timer emulation, primarily aimed at reducing
   the trap overhead of running nested.
 
 - Add CONFIG_USERFAULTFD to the KVM selftests config fragment in the
   interest of CI systems.
 
 - Avoid VM-wide stop-the-world operations when a vCPU accesses its own
   redistributor.
 
 - Serialize when toggling CPACR_EL1.SMEN to avoid unexpected exceptions
   in the host.
 
 - Aesthetic and comment/kerneldoc fixes
 
 - Drop the vestiges of the old Columbia mailing list and add [Oliver]
   as co-maintainer
 
 This also drags in arm64's 'for-next/sme2' branch, because both it and
 the PSCI relay changes touch the EL2 initialization code.
 
 RISC-V:
 
 - Fix wrong usage of PGDIR_SIZE instead of PUD_SIZE
 
 - Correctly place the guest in S-mode after redirecting a trap to the guest
 
 - Redirect illegal instruction traps to guest
 
 - SBI PMU support for guest
 
 s390:
 
 - Two patches sorting out confusion between virtual and physical
   addresses, which currently are the same on s390.
 
 - A new ioctl that performs cmpxchg on guest memory
 
 - A few fixes
 
 x86:
 
 - Change tdp_mmu to a read-only parameter
 
 - Separate TDP and shadow MMU page fault paths
 
 - Enable Hyper-V invariant TSC control
 
 - Fix a variety of APICv and AVIC bugs, some of them real-world,
   some of them affecting architecurally legal but unlikely to
   happen in practice
 
 - Mark APIC timer as expired if its in one-shot mode and the count
   underflows while the vCPU task was being migrated
 
 - Advertise support for Intel's new fast REP string features
 
 - Fix a double-shootdown issue in the emergency reboot code
 
 - Ensure GIF=1 and disable SVM during an emergency reboot, i.e. give SVM
   similar treatment to VMX
 
 - Update Xen's TSC info CPUID sub-leaves as appropriate
 
 - Add support for Hyper-V's extended hypercalls, where "support" at this
   point is just forwarding the hypercalls to userspace
 
 - Clean up the kvm->lock vs. kvm->srcu sequences when updating the PMU and
   MSR filters
 
 - One-off fixes and cleanups
 
 - Fix and cleanup the range-based TLB flushing code, used when KVM is
   running on Hyper-V
 
 - Add support for filtering PMU events using a mask.  If userspace
   wants to restrict heavily what events the guest can use, it can now
   do so without needing an absurd number of filter entries
 
 - Clean up KVM's handling of "PMU MSRs to save", especially when vPMU
   support is disabled
 
 - Add PEBS support for Intel Sapphire Rapids
 
 - Fix a mostly benign overflow bug in SEV's send|receive_update_data()
 
 - Move several SVM-specific flags into vcpu_svm
 
 x86 Intel:
 
 - Handle NMI VM-Exits before leaving the noinstr region
 
 - A few trivial cleanups in the VM-Enter flows
 
 - Stop enabling VMFUNC for L1 purely to document that KVM doesn't support
   EPTP switching (or any other VM function) for L1
 
 - Fix a crash when using eVMCS's enlighted MSR bitmaps
 
 Generic:
 
 - Clean up the hardware enable and initialization flow, which was
   scattered around multiple arch-specific hooks.  Instead, just
   let the arch code call into generic code.  Both x86 and ARM should
   benefit from not having to fight common KVM code's notion of how
   to do initialization.
 
 - Account allocations in generic kvm_arch_alloc_vm()
 
 - Fix a memory leak if coalesced MMIO unregistration fails
 
 selftests:
 
 - On x86, cache the CPU vendor (AMD vs. Intel) and use the info to emit
   the correct hypercall instruction instead of relying on KVM to patch
   in VMMCALL
 
 - Use TAP interface for kvm_binary_stats_test and tsc_msrs_test
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm updates from Paolo Bonzini:
 "ARM:

   - Provide a virtual cache topology to the guest to avoid
     inconsistencies with migration on heterogenous systems. Non secure
     software has no practical need to traverse the caches by set/way in
     the first place

   - Add support for taking stage-2 access faults in parallel. This was
     an accidental omission in the original parallel faults
     implementation, but should provide a marginal improvement to
     machines w/o FEAT_HAFDBS (such as hardware from the fruit company)

   - A preamble to adding support for nested virtualization to KVM,
     including vEL2 register state, rudimentary nested exception
     handling and masking unsupported features for nested guests

   - Fixes to the PSCI relay that avoid an unexpected host SVE trap when
     resuming a CPU when running pKVM

   - VGIC maintenance interrupt support for the AIC

   - Improvements to the arch timer emulation, primarily aimed at
     reducing the trap overhead of running nested

   - Add CONFIG_USERFAULTFD to the KVM selftests config fragment in the
     interest of CI systems

   - Avoid VM-wide stop-the-world operations when a vCPU accesses its
     own redistributor

   - Serialize when toggling CPACR_EL1.SMEN to avoid unexpected
     exceptions in the host

   - Aesthetic and comment/kerneldoc fixes

   - Drop the vestiges of the old Columbia mailing list and add [Oliver]
     as co-maintainer

  RISC-V:

   - Fix wrong usage of PGDIR_SIZE instead of PUD_SIZE

   - Correctly place the guest in S-mode after redirecting a trap to the
     guest

   - Redirect illegal instruction traps to guest

   - SBI PMU support for guest

  s390:

   - Sort out confusion between virtual and physical addresses, which
     currently are the same on s390

   - A new ioctl that performs cmpxchg on guest memory

   - A few fixes

  x86:

   - Change tdp_mmu to a read-only parameter

   - Separate TDP and shadow MMU page fault paths

   - Enable Hyper-V invariant TSC control

   - Fix a variety of APICv and AVIC bugs, some of them real-world, some
     of them affecting architecurally legal but unlikely to happen in
     practice

   - Mark APIC timer as expired if its in one-shot mode and the count
     underflows while the vCPU task was being migrated

   - Advertise support for Intel's new fast REP string features

   - Fix a double-shootdown issue in the emergency reboot code

   - Ensure GIF=1 and disable SVM during an emergency reboot, i.e. give
     SVM similar treatment to VMX

   - Update Xen's TSC info CPUID sub-leaves as appropriate

   - Add support for Hyper-V's extended hypercalls, where "support" at
     this point is just forwarding the hypercalls to userspace

   - Clean up the kvm->lock vs. kvm->srcu sequences when updating the
     PMU and MSR filters

   - One-off fixes and cleanups

   - Fix and cleanup the range-based TLB flushing code, used when KVM is
     running on Hyper-V

   - Add support for filtering PMU events using a mask. If userspace
     wants to restrict heavily what events the guest can use, it can now
     do so without needing an absurd number of filter entries

   - Clean up KVM's handling of "PMU MSRs to save", especially when vPMU
     support is disabled

   - Add PEBS support for Intel Sapphire Rapids

   - Fix a mostly benign overflow bug in SEV's
     send|receive_update_data()

   - Move several SVM-specific flags into vcpu_svm

  x86 Intel:

   - Handle NMI VM-Exits before leaving the noinstr region

   - A few trivial cleanups in the VM-Enter flows

   - Stop enabling VMFUNC for L1 purely to document that KVM doesn't
     support EPTP switching (or any other VM function) for L1

   - Fix a crash when using eVMCS's enlighted MSR bitmaps

  Generic:

   - Clean up the hardware enable and initialization flow, which was
     scattered around multiple arch-specific hooks. Instead, just let
     the arch code call into generic code. Both x86 and ARM should
     benefit from not having to fight common KVM code's notion of how to
     do initialization

   - Account allocations in generic kvm_arch_alloc_vm()

   - Fix a memory leak if coalesced MMIO unregistration fails

  selftests:

   - On x86, cache the CPU vendor (AMD vs. Intel) and use the info to
     emit the correct hypercall instruction instead of relying on KVM to
     patch in VMMCALL

   - Use TAP interface for kvm_binary_stats_test and tsc_msrs_test"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (325 commits)
  KVM: SVM: hyper-v: placate modpost section mismatch error
  KVM: x86/mmu: Make tdp_mmu_allowed static
  KVM: arm64: nv: Use reg_to_encoding() to get sysreg ID
  KVM: arm64: nv: Only toggle cache for virtual EL2 when SCTLR_EL2 changes
  KVM: arm64: nv: Filter out unsupported features from ID regs
  KVM: arm64: nv: Emulate EL12 register accesses from the virtual EL2
  KVM: arm64: nv: Allow a sysreg to be hidden from userspace only
  KVM: arm64: nv: Emulate PSTATE.M for a guest hypervisor
  KVM: arm64: nv: Add accessors for SPSR_EL1, ELR_EL1 and VBAR_EL1 from virtual EL2
  KVM: arm64: nv: Handle SMCs taken from virtual EL2
  KVM: arm64: nv: Handle trapped ERET from virtual EL2
  KVM: arm64: nv: Inject HVC exceptions to the virtual EL2
  KVM: arm64: nv: Support virtual EL2 exceptions
  KVM: arm64: nv: Handle HCR_EL2.NV system register traps
  KVM: arm64: nv: Add nested virt VCPU primitives for vEL2 VCPU state
  KVM: arm64: nv: Add EL2 system registers to vcpu context
  KVM: arm64: nv: Allow userspace to set PSR_MODE_EL2x
  KVM: arm64: nv: Reset VCPU to EL2 registers if VCPU nested virt is set
  KVM: arm64: nv: Introduce nested virtualization VCPU feature
  KVM: arm64: Use the S2 MMU context to iterate over S2 table
  ...
2023-02-25 11:30:21 -08:00
Linus Torvalds 70756b49be It has been a moderately calm cycle for documentation; the significant
changes include:
 
 - Some significant additions to the memory-management documentation
 
 - Some improvements to navigation in the HTML-rendered docs
 
 - More Spanish and Chinese translations
 
 ...and the usual set of typo fixes and such.
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Merge tag 'docs-6.3' of git://git.lwn.net/linux

Pull documentation updates from Jonathan Corbet:
 "It has been a moderately calm cycle for documentation; the significant
  changes include:

   - Some significant additions to the memory-management documentation

   - Some improvements to navigation in the HTML-rendered docs

   - More Spanish and Chinese translations

  ... and the usual set of typo fixes and such"

* tag 'docs-6.3' of git://git.lwn.net/linux: (68 commits)
  Documentation/watchdog/hpwdt: Fix Format
  Documentation/watchdog/hpwdt: Fix Reference
  Documentation: core-api: padata: correct spelling
  docs/mm: Physical Memory: correct spelling in reference to CONFIG_PAGE_EXTENSION
  docs: Use HTML comments for the kernel-toc SPDX line
  docs: Add more information to the HTML sidebar
  Documentation: KVM: Update AMD memory encryption link
  printk: Document that CONFIG_BOOT_PRINTK_DELAY required for boot_delay=
  Documentation: userspace-api: correct spelling
  Documentation: sparc: correct spelling
  Documentation: driver-api: correct spelling
  Documentation: admin-guide: correct spelling
  docs: add workload-tracing document to admin-guide
  docs/admin-guide/mm: remove useless markup
  docs/mm: remove useless markup
  docs/mm: Physical Memory: remove useless markup
  docs/sp_SP: Add process magic-number translation
  docs: ftrace: always use canonical ftrace path
  Doc/damon: fix the data path error
  dma-buf: Add "dma-buf" to title of documentation
  ...
2023-02-22 12:00:20 -08:00
Paolo Bonzini e4922088f8 * Two more V!=R patches
* The last part of the cmpxchg patches
 * A few fixes
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Merge tag 'kvm-s390-next-6.3-1' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

* Two more V!=R patches
* The last part of the cmpxchg patches
* A few fixes
2023-02-15 12:35:26 -05:00
Paolo Bonzini 33436335e9 KVM/riscv changes for 6.3
- Fix wrong usage of PGDIR_SIZE to check page sizes
 - Fix privilege mode setting in kvm_riscv_vcpu_trap_redirect()
 - Redirect illegal instruction traps to guest
 - SBI PMU support for guest
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Merge tag 'kvm-riscv-6.3-1' of https://github.com/kvm-riscv/linux into HEAD

KVM/riscv changes for 6.3

- Fix wrong usage of PGDIR_SIZE to check page sizes
- Fix privilege mode setting in kvm_riscv_vcpu_trap_redirect()
- Redirect illegal instruction traps to guest
- SBI PMU support for guest
2023-02-15 12:33:28 -05:00
Janis Schoetterl-Glausch a7b0417328 Documentation: KVM: s390: Describe KVM_S390_MEMOP_F_CMPXCHG
Describe the semantics of the new KVM_S390_MEMOP_F_CMPXCHG flag for
absolute vm write memops which allows user space to perform (storage key
checked) cmpxchg operations on guest memory.

Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Link: https://lore.kernel.org/r/20230206164602.138068-14-scgl@linux.ibm.com
Message-Id: <20230206164602.138068-14-scgl@linux.ibm.com>
[frankja@de.ibm.com: Removed a line from an earlier version]
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
2023-02-07 18:06:00 +01:00
Nico Boehr f2d3155e2a KVM: s390: disable migration mode when dirty tracking is disabled
Migration mode is a VM attribute which enables tracking of changes in
storage attributes (PGSTE). It assumes dirty tracking is enabled on all
memslots to keep a dirty bitmap of pages with changed storage attributes.

When enabling migration mode, we currently check that dirty tracking is
enabled for all memslots. However, userspace can disable dirty tracking
without disabling migration mode.

Since migration mode is pointless with dirty tracking disabled, disable
migration mode whenever userspace disables dirty tracking on any slot.

Also update the documentation to clarify that dirty tracking must be
enabled when enabling migration mode, which is already enforced by the
code in kvm_s390_vm_start_migration().

Also highlight in the documentation for KVM_S390_GET_CMMA_BITS that it
can now fail with -EINVAL when dirty tracking is disabled while
migration mode is on. Move all the error codes to a table so this stays
readable.

To disable migration mode, slots_lock should be held, which is taken
in kvm_set_memory_region() and thus held in
kvm_arch_prepare_memory_region().

Restructure the prepare code a bit so all the sanity checking is done
before disabling migration mode. This ensures migration mode isn't
disabled when some sanity check fails.

Cc: stable@vger.kernel.org
Fixes: 190df4a212 ("KVM: s390: CMMA tracking, ESSA emulation, migration mode")
Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Link: https://lore.kernel.org/r/20230127140532.230651-2-nrb@linux.ibm.com
Message-Id: <20230127140532.230651-2-nrb@linux.ibm.com>
[frankja@linux.ibm.com: fixed commit message typo, moved api.rst error table upwards]
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
2023-02-07 18:05:59 +01:00
Paolo Bonzini 25b72cf7da KVM/arm64 fixes for 6.2, take #3
- Yet another fix for non-CPU accesses to the memory backing
   the VGICv3 subsystem
 
 - A set of fixes for the setlftest checking for the S1PTW
   behaviour after the fix that went in ealier in the cycle
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Merge tag 'kvmarm-fixes-6.2-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 fixes for 6.2, take #3

- Yet another fix for non-CPU accesses to the memory backing
  the VGICv3 subsystem

- A set of fixes for the setlftest checking for the S1PTW
  behaviour after the fix that went in ealier in the cycle
2023-02-04 08:57:43 -05:00
Wyes Karny fbabc2eaef Documentation: KVM: Update AMD memory encryption link
Update AMD memory encryption white-paper document link.
Previous link is not available. Update new available link.

Signed-off-by: Wyes Karny <wyes.karny@amd.com>
Reviewed-by: Carlos Bilbao <carlos.bilbao@amd.com>
Link: https://lore.kernel.org/r/20230125175948.21100-1-wyes.karny@amd.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2023-02-02 11:32:57 -07:00
Gavin Shan 6028acbe3a KVM: arm64: Allow no running vcpu on saving vgic3 pending table
We don't have a running VCPU context to save vgic3 pending table due
to KVM_DEV_ARM_VGIC_{GRP_CTRL, SAVE_PENDING_TABLES} command on KVM
device "kvm-arm-vgic-v3". The unknown case is caught by kvm-unit-tests.

   # ./kvm-unit-tests/tests/its-pending-migration
   WARNING: CPU: 120 PID: 7973 at arch/arm64/kvm/../../../virt/kvm/kvm_main.c:3325 \
   mark_page_dirty_in_slot+0x60/0xe0
    :
   mark_page_dirty_in_slot+0x60/0xe0
   __kvm_write_guest_page+0xcc/0x100
   kvm_write_guest+0x7c/0xb0
   vgic_v3_save_pending_tables+0x148/0x2a0
   vgic_set_common_attr+0x158/0x240
   vgic_v3_set_attr+0x4c/0x5c
   kvm_device_ioctl+0x100/0x160
   __arm64_sys_ioctl+0xa8/0xf0
   invoke_syscall.constprop.0+0x7c/0xd0
   el0_svc_common.constprop.0+0x144/0x160
   do_el0_svc+0x34/0x60
   el0_svc+0x3c/0x1a0
   el0t_64_sync_handler+0xb4/0x130
   el0t_64_sync+0x178/0x17c

Use vgic_write_guest_lock() to save vgic3 pending table.

Reported-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230126235451.469087-5-gshan@redhat.com
2023-01-29 18:46:11 +00:00
Gavin Shan 2f8b1ad222 KVM: arm64: Allow no running vcpu on restoring vgic3 LPI pending status
We don't have a running VCPU context to restore vgic3 LPI pending status
due to command KVM_DEV_ARM_{VGIC_GRP_CTRL, ITS_RESTORE_TABLES} on KVM
device "kvm-arm-vgic-its".

Use vgic_write_guest_lock() to restore vgic3 LPI pending status.

Signed-off-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230126235451.469087-4-gshan@redhat.com
2023-01-29 18:46:11 +00:00
Wang Yong 608348285a Documentation: KVM: fix typos in running-nested-guests.rst
change "gues" to "guest" and remove redundant ")".

Signed-off-by: Wang Yong <yongw.kernel@gmail.com>
Reviewed-by: Kashyap Chamarthy <kchamart@redhat.com>
Link: https://lore.kernel.org/r/20230110150046.549755-1-yongw.kernel@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2023-01-26 11:23:32 -07:00
SeongJae Park 941c95fdd6 Docs/subsystem-apis: Remove '[The ]Linux' prefixes from titles of listed documents
Some documents that listed on subsystem-apis have 'Linux' or 'The Linux'
title prefixes.  It's duplicated information, and makes finding the
document of interest with human eyes not easy.  Remove the prefixes from
the titles.

Signed-off-by: SeongJae Park <sj@kernel.org>
Acked-by: Iwona Winiarska <iwona.winiarska@intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20230122184834.181977-1-sj@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2023-01-24 15:27:08 -07:00
Aaron Lewis 14329b825f KVM: x86/pmu: Introduce masked events to the pmu event filter
When building a list of filter events, it can sometimes be a challenge
to fit all the events needed to adequately restrict the guest into the
limited space available in the pmu event filter.  This stems from the
fact that the pmu event filter requires each event (i.e. event select +
unit mask) be listed, when the intention might be to restrict the
event select all together, regardless of it's unit mask.  Instead of
increasing the number of filter events in the pmu event filter, add a
new encoding that is able to do a more generalized match on the unit mask.

Introduce masked events as another encoding the pmu event filter
understands.  Masked events has the fields: mask, match, and exclude.
When filtering based on these events, the mask is applied to the guest's
unit mask to see if it matches the match value (i.e. umask & mask ==
match).  The exclude bit can then be used to exclude events from that
match.  E.g. for a given event select, if it's easier to say which unit
mask values shouldn't be filtered, a masked event can be set up to match
all possible unit mask values, then another masked event can be set up to
match the unit mask values that shouldn't be filtered.

Userspace can query to see if this feature exists by looking for the
capability, KVM_CAP_PMU_EVENT_MASKED_EVENTS.

This feature is enabled by setting the flags field in the pmu event
filter to KVM_PMU_EVENT_FLAG_MASKED_EVENTS.

Events can be encoded by using KVM_PMU_ENCODE_MASKED_ENTRY().

It is an error to have a bit set outside the valid bits for a masked
event, and calls to KVM_SET_PMU_EVENT_FILTER will return -EINVAL in
such cases, including the high bits of the event select (35:32) if
called on Intel.

With these updates the filter matching code has been updated to match on
a common event.  Masked events were flexible enough to handle both event
types, so they were used as the common event.  This changes how guest
events get filtered because regardless of the type of event used in the
uAPI, they will be converted to masked events.  Because of this there
could be a slight performance hit because instead of matching the filter
event with a lookup on event select + unit mask, it does a lookup on event
select then walks the unit masks to find the match.  This shouldn't be a
big problem because I would expect the set of common event selects to be
small, and if they aren't the set can likely be reduced by using masked
events to generalize the unit mask.  Using one type of event when
filtering guest events allows for a common code path to be used.

Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Link: https://lore.kernel.org/r/20221220161236.555143-5-aaronlewis@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-01-24 10:06:12 -08:00
Paolo Bonzini f15a87c006 Merge branch 'kvm-lapic-fix-and-cleanup' into HEAD
The first half or so patches fix semi-urgent, real-world relevant APICv
and AVIC bugs.

The second half fixes a variety of AVIC and optimized APIC map bugs
where KVM doesn't play nice with various edge cases that are
architecturally legal(ish), but are unlikely to occur in most real world
scenarios

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-01-24 06:08:01 -05:00
Paolo Bonzini dc7c31e922 Merge branch 'kvm-v6.2-rc4-fixes' into HEAD
ARM:

* Fix the PMCR_EL0 reset value after the PMU rework

* Correctly handle S2 fault triggered by a S1 page table walk
  by not always classifying it as a write, as this breaks on
  R/O memslots

* Document why we cannot exit with KVM_EXIT_MMIO when taking
  a write fault from a S1 PTW on a R/O memslot

* Put the Apple M2 on the naughty list for not being able to
  correctly implement the vgic SEIS feature, just like the M1
  before it

* Reviewer updates: Alex is stepping down, replaced by Zenghui

x86:

* Fix various rare locking issues in Xen emulation and teach lockdep
  to detect them

* Documentation improvements

* Do not return host topology information from KVM_GET_SUPPORTED_CPUID
2023-01-24 06:05:23 -05:00
Sean Christopherson 5b84b02917 KVM: x86: Honor architectural behavior for aliased 8-bit APIC IDs
Apply KVM's hotplug hack if and only if userspace has enabled 32-bit IDs
for x2APIC.  If 32-bit IDs are not enabled, disable the optimized map to
honor x86 architectural behavior if multiple vCPUs shared a physical APIC
ID.  As called out in the changelog that added the hack, all CPUs whose
(possibly truncated) APIC ID matches the target are supposed to receive
the IPI.

  KVM intentionally differs from real hardware, because real hardware
  (Knights Landing) does just "x2apic_id & 0xff" to decide whether to
  accept the interrupt in xAPIC mode and it can deliver one interrupt to
  more than one physical destination, e.g. 0x123 to 0x123 and 0x23.

Applying the hack even when x2APIC is not fully enabled means KVM doesn't
correctly handle scenarios where the guest has aliased xAPIC IDs across
multiple vCPUs, as only the vCPU with the lowest vCPU ID will receive any
interrupts.  It's extremely unlikely any real world guest aliases APIC
IDs, or even modifies APIC IDs, but KVM's behavior is arbitrary, e.g. the
lowest vCPU ID "wins" regardless of which vCPU is "aliasing" and which
vCPU is "normal".

Furthermore, the hack is _not_ guaranteed to work!  The hack works if and
only if the optimized APIC map is successfully allocated.  If the map
allocation fails (unlikely), KVM will fall back to its unoptimized
behavior, which _does_ honor the architectural behavior.

Pivot on 32-bit x2APIC IDs being enabled as that is required to take
advantage of the hotplug hack (see kvm_apic_state_fixup()), i.e. won't
break existing setups unless they are way, way off in the weeds.

And an entry in KVM's errata to document the hack.  Alternatively, KVM
could provide an actual x2APIC quirk and document the hack that way, but
there's unlikely to ever be a use case for disabling the quirk.  Go the
errata route to avoid having to validate a quirk no one cares about.

Fixes: 5bd5db385b ("KVM: x86: allow hotplug of VCPU with APIC ID over 0xff")
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20230106011306.85230-23-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-01-13 10:45:30 -05:00
David Woodhouse 310bc39546 KVM: x86/xen: Avoid deadlock by adding kvm->arch.xen.xen_lock leaf node lock
In commit 14243b3871 ("KVM: x86/xen: Add KVM_IRQ_ROUTING_XEN_EVTCHN
and event channel delivery") the clever version of me left some helpful
notes for those who would come after him:

       /*
        * For the irqfd workqueue, using the main kvm->lock mutex is
        * fine since this function is invoked from kvm_set_irq() with
        * no other lock held, no srcu. In future if it will be called
        * directly from a vCPU thread (e.g. on hypercall for an IPI)
        * then it may need to switch to using a leaf-node mutex for
        * serializing the shared_info mapping.
        */
       mutex_lock(&kvm->lock);

In commit 2fd6df2f2b ("KVM: x86/xen: intercept EVTCHNOP_send from guests")
the other version of me ran straight past that comment without reading it,
and introduced a potential deadlock by taking vcpu->mutex and kvm->lock
in the wrong order.

Solve this as originally suggested, by adding a leaf-node lock in the Xen
state rather than using kvm->lock for it.

Fixes: 2fd6df2f2b ("KVM: x86/xen: intercept EVTCHNOP_send from guests")
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20230111180651.14394-4-dwmw2@infradead.org>
[Rebase, add docs. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-01-11 17:45:58 -05:00
Paolo Bonzini 71d0393576 KVM/arm64 fixes for 6.2, take #1
- Fix the PMCR_EL0 reset value after the PMU rework
 
 - Correctly handle S2 fault triggered by a S1 page table walk
   by not always classifying it as a write, as this breaks on
   R/O memslots
 
 - Document why we cannot exit with KVM_EXIT_MMIO when taking
   a write fault from a S1 PTW on a R/O memslot
 
 - Put the Apple M2 on the naughty step for not being able to
   correctly implement the vgic SEIS feature, just liek the M1
   before it
 
 - Reviewer updates: Alex is stepping down, replaced by Zenghui
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Merge tag 'kvmarm-fixes-6.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into kvm-master

KVM/arm64 fixes for 6.2, take #1

- Fix the PMCR_EL0 reset value after the PMU rework

- Correctly handle S2 fault triggered by a S1 page table walk
  by not always classifying it as a write, as this breaks on
  R/O memslots

- Document why we cannot exit with KVM_EXIT_MMIO when taking
  a write fault from a S1 PTW on a R/O memslot

- Put the Apple M2 on the naughty step for not being able to
  correctly implement the vgic SEIS feature, just liek the M1
  before it

- Reviewer updates: Alex is stepping down, replaced by Zenghui
2023-01-11 13:31:53 -05:00
Paolo Bonzini 3a9ae31ac2 Documentation: kvm: fix SRCU locking order docs
kvm->srcu is taken in KVM_RUN and several other vCPU ioctls, therefore
vcpu->mutex is susceptible to the same deadlock that is documented
for kvm->slots_lock.  The same holds for kvm->lock, since kvm->lock
is held outside vcpu->mutex.  Fix the documentation and rearrange it
to highlight the difference between these locks and kvm->slots_arch_lock,
and how kvm->slots_arch_lock can be useful while processing a vmexit.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-01-11 13:31:33 -05:00
Paolo Bonzini 45e966fcca KVM: x86: Do not return host topology information from KVM_GET_SUPPORTED_CPUID
Passing the host topology to the guest is almost certainly wrong
and will confuse the scheduler.  In addition, several fields of
these CPUID leaves vary on each processor; it is simply impossible to
return the right values from KVM_GET_SUPPORTED_CPUID in such a way that
they can be passed to KVM_SET_CPUID2.

The values that will most likely prevent confusion are all zeroes.
Userspace will have to override it anyway if it wishes to present a
specific topology to the guest.

Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-01-09 05:35:21 -05:00
Marc Zyngier afbb1b1cae Merge branch kvm-arm64/s1ptw-write-fault into kvmarm-master/fixes
* kvm-arm64/s1ptw-write-fault:
  : .
  : Fix S1PTW fault handling that was until then always taken
  : as a write. From the cover letter:
  :
  : `Recent developments on the EFI front have resulted in guests that
  : simply won't boot if the page tables are in a read-only memslot and
  : that you're a bit unlucky in the way S2 gets paged in... The core
  : issue is related to the fact that we treat a S1PTW as a write, which
  : is close enough to what needs to be done. Until to get to RO memslots.
  :
  : The first patch fixes this and is definitely a stable candidate. It
  : splits the faulting of page tables in two steps (RO translation fault,
  : followed by a writable permission fault -- should it even happen).
  : The second one documents the slightly odd behaviour of PTW writes to
  : RO memslot, which do not result in a KVM_MMIO exit. The last patch is
  : totally optional, only tangentially related, and randomly repainting
  : stuff (maybe that's contagious, who knows)."
  :
  : .
  KVM: arm64: Convert FSC_* over to ESR_ELx_FSC_*
  KVM: arm64: Document the behaviour of S1PTW faults on RO memslots
  KVM: arm64: Fix S1PTW handling on RO memslots

Signed-off-by: Marc Zyngier <maz@kernel.org>
2023-01-05 15:25:54 +00:00
Marc Zyngier b8f8d190fa KVM: arm64: Document the behaviour of S1PTW faults on RO memslots
Although the KVM API says that a write to a RO memslot must result
in a KVM_EXIT_MMIO describing the write, the arm64 architecture
doesn't provide the *data* written by a Stage-1 page table walk
(we only get the address).

Since there isn't much userspace can do with so little information
anyway, document the fact that such an access results in a guest
exception, not an exit. This is consistent with the guest being
terminally broken anyway.

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
2023-01-03 10:01:52 +00:00
Isaku Yamahata 0bf50497f0 KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock
Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock now
that KVM hooks CPU hotplug during the ONLINE phase, which can sleep.
Previously, KVM hooked the STARTING phase, which is not allowed to sleep
and thus could not take kvm_lock (a mutex).  This effectively allows the
task that's initiating hardware enabling/disabling to preempted and/or
migrated.

Note, the Documentation/virt/kvm/locking.rst statement that kvm_count_lock
is "raw" because hardware enabling/disabling needs to be atomic with
respect to migration is wrong on multiple fronts.  First, while regular
spinlocks can be preempted, the task holding the lock cannot be migrated.
Second, preventing migration is not required.  on_each_cpu() disables
preemption, which ensures that cpus_hardware_enabled correctly reflects
hardware state.  The task may be preempted/migrated between bumping
kvm_usage_count and invoking on_each_cpu(), but that's perfectly ok as
kvm_usage_count is still protected, e.g. other tasks that call
hardware_enable_all() will be blocked until the preempted/migrated owner
exits its critical section.

KVM does have lockless accesses to kvm_usage_count in the suspend/resume
flows, but those are safe because all tasks must be frozen prior to
suspending CPUs, and a task cannot be frozen while it holds one or more
locks (userspace tasks are frozen via a fake signal).

Preemption doesn't need to be explicitly disabled in the hotplug path.
The hotplug thread is pinned to the CPU that's being hotplugged, and KVM
only cares about having a stable CPU, i.e. to ensure hardware is enabled
on the correct CPU.  Lockep, i.e. check_preemption_disabled(), plays nice
with this state too, as is_percpu_thread() is true for the hotplug thread.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221130230934.1014142-45-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29 15:48:34 -05:00
Sean Christopherson 3af4a9e61e KVM: x86: Serialize vendor module initialization (hardware setup)
Acquire a new mutex, vendor_module_lock, in kvm_x86_vendor_init() while
doing hardware setup to ensure that concurrent calls are fully serialized.
KVM rejects attempts to load vendor modules if a different module has
already been loaded, but doesn't handle the case where multiple vendor
modules are loaded at the same time, and module_init() doesn't run under
the global module_mutex.

Note, in practice, this is likely a benign bug as no platform exists that
supports both SVM and VMX, i.e. barring a weird VM setup, one of the
vendor modules is guaranteed to fail a support check before modifying
common KVM state.

Alternatively, KVM could perform an atomic CMPXCHG on .hardware_enable,
but that comes with its own ugliness as it would require setting
.hardware_enable before success is guaranteed, e.g. attempting to load
the "wrong" could result in spurious failure to load the "right" module.

Introduce a new mutex as using kvm_lock is extremely deadlock prone due
to kvm_lock being taken under cpus_write_lock(), and in the future, under
under cpus_read_lock().  Any operation that takes cpus_read_lock() while
holding kvm_lock would potentially deadlock, e.g. kvm_timer_init() takes
cpus_read_lock() to register a callback.  In theory, KVM could avoid
such problematic paths, i.e. do less setup under kvm_lock, but avoiding
all calls to cpus_read_lock() is subtly difficult and thus fragile.  E.g.
updating static calls also acquires cpus_read_lock().

Inverting the lock ordering, i.e. always taking kvm_lock outside
cpus_read_lock(), is not a viable option as kvm_lock is taken in various
callbacks that may be invoked under cpus_read_lock(), e.g. x86's
kvmclock_cpufreq_notifier().

The lockdep splat below is dependent on future patches to take
cpus_read_lock() in hardware_enable_all(), but as above, deadlock is
already is already possible.

  ======================================================
  WARNING: possible circular locking dependency detected
  6.0.0-smp--7ec93244f194-init2 #27 Tainted: G           O
  ------------------------------------------------------
  stable/251833 is trying to acquire lock:
  ffffffffc097ea28 (kvm_lock){+.+.}-{3:3}, at: hardware_enable_all+0x1f/0xc0 [kvm]

               but task is already holding lock:
  ffffffffa2456828 (cpu_hotplug_lock){++++}-{0:0}, at: hardware_enable_all+0xf/0xc0 [kvm]

               which lock already depends on the new lock.

               the existing dependency chain (in reverse order) is:

               -> #1 (cpu_hotplug_lock){++++}-{0:0}:
         cpus_read_lock+0x2a/0xa0
         __cpuhp_setup_state+0x2b/0x60
         __kvm_x86_vendor_init+0x16a/0x1870 [kvm]
         kvm_x86_vendor_init+0x23/0x40 [kvm]
         0xffffffffc0a4d02b
         do_one_initcall+0x110/0x200
         do_init_module+0x4f/0x250
         load_module+0x1730/0x18f0
         __se_sys_finit_module+0xca/0x100
         __x64_sys_finit_module+0x1d/0x20
         do_syscall_64+0x3d/0x80
         entry_SYSCALL_64_after_hwframe+0x63/0xcd

               -> #0 (kvm_lock){+.+.}-{3:3}:
         __lock_acquire+0x16f4/0x30d0
         lock_acquire+0xb2/0x190
         __mutex_lock+0x98/0x6f0
         mutex_lock_nested+0x1b/0x20
         hardware_enable_all+0x1f/0xc0 [kvm]
         kvm_dev_ioctl+0x45e/0x930 [kvm]
         __se_sys_ioctl+0x77/0xc0
         __x64_sys_ioctl+0x1d/0x20
         do_syscall_64+0x3d/0x80
         entry_SYSCALL_64_after_hwframe+0x63/0xcd

               other info that might help us debug this:

   Possible unsafe locking scenario:

         CPU0                    CPU1
         ----                    ----
    lock(cpu_hotplug_lock);
                                 lock(kvm_lock);
                                 lock(cpu_hotplug_lock);
    lock(kvm_lock);

                *** DEADLOCK ***

  1 lock held by stable/251833:
   #0: ffffffffa2456828 (cpu_hotplug_lock){++++}-{0:0}, at: hardware_enable_all+0xf/0xc0 [kvm]

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221130230934.1014142-16-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29 15:41:03 -05:00
Paolo Bonzini fc471e8310 Merge branch 'kvm-late-6.1' into HEAD
x86:

* Change tdp_mmu to a read-only parameter

* Separate TDP and shadow MMU page fault paths

* Enable Hyper-V invariant TSC control

selftests:

* Use TAP interface for kvm_binary_stats_test and tsc_msrs_test

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29 15:36:47 -05:00
Paolo Bonzini a5496886eb Merge branch 'kvm-late-6.1-fixes' into HEAD
x86:

* several fixes to nested VMX execution controls

* fixes and clarification to the documentation for Xen emulation

* do not unnecessarily release a pmu event with zero period

* MMU fixes

* fix Coverity warning in kvm_hv_flush_tlb()

selftests:

* fixes for the ucall mechanism in selftests

* other fixes mostly related to compilation with clang
2022-12-28 07:19:14 -05:00
Paolo Bonzini 02d9a04da4 Documentation: kvm: clarify SRCU locking order
Currently only the locking order of SRCU vs kvm->slots_arch_lock
and kvm->slots_lock is documented.  Extend this to kvm->lock
since Xen emulation got it terribly wrong.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-28 06:02:54 -05:00
David Woodhouse af2808906a KVM: x86/xen: Documentation updates and clarifications
Most notably, the KVM_XEN_EVTCHN_RESET feature had escaped documentation
entirely. Along with how to turn most stuff off on SHUTDOWN_soft_reset.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20221226120320.1125390-6-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-27 06:01:50 -05:00
Sean Christopherson 23e528d9bc KVM: Delete extra block of "};" in the KVM API documentation
Delete an extra block of code/documentation that snuck in when KVM's
documentation was converted to ReST format.

Fixes: 106ee47dc6 ("docs: kvm: Convert api.txt to ReST format")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221207003637.2041211-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-27 06:00:51 -05:00
Linus Torvalds 8fa590bf34 ARM64:
* Enable the per-vcpu dirty-ring tracking mechanism, together with an
   option to keep the good old dirty log around for pages that are
   dirtied by something other than a vcpu.
 
 * Switch to the relaxed parallel fault handling, using RCU to delay
   page table reclaim and giving better performance under load.
 
 * Relax the MTE ABI, allowing a VMM to use the MAP_SHARED mapping option,
   which multi-process VMMs such as crosvm rely on (see merge commit 382b5b87a97d:
   "Fix a number of issues with MTE, such as races on the tags being
   initialised vs the PG_mte_tagged flag as well as the lack of support
   for VM_SHARED when KVM is involved.  Patches from Catalin Marinas and
   Peter Collingbourne").
 
 * Merge the pKVM shadow vcpu state tracking that allows the hypervisor
   to have its own view of a vcpu, keeping that state private.
 
 * Add support for the PMUv3p5 architecture revision, bringing support
   for 64bit counters on systems that support it, and fix the
   no-quite-compliant CHAIN-ed counter support for the machines that
   actually exist out there.
 
 * Fix a handful of minor issues around 52bit VA/PA support (64kB pages
   only) as a prefix of the oncoming support for 4kB and 16kB pages.
 
 * Pick a small set of documentation and spelling fixes, because no
   good merge window would be complete without those.
 
 s390:
 
 * Second batch of the lazy destroy patches
 
 * First batch of KVM changes for kernel virtual != physical address support
 
 * Removal of a unused function
 
 x86:
 
 * Allow compiling out SMM support
 
 * Cleanup and documentation of SMM state save area format
 
 * Preserve interrupt shadow in SMM state save area
 
 * Respond to generic signals during slow page faults
 
 * Fixes and optimizations for the non-executable huge page errata fix.
 
 * Reprogram all performance counters on PMU filter change
 
 * Cleanups to Hyper-V emulation and tests
 
 * Process Hyper-V TLB flushes from a nested guest (i.e. from a L2 guest
   running on top of a L1 Hyper-V hypervisor)
 
 * Advertise several new Intel features
 
 * x86 Xen-for-KVM:
 
 ** Allow the Xen runstate information to cross a page boundary
 
 ** Allow XEN_RUNSTATE_UPDATE flag behaviour to be configured
 
 ** Add support for 32-bit guests in SCHEDOP_poll
 
 * Notable x86 fixes and cleanups:
 
 ** One-off fixes for various emulation flows (SGX, VMXON, NRIPS=0).
 
 ** Reinstate IBPB on emulated VM-Exit that was incorrectly dropped a few
    years back when eliminating unnecessary barriers when switching between
    vmcs01 and vmcs02.
 
 ** Clean up vmread_error_trampoline() to make it more obvious that params
    must be passed on the stack, even for x86-64.
 
 ** Let userspace set all supported bits in MSR_IA32_FEAT_CTL irrespective
    of the current guest CPUID.
 
 ** Fudge around a race with TSC refinement that results in KVM incorrectly
    thinking a guest needs TSC scaling when running on a CPU with a
    constant TSC, but no hardware-enumerated TSC frequency.
 
 ** Advertise (on AMD) that the SMM_CTL MSR is not supported
 
 ** Remove unnecessary exports
 
 Generic:
 
 * Support for responding to signals during page faults; introduces
   new FOLL_INTERRUPTIBLE flag that was reviewed by mm folks
 
 Selftests:
 
 * Fix an inverted check in the access tracking perf test, and restore
   support for asserting that there aren't too many idle pages when
   running on bare metal.
 
 * Fix build errors that occur in certain setups (unsure exactly what is
   unique about the problematic setup) due to glibc overriding
   static_assert() to a variant that requires a custom message.
 
 * Introduce actual atomics for clear/set_bit() in selftests
 
 * Add support for pinning vCPUs in dirty_log_perf_test.
 
 * Rename the so called "perf_util" framework to "memstress".
 
 * Add a lightweight psuedo RNG for guest use, and use it to randomize
   the access pattern and write vs. read percentage in the memstress tests.
 
 * Add a common ucall implementation; code dedup and pre-work for running
   SEV (and beyond) guests in selftests.
 
 * Provide a common constructor and arch hook, which will eventually be
   used by x86 to automatically select the right hypercall (AMD vs. Intel).
 
 * A bunch of added/enabled/fixed selftests for ARM64, covering memslots,
   breakpoints, stage-2 faults and access tracking.
 
 * x86-specific selftest changes:
 
 ** Clean up x86's page table management.
 
 ** Clean up and enhance the "smaller maxphyaddr" test, and add a related
    test to cover generic emulation failure.
 
 ** Clean up the nEPT support checks.
 
 ** Add X86_PROPERTY_* framework to retrieve multi-bit CPUID values.
 
 ** Fix an ordering issue in the AMX test introduced by recent conversions
    to use kvm_cpu_has(), and harden the code to guard against similar bugs
    in the future.  Anything that tiggers caching of KVM's supported CPUID,
    kvm_cpu_has() in this case, effectively hides opt-in XSAVE features if
    the caching occurs before the test opts in via prctl().
 
 Documentation:
 
 * Remove deleted ioctls from documentation
 
 * Clean up the docs for the x86 MSR filter.
 
 * Various fixes
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm updates from Paolo Bonzini:
 "ARM64:

   - Enable the per-vcpu dirty-ring tracking mechanism, together with an
     option to keep the good old dirty log around for pages that are
     dirtied by something other than a vcpu.

   - Switch to the relaxed parallel fault handling, using RCU to delay
     page table reclaim and giving better performance under load.

   - Relax the MTE ABI, allowing a VMM to use the MAP_SHARED mapping
     option, which multi-process VMMs such as crosvm rely on (see merge
     commit 382b5b87a97d: "Fix a number of issues with MTE, such as
     races on the tags being initialised vs the PG_mte_tagged flag as
     well as the lack of support for VM_SHARED when KVM is involved.
     Patches from Catalin Marinas and Peter Collingbourne").

   - Merge the pKVM shadow vcpu state tracking that allows the
     hypervisor to have its own view of a vcpu, keeping that state
     private.

   - Add support for the PMUv3p5 architecture revision, bringing support
     for 64bit counters on systems that support it, and fix the
     no-quite-compliant CHAIN-ed counter support for the machines that
     actually exist out there.

   - Fix a handful of minor issues around 52bit VA/PA support (64kB
     pages only) as a prefix of the oncoming support for 4kB and 16kB
     pages.

   - Pick a small set of documentation and spelling fixes, because no
     good merge window would be complete without those.

  s390:

   - Second batch of the lazy destroy patches

   - First batch of KVM changes for kernel virtual != physical address
     support

   - Removal of a unused function

  x86:

   - Allow compiling out SMM support

   - Cleanup and documentation of SMM state save area format

   - Preserve interrupt shadow in SMM state save area

   - Respond to generic signals during slow page faults

   - Fixes and optimizations for the non-executable huge page errata
     fix.

   - Reprogram all performance counters on PMU filter change

   - Cleanups to Hyper-V emulation and tests

   - Process Hyper-V TLB flushes from a nested guest (i.e. from a L2
     guest running on top of a L1 Hyper-V hypervisor)

   - Advertise several new Intel features

   - x86 Xen-for-KVM:

      - Allow the Xen runstate information to cross a page boundary

      - Allow XEN_RUNSTATE_UPDATE flag behaviour to be configured

      - Add support for 32-bit guests in SCHEDOP_poll

   - Notable x86 fixes and cleanups:

      - One-off fixes for various emulation flows (SGX, VMXON, NRIPS=0).

      - Reinstate IBPB on emulated VM-Exit that was incorrectly dropped
        a few years back when eliminating unnecessary barriers when
        switching between vmcs01 and vmcs02.

      - Clean up vmread_error_trampoline() to make it more obvious that
        params must be passed on the stack, even for x86-64.

      - Let userspace set all supported bits in MSR_IA32_FEAT_CTL
        irrespective of the current guest CPUID.

      - Fudge around a race with TSC refinement that results in KVM
        incorrectly thinking a guest needs TSC scaling when running on a
        CPU with a constant TSC, but no hardware-enumerated TSC
        frequency.

      - Advertise (on AMD) that the SMM_CTL MSR is not supported

      - Remove unnecessary exports

  Generic:

   - Support for responding to signals during page faults; introduces
     new FOLL_INTERRUPTIBLE flag that was reviewed by mm folks

  Selftests:

   - Fix an inverted check in the access tracking perf test, and restore
     support for asserting that there aren't too many idle pages when
     running on bare metal.

   - Fix build errors that occur in certain setups (unsure exactly what
     is unique about the problematic setup) due to glibc overriding
     static_assert() to a variant that requires a custom message.

   - Introduce actual atomics for clear/set_bit() in selftests

   - Add support for pinning vCPUs in dirty_log_perf_test.

   - Rename the so called "perf_util" framework to "memstress".

   - Add a lightweight psuedo RNG for guest use, and use it to randomize
     the access pattern and write vs. read percentage in the memstress
     tests.

   - Add a common ucall implementation; code dedup and pre-work for
     running SEV (and beyond) guests in selftests.

   - Provide a common constructor and arch hook, which will eventually
     be used by x86 to automatically select the right hypercall (AMD vs.
     Intel).

   - A bunch of added/enabled/fixed selftests for ARM64, covering
     memslots, breakpoints, stage-2 faults and access tracking.

   - x86-specific selftest changes:

      - Clean up x86's page table management.

      - Clean up and enhance the "smaller maxphyaddr" test, and add a
        related test to cover generic emulation failure.

      - Clean up the nEPT support checks.

      - Add X86_PROPERTY_* framework to retrieve multi-bit CPUID values.

      - Fix an ordering issue in the AMX test introduced by recent
        conversions to use kvm_cpu_has(), and harden the code to guard
        against similar bugs in the future. Anything that tiggers
        caching of KVM's supported CPUID, kvm_cpu_has() in this case,
        effectively hides opt-in XSAVE features if the caching occurs
        before the test opts in via prctl().

  Documentation:

   - Remove deleted ioctls from documentation

   - Clean up the docs for the x86 MSR filter.

   - Various fixes"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (361 commits)
  KVM: x86: Add proper ReST tables for userspace MSR exits/flags
  KVM: selftests: Allocate ucall pool from MEM_REGION_DATA
  KVM: arm64: selftests: Align VA space allocator with TTBR0
  KVM: arm64: Fix benign bug with incorrect use of VA_BITS
  KVM: arm64: PMU: Fix period computation for 64bit counters with 32bit overflow
  KVM: x86: Advertise that the SMM_CTL MSR is not supported
  KVM: x86: remove unnecessary exports
  KVM: selftests: Fix spelling mistake "probabalistic" -> "probabilistic"
  tools: KVM: selftests: Convert clear/set_bit() to actual atomics
  tools: Drop "atomic_" prefix from atomic test_and_set_bit()
  tools: Drop conflicting non-atomic test_and_{clear,set}_bit() helpers
  KVM: selftests: Use non-atomic clear/set bit helpers in KVM tests
  perf tools: Use dedicated non-atomic clear/set bit helpers
  tools: Take @bit as an "unsigned long" in {clear,set}_bit() helpers
  KVM: arm64: selftests: Enable single-step without a "full" ucall()
  KVM: x86: fix APICv/x2AVIC disabled when vm reboot by itself
  KVM: Remove stale comment about KVM_REQ_UNHALT
  KVM: Add missing arch for KVM_CREATE_DEVICE and KVM_{SET,GET}_DEVICE_ATTR
  KVM: Reference to kvm_userspace_memory_region in doc and comments
  KVM: Delete all references to removed KVM_SET_MEMORY_ALIAS ioctl
  ...
2022-12-15 11:12:21 -08:00
Sean Christopherson 549a715b98 KVM: x86: Add proper ReST tables for userspace MSR exits/flags
Add ReST formatting to the set of userspace MSR exits/flags so that the
resulting HTML docs generate a table instead of malformed gunk.  This
also fixes a warning that was introduced by a recent cleanup of the
relevant documentation (yay copy+paste).

 >> Documentation/virt/kvm/api.rst:7287: WARNING: Block quote ends
    without a blank line; unexpected unindent.

Fixes: 1ae099540e ("KVM: x86: Allow deflecting unknown MSR accesses to user space")
Fixes: 1f15814718 ("KVM: x86: Clean up KVM_CAP_X86_USER_SPACE_MSR documentation")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221207000959.2035098-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-14 13:28:31 -05:00
Linus Torvalds a89ef2aa55 Add TDX guest attestation infrastructure and driver
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Merge tag 'x86_tdx_for_6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 tdx updates from Dave Hansen:
 "This includes a single chunk of new functionality for TDX guests which
  allows them to talk to the trusted TDX module software and obtain an
  attestation report.

  This report can then be used to prove the trustworthiness of the guest
  to a third party and get access to things like storage encryption
  keys"

* tag 'x86_tdx_for_6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  selftests/tdx: Test TDX attestation GetReport support
  virt: Add TDX guest driver
  x86/tdx: Add a wrapper to get TDREPORT0 from the TDX Module
2022-12-12 14:27:49 -08:00
Paolo Bonzini 9352e7470a Merge remote-tracking branch 'kvm/queue' into HEAD
x86 Xen-for-KVM:

* Allow the Xen runstate information to cross a page boundary

* Allow XEN_RUNSTATE_UPDATE flag behaviour to be configured

* add support for 32-bit guests in SCHEDOP_poll

x86 fixes:

* One-off fixes for various emulation flows (SGX, VMXON, NRIPS=0).

* Reinstate IBPB on emulated VM-Exit that was incorrectly dropped a few
   years back when eliminating unnecessary barriers when switching between
   vmcs01 and vmcs02.

* Clean up the MSR filter docs.

* Clean up vmread_error_trampoline() to make it more obvious that params
  must be passed on the stack, even for x86-64.

* Let userspace set all supported bits in MSR_IA32_FEAT_CTL irrespective
  of the current guest CPUID.

* Fudge around a race with TSC refinement that results in KVM incorrectly
  thinking a guest needs TSC scaling when running on a CPU with a
  constant TSC, but no hardware-enumerated TSC frequency.

* Advertise (on AMD) that the SMM_CTL MSR is not supported

* Remove unnecessary exports

Selftests:

* Fix an inverted check in the access tracking perf test, and restore
  support for asserting that there aren't too many idle pages when
  running on bare metal.

* Fix an ordering issue in the AMX test introduced by recent conversions
  to use kvm_cpu_has(), and harden the code to guard against similar bugs
  in the future.  Anything that tiggers caching of KVM's supported CPUID,
  kvm_cpu_has() in this case, effectively hides opt-in XSAVE features if
  the caching occurs before the test opts in via prctl().

* Fix build errors that occur in certain setups (unsure exactly what is
  unique about the problematic setup) due to glibc overriding
  static_assert() to a variant that requires a custom message.

* Introduce actual atomics for clear/set_bit() in selftests

Documentation:

* Remove deleted ioctls from documentation

* Various fixes
2022-12-12 15:54:07 -05:00
Paolo Bonzini eb5618911a KVM/arm64 updates for 6.2
- Enable the per-vcpu dirty-ring tracking mechanism, together with an
   option to keep the good old dirty log around for pages that are
   dirtied by something other than a vcpu.
 
 - Switch to the relaxed parallel fault handling, using RCU to delay
   page table reclaim and giving better performance under load.
 
 - Relax the MTE ABI, allowing a VMM to use the MAP_SHARED mapping
   option, which multi-process VMMs such as crosvm rely on.
 
 - Merge the pKVM shadow vcpu state tracking that allows the hypervisor
   to have its own view of a vcpu, keeping that state private.
 
 - Add support for the PMUv3p5 architecture revision, bringing support
   for 64bit counters on systems that support it, and fix the
   no-quite-compliant CHAIN-ed counter support for the machines that
   actually exist out there.
 
 - Fix a handful of minor issues around 52bit VA/PA support (64kB pages
   only) as a prefix of the oncoming support for 4kB and 16kB pages.
 
 - Add/Enable/Fix a bunch of selftests covering memslots, breakpoints,
   stage-2 faults and access tracking. You name it, we got it, we
   probably broke it.
 
 - Pick a small set of documentation and spelling fixes, because no
   good merge window would be complete without those.
 
 As a side effect, this tag also drags:
 
 - The 'kvmarm-fixes-6.1-3' tag as a dependency to the dirty-ring
   series
 
 - A shared branch with the arm64 tree that repaints all the system
   registers to match the ARM ARM's naming, and resulting in
   interesting conflicts
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Merge tag 'kvmarm-6.2' of https://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 updates for 6.2

- Enable the per-vcpu dirty-ring tracking mechanism, together with an
  option to keep the good old dirty log around for pages that are
  dirtied by something other than a vcpu.

- Switch to the relaxed parallel fault handling, using RCU to delay
  page table reclaim and giving better performance under load.

- Relax the MTE ABI, allowing a VMM to use the MAP_SHARED mapping
  option, which multi-process VMMs such as crosvm rely on.

- Merge the pKVM shadow vcpu state tracking that allows the hypervisor
  to have its own view of a vcpu, keeping that state private.

- Add support for the PMUv3p5 architecture revision, bringing support
  for 64bit counters on systems that support it, and fix the
  no-quite-compliant CHAIN-ed counter support for the machines that
  actually exist out there.

- Fix a handful of minor issues around 52bit VA/PA support (64kB pages
  only) as a prefix of the oncoming support for 4kB and 16kB pages.

- Add/Enable/Fix a bunch of selftests covering memslots, breakpoints,
  stage-2 faults and access tracking. You name it, we got it, we
  probably broke it.

- Pick a small set of documentation and spelling fixes, because no
  good merge window would be complete without those.

As a side effect, this tag also drags:

- The 'kvmarm-fixes-6.1-3' tag as a dependency to the dirty-ring
  series

- A shared branch with the arm64 tree that repaints all the system
  registers to match the ARM ARM's naming, and resulting in
  interesting conflicts
2022-12-09 09:12:12 +01:00
Marc Zyngier 86f27d849b Merge branch kvm-arm64/misc-6.2 into kvmarm-master/next
* kvm-arm64/misc-6.2:
  : .
  : Misc fixes for 6.2:
  :
  : - Fix formatting for the pvtime documentation
  :
  : - Fix a comment in the VHE-specific Makefile
  : .
  KVM: arm64: Fix typo in comment
  KVM: arm64: Fix pvtime documentation

Signed-off-by: Marc Zyngier <maz@kernel.org>
2022-12-05 14:39:12 +00:00
Marc Zyngier 382b5b87a9 Merge branch kvm-arm64/mte-map-shared into kvmarm-master/next
* kvm-arm64/mte-map-shared:
  : .
  : Update the MTE support to allow the VMM to use shared mappings
  : to back the memslots exposed to MTE-enabled guests.
  :
  : Patches courtesy of Catalin Marinas and Peter Collingbourne.
  : .
  : Fix a number of issues with MTE, such as races on the tags
  : being initialised vs the PG_mte_tagged flag as well as the
  : lack of support for VM_SHARED when KVM is involved.
  :
  : Patches from Catalin Marinas and Peter Collingbourne.
  : .
  Documentation: document the ABI changes for KVM_CAP_ARM_MTE
  KVM: arm64: permit all VM_MTE_ALLOWED mappings with MTE enabled
  KVM: arm64: unify the tests for VMAs in memslots when MTE is enabled
  arm64: mte: Lock a page for MTE tag initialisation
  mm: Add PG_arch_3 page flag
  KVM: arm64: Simplify the sanitise_mte_tags() logic
  arm64: mte: Fix/clarify the PG_mte_tagged semantics
  mm: Do not enable PG_arch_2 for all 64-bit architectures

Signed-off-by: Marc Zyngier <maz@kernel.org>
2022-12-05 14:38:24 +00:00
David Matlack 34e30ebbe4 KVM: Document the interaction between KVM_CAP_HALT_POLL and halt_poll_ns
Clarify the existing documentation about how KVM_CAP_HALT_POLL and
halt_poll_ns interact to make it clear that VMs using KVM_CAP_HALT_POLL
ignore halt_poll_ns.

Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20221201195249.3369720-3-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-02 13:20:30 -05:00
David Matlack b8b43a4c2e KVM: Move halt-polling documentation into common directory
Move halt-polling.rst into the common KVM documentation directory and
out of the x86-specific directory. Halt-polling is a common feature and
the existing documentation is already written as such.

Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20221201195249.3369720-2-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-02 13:20:30 -05:00
Paolo Bonzini b376144595 Misc KVM x86 fixes and cleanups for 6.2:
- One-off fixes for various emulation flows (SGX, VMXON, NRIPS=0).
 
  - Reinstate IBPB on emulated VM-Exit that was incorrectly dropped a few
    years back when eliminating unnecessary barriers when switching between
    vmcs01 and vmcs02.
 
  - Clean up the MSR filter docs.
 
  - Clean up vmread_error_trampoline() to make it more obvious that params
    must be passed on the stack, even for x86-64.
 
  - Let userspace set all supported bits in MSR_IA32_FEAT_CTL irrespective
    of the current guest CPUID.
 
  - Fudge around a race with TSC refinement that results in KVM incorrectly
    thinking a guest needs TSC scaling when running on a CPU with a
    constant TSC, but no hardware-enumerated TSC frequency.
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Merge tag 'kvm-x86-fixes-6.2-1' of https://github.com/kvm-x86/linux into HEAD

Misc KVM x86 fixes and cleanups for 6.2:

 - One-off fixes for various emulation flows (SGX, VMXON, NRIPS=0).

 - Reinstate IBPB on emulated VM-Exit that was incorrectly dropped a few
   years back when eliminating unnecessary barriers when switching between
   vmcs01 and vmcs02.

 - Clean up the MSR filter docs.

 - Clean up vmread_error_trampoline() to make it more obvious that params
   must be passed on the stack, even for x86-64.

 - Let userspace set all supported bits in MSR_IA32_FEAT_CTL irrespective
   of the current guest CPUID.

 - Fudge around a race with TSC refinement that results in KVM incorrectly
   thinking a guest needs TSC scaling when running on a CPU with a
   constant TSC, but no hardware-enumerated TSC frequency.
2022-12-02 12:56:25 -05:00
Javier Martinez Canillas 10c5e80b2c KVM: Add missing arch for KVM_CREATE_DEVICE and KVM_{SET,GET}_DEVICE_ATTR
The ioctls are missing an architecture property that is present in others.

Suggested-by: Sergio Lopez Pascual <slp@redhat.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Message-Id: <20221202105011.185147-5-javierm@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-02 12:54:41 -05:00
Javier Martinez Canillas 30ee198ce4 KVM: Reference to kvm_userspace_memory_region in doc and comments
There are still references to the removed kvm_memory_region data structure
but the doc and comments should mention struct kvm_userspace_memory_region
instead, since that is what's used by the ioctl that replaced the old one
and this data structure support the same set of flags.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Message-Id: <20221202105011.185147-4-javierm@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-02 12:54:40 -05:00
Javier Martinez Canillas 66a9221d73 KVM: Delete all references to removed KVM_SET_MEMORY_ALIAS ioctl
The documentation says that the ioctl has been deprecated, but it has been
actually removed and the remaining references are just left overs.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Message-Id: <20221202105011.185147-3-javierm@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-02 12:54:40 -05:00
Javier Martinez Canillas 61e15f8712 KVM: Delete all references to removed KVM_SET_MEMORY_REGION ioctl
The documentation says that the ioctl has been deprecated, but it has been
actually removed and the remaining references are just left overs.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Message-Id: <20221202105011.185147-2-javierm@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-02 12:54:30 -05:00
Sean Christopherson 1f15814718 KVM: x86: Clean up KVM_CAP_X86_USER_SPACE_MSR documentation
Clean up the KVM_CAP_X86_USER_SPACE_MSR documentation to eliminate
misleading and/or inconsistent verbiage, and to actually document what
accesses are intercepted by which flags.

  - s/will/may since not all #GPs are guaranteed to be intercepted
  - s/deflect/intercept to align with common KVM terminology
  - s/user space/userspace to align with the majority of KVM docs
  - Avoid using "trap" terminology, as KVM exits to userspace _before_
    stepping, i.e. doesn't exhibit trap-like behavior
  - Actually document the flags

Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20220831001706.4075399-4-seanjc@google.com
2022-11-30 16:19:43 -08:00
Sean Christopherson b93d2ec34e KVM: x86: Reword MSR filtering docs to more precisely define behavior
Reword the MSR filtering documentatiion to more precisely define the
behavior of filtering using common virtualization terminology.

  - Explicitly document KVM's behavior when an MSR is denied
  - s/handled/allowed as there is no guarantee KVM will "handle" the
    MSR access
  - Drop the "fall back" terminology, which incorrectly suggests that
    there is existing KVM behavior to fall back to
  - Fix an off-by-one error in the range (the end is exclusive)
  - Call out the interaction between MSR filtering and
    KVM_CAP_X86_USER_SPACE_MSR's KVM_MSR_EXIT_REASON_FILTER
  - Delete the redundant paragraph on what '0' and '1' in the bitmap
    means, it's covered by the sections on KVM_MSR_FILTER_{READ,WRITE}
  - Delete the clause on x2APIC MSR behavior depending on APIC base, this
    is covered by stating that KVM follows architectural behavior when
    emulating/virtualizing MSR accesses

Reported-by: Aaron Lewis <aaronlewis@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20220831001706.4075399-3-seanjc@google.com
2022-11-30 16:19:43 -08:00
Sean Christopherson 5c8c0b3273 KVM: x86: Delete documentation for READ|WRITE in KVM_X86_SET_MSR_FILTER
Delete the paragraph that describes the behavior when both
KVM_MSR_FILTER_READ | KVM_MSR_FILTER_WRITE are set for a range.  There is
nothing special about KVM's handling of this combination, whereas
explicitly documenting the combination suggests that there is some magic
behavior the user needs to be aware of.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20220831001706.4075399-2-seanjc@google.com
2022-11-30 16:19:43 -08:00
David Woodhouse d8ba8ba4c8 KVM: x86/xen: Allow XEN_RUNSTATE_UPDATE flag behaviour to be configured
Closer inspection of the Xen code shows that we aren't supposed to be
using the XEN_RUNSTATE_UPDATE flag unconditionally. It should be
explicitly enabled by guests through the HYPERVISOR_vm_assist hypercall.
If we randomly set the top bit of ->state_entry_time for a guest that
hasn't asked for it and doesn't expect it, that could make the runtimes
fail to add up and confuse the guest. Without the flag it's perfectly
safe for a vCPU to read its own vcpu_runstate_info; just not for one
vCPU to read *another's*.

I briefly pondered adding a word for the whole set of VMASST_TYPE_*
flags but the only one we care about for HVM guests is this, so it
seemed a bit pointless.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20221127122210.248427-3-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-30 10:59:37 -05:00
Peter Collingbourne a4baf8d263 Documentation: document the ABI changes for KVM_CAP_ARM_MTE
Document both the restriction on VM_MTE_ALLOWED mappings and
the relaxation for shared mappings.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221104011041.290951-9-pcc@google.com
2022-11-29 09:26:07 +00:00
Paolo Bonzini 1e79a9e3ab - Second batch of the lazy destroy patches
- First batch of KVM changes for kernel virtual != physical address support
 - Removal of a unused function
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Merge tag 'kvm-s390-next-6.2-1' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

- Second batch of the lazy destroy patches
- First batch of KVM changes for kernel virtual != physical address support
- Removal of a unused function
2022-11-28 13:34:47 -05:00
Claudio Imbrenda d9459922a1 KVM: s390: pv: api documentation for asynchronous destroy
Add documentation for the new commands added to the KVM_S390_PV_COMMAND
ioctl.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Nico Boehr <nrb@linux.ibm.com>
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Link: https://lore.kernel.org/r/20221111170632.77622-3-imbrenda@linux.ibm.com
Message-Id: <20221111170632.77622-3-imbrenda@linux.ibm.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
2022-11-23 09:06:50 +00:00