If mmu_lock is held for write, don't bother setting !PRESENT SPTEs to
REMOVED_SPTE when recursively zapping SPTEs as part of shadow page
removal. The concurrent write protections provided by REMOVED_SPTE are
not needed, there are no backing page side effects to record, and MMIO
SPTEs can be left as is since they are protected by the memslot
generation, not by ensuring that the MMIO SPTE is unreachable (which
is racy with respect to lockless walks regardless of zapping behavior).
Skipping !PRESENT drastically reduces the number of updates needed to
tear down sparsely populated MMUs, e.g. when tearing down a 6gb VM that
didn't touch much memory, 6929/7168 (~96.6%) of SPTEs were '0' and could
be skipped.
Avoiding the write itself is likely close to a wash, but avoiding
__handle_changed_spte() is a clear-cut win as that involves saving and
restoring all non-volatile GPRs (it's a subtly big function), as well as
several conditional branches before bailing out.
Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210310003029.1250571-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
# lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 88
On-line CPU(s) list: 0-63
Off-line CPU(s) list: 64-87
# cat /proc/cmdline
BOOT_IMAGE=/vmlinuz-5.10.0-rc3-tlinux2-0050+ root=/dev/mapper/cl-root ro
rd.lvm.lv=cl/root rhgb quiet console=ttyS0 LANG=en_US .UTF-8 no-kvmclock-vsyscall
# echo 1 > /sys/devices/system/cpu/cpu76/online
-bash: echo: write error: Cannot allocate memory
The per-cpu vsyscall pvclock data pointer assigns either an element of the
static array hv_clock_boot (#vCPU <= 64) or dynamically allocated memory
hvclock_mem (vCPU > 64), the dynamically memory will not be allocated if
kvmclock vsyscall is disabled, this can result in cpu hotpluged fails in
kvmclock_setup_percpu() which returns -ENOMEM. It's broken for no-vsyscall
and sometimes you end up with vsyscall disabled if the host does something
strange. This patch fixes it by allocating this dynamically memory
unconditionally even if vsyscall is disabled.
Fixes: 6a1cac56f4 ("x86/kvm: Use __bss_decrypted attribute in shared variables")
Reported-by: Zelin Deng <zelin.deng@linux.alibaba.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: stable@vger.kernel.org#v4.19-rc5+
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1614130683-24137-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Directly connect the 'npt' param to the 'npt_enabled' variable so that
runtime adjustments to npt_enabled are reflected in sysfs. Move the
!PAE restriction to a runtime check to ensure NPT is forced off if the
host is using 2-level paging, and add a comment explicitly stating why
NPT requires a 64-bit kernel or a kernel with PAE enabled.
Opportunistically switch the param to octal permissions.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305021637.3768573-1-seanjc@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When posting a deadline timer interrupt, open code the checks guarding
__kvm_wait_lapic_expire() in order to skip the lapic_timer_int_injected()
check in kvm_wait_lapic_expire(). The injection check will always fail
since the interrupt has not yet be injected. Moving the call after
injection would also be wrong as that wouldn't actually delay delivery
of the IRQ if it is indeed sent via posted interrupt.
Fixes: 010fd37fdd ("KVM: LAPIC: Reduce world switch latency caused by timer_advance_ns")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305021808.3769732-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This problem was reported on a SVM guest while executing kexec.
Kexec fails to load the new kernel when the PCID feature is enabled.
When kexec starts loading the new kernel, it starts the process by
resetting the vCPU's and then bringing each vCPU online one by one.
The vCPU reset is supposed to reset all the register states before the
vCPUs are brought online. However, the CR4 register is not reset during
this process. If this register is already setup during the last boot,
all the flags can remain intact. The X86_CR4_PCIDE bit can only be
enabled in long mode. So, it must be enabled much later in SMP
initialization. Having the X86_CR4_PCIDE bit set during SMP boot can
cause a boot failures.
Fix the issue by resetting the CR4 register in init_vmcb().
Signed-off-by: Babu Moger <babu.moger@amd.com>
Message-Id: <161471109108.30811.6392805173629704166.stgit@bmoger-ubuntu>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This is how Xen guests do steal time accounting. The hypervisor records
the amount of time spent in each of running/runnable/blocked/offline
states.
In the Xen accounting, a vCPU is still in state RUNSTATE_running while
in Xen for a hypercall or I/O trap, etc. Only if Xen explicitly schedules
does the state become RUNSTATE_blocked. In KVM this means that even when
the vCPU exits the kvm_run loop, the state remains RUNSTATE_running.
The VMM can explicitly set the vCPU to RUNSTATE_blocked by using the
KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_CURRENT attribute, and can also use
KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST to retrospectively add a given
amount of time to the blocked state and subtract it from the running
state.
The state_entry_time corresponds to get_kvmclock_ns() at the time the
vCPU entered the current state, and the total times of all four states
should always add up to state_entry_time.
Co-developed-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20210301125309.874953-2-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When clearing the per-vCPU shared regions, set the return value to zero
to indicate success. This was causing spurious errors to be returned to
userspace on soft reset.
Also add a paranoid BUILD_BUG_ON() for compat structure compatibility.
Fixes: 0c165b3c01 ("KVM: x86/xen: Allow reset of Xen attributes")
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20210301125309.874953-1-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The Xen hypercall interface adds to the attack surface of the hypervisor
and will be used quite rarely. Allow compiling it out.
Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
A missing flush would cause the static branch to trigger incorrectly.
Cc: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Check that PML is actually enabled before setting the mask to force a
SPTE to be write-protected. The bits used for the !AD_ENABLED case are
in the upper half of the SPTE. With 64-bit paging and EPT, these bits
are ignored, but with 32-bit PAE paging they are reserved. Setting them
for L2 SPTEs without checking PML breaks NPT on 32-bit KVM.
Fixes: 1f4e5fc83a ("KVM: x86: fix nested guest live migration with PML")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210225204749.1512652-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The 'mmu_page_hash' is used as hash table while 'active_mmu_pages' is a
list. Remove the misplaced comment as it's mostly stating the obvious
anyways.
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210226061945.1222-1-dongli.zhang@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Fix the interpreation of nested_svm_vmexit()'s return value when
synthesizing a nested VM-Exit after intercepting an SVM instruction while
L2 was running. The helper returns '0' on success, whereas a return
value of '0' in the exit handler path means "exit to userspace". The
incorrect return value causes KVM to exit to userspace without filling
the run state, e.g. QEMU logs "KVM: unknown exit, hardware reason 0".
Fixes: 14c2bf81fc ("KVM: SVM: Fix #GP handling for doubly-nested virtualization")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210224005627.657028-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
If lbr_desc->event is successfully created, the intel_pmu_create_
guest_lbr_event() will return 0, otherwise it will return -ENOENT,
and then jump to LBR msrs dummy handling.
Fixes: 1b5ac3226a ("KVM: vmx/pmu: Pass-through LBR msrs when the guest LBR event is ACTIVE")
Signed-off-by: Like Xu <like.xu@linux.intel.com>
Message-Id: <20210223013958.1280444-1-like.xu@linux.intel.com>
[Add "< 0" and PTR_ERR to make the code clearer. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Track the range being invalidated by mmu_notifier and skip page fault
retries if the fault address is not affected by the in-progress
invalidation. Handle concurrent invalidations by finding the minimal
range which includes all ranges being invalidated. Although the combined
range may include unrelated addresses and cannot be shrunk as individual
invalidation operations complete, it is unlikely the marginal gains of
proper range tracking are worth the additional complexity.
The primary benefit of this change is the reduction in the likelihood of
extreme latency when handing a page fault due to another thread having
been preempted while modifying host virtual addresses.
Signed-off-by: David Stevens <stevensd@chromium.org>
Message-Id: <20210222024522.1751719-3-stevensd@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Don't retry a page fault due to an mmu_notifier invalidation when
handling a page fault for a GPA that did not resolve to a memslot, i.e.
an MMIO page fault. Invalidations from the mmu_notifier signal a change
in a host virtual address (HVA) mapping; without a memslot, there is no
HVA and thus no possibility that the invalidation is relevant to the
page fault being handled.
Note, the MMIO vs. memslot generation checks handle the case where a
pending memslot will create a memslot overlapping the faulting GPA. The
mmu_notifier checks are orthogonal to memslot updates.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210222024522.1751719-2-stevensd@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Right now, enter_svm_guest_mode is calling nested_prepare_vmcb_save and
nested_prepare_vmcb_control. This results in is_guest_mode being false
until the end of nested_prepare_vmcb_control.
This is a problem because nested_prepare_vmcb_save can in turn cause
changes to the intercepts and these have to be applied to the "host VMCB"
(stored in svm->nested.hsave) and then merged with the VMCB12 intercepts
into svm->vmcb.
In particular, without this change we forget to set the CR0 read and CR0
write intercepts when running a real mode L2 guest with NPT disabled.
The guest is therefore able to see the CR0.PG bit that KVM sets to
enable "paged real mode". This patch fixes the svm.flat mode_switch
test case with npt=0. There are no other problematic calls in
nested_prepare_vmcb_save.
Moving is_guest_mode to the end is done since commit 06fc777269
("KVM: SVM: Activate nested state only when guest state is complete",
2010-04-25). However, back then KVM didn't grab a different VMCB
when updating the intercepts, it had already copied/merged L1's stuff
to L0's VMCB, and then updated L0's VMCB regardless of is_nested().
Later recalc_intercepts was introduced in commit 384c636843
("KVM: SVM: Add function to recalculate intercept masks", 2011-01-12).
This introduced the bug, because recalc_intercepts now throws away
the intercept manipulations that svm_set_cr0 had done in the meanwhile
to svm->vmcb.
[1] https://lore.kernel.org/kvm/1266493115-28386-1-git-send-email-joerg.roedel@amd.com/
Reviewed-by: Sean Christopherson <seanjc@google.com>
Tested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove several exports from the MMU that are no longer necessary.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210213005015.1651772-15-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Drop kvm_mmu_slot_largepage_remove_write_access() and refactor its sole
caller to use kvm_mmu_slot_remove_write_access(). Remove the now-unused
slot_handle_large_level() and slot_handle_all_level() helpers.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210213005015.1651772-14-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Stop setting dirty bits for MMU pages when dirty logging is disabled for
a memslot, as PML is now completely disabled when there are no memslots
with dirty logging enabled.
This means that spurious PML entries will be created for memslots with
dirty logging disabled if at least one other memslot has dirty logging
enabled. However, spurious PML entries are already possible since
dirty bits are set only when a dirty logging is turned off, i.e. memslots
that are never dirty logged will have dirty bits cleared.
In the end, it's faster overall to eat a few spurious PML entries in the
window where dirty logging is being disabled across all memslots.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210213005015.1651772-13-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Currently, if enable_pml=1 PML remains enabled for the entire lifetime
of the VM irrespective of whether dirty logging is enable or disabled.
When dirty logging is disabled, all the pages of the VM are manually
marked dirty, so that PML is effectively non-operational. Setting
the dirty bits is an expensive operation which can cause severe MMU
lock contention in a performance sensitive path when dirty logging is
disabled after a failed or canceled live migration.
Manually setting dirty bits also fails to prevent PML activity if some
code path clears dirty bits, which can incur unnecessary VM-Exits.
In order to avoid this extra overhead, dynamically enable/disable PML
when dirty logging gets turned on/off for the first/last memslot.
Signed-off-by: Makarand Sonare <makarandsonare@google.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210213005015.1651772-12-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a sanity check in kvm_mmu_slot_apply_flags to assert that the
LOG_DIRTY_PAGES flag is indeed being toggled, and explicitly rely on
that holding true when zapping collapsible SPTEs. Manipulating the
CPU dirty log (PML) and write-protection also relies on this assertion,
but that's not obvious in the current code.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210213005015.1651772-11-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Drop the facade of KVM's PML logic being vendor specific and move the
bits that aren't truly VMX specific into common x86 code. The MMU logic
for dealing with PML is tightly coupled to the feature and to VMX's
implementation, bouncing through kvm_x86_ops obfuscates the code without
providing any meaningful separation of concerns or encapsulation.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210213005015.1651772-10-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Store the vendor-specific dirty log size in a variable, there's no need
to wrap it in a function since the value is constant after
hardware_setup() runs.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210213005015.1651772-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Expand the comment about need to use write-protection for nested EPT
when PML is enabled to clarify that the tagging is a nop when PML is
_not_ enabled. Without the clarification, omitting the PML check looks
wrong at first^Wfifth glance.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210213005015.1651772-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Unconditionally disable PML in vmcs02, KVM emulates PML purely in the
MMU, e.g. vmx_flush_pml_buffer() doesn't even try to copy the L2 GPAs
from vmcs02's buffer to vmcs12. At best, enabling PML is a nop. At
worst, it will cause vmx_flush_pml_buffer() to record bogus GFNs in the
dirty logs.
Initialize vmcs02.GUEST_PML_INDEX such that PML writes would trigger
VM-Exit if PML was somehow enabled, skip flushing the buffer for guest
mode since the index is bogus, and freak out if a PML full exit occurs
when L2 is active.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210213005015.1651772-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When zapping SPTEs in order to rebuild them as huge pages, use the new
helper that computes the max mapping level to detect whether or not a
SPTE should be zapped. Doing so avoids zapping SPTEs that can't
possibly be rebuilt as huge pages, e.g. due to hardware constraints,
memslot alignment, etc...
This also avoids zapping SPTEs that are still large, e.g. if migration
was canceled before write-protected huge pages were shattered to enable
dirty logging. Note, such pages are still write-protected at this time,
i.e. a page fault VM-Exit will still occur. This will hopefully be
addressed in a future patch.
Sadly, TDP MMU loses its const on the memslot, but that's a pervasive
problem that's been around for quite some time.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210213005015.1651772-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pass the memslot to the rmap callbacks, it will be used when zapping
collapsible SPTEs to verify the memslot is compatible with hugepages
before zapping its SPTEs.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210213005015.1651772-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Factor out the logic for determining the maximum mapping level given a
memslot and a gpa. The helper will be used when zapping collapsible
SPTEs when disabling dirty logging, e.g. to avoid zapping SPTEs that
can't possibly be rebuilt as hugepages.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210213005015.1651772-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Zap SPTEs that are backed by ZONE_DEVICE pages when zappings SPTEs to
rebuild them as huge pages in the TDP MMU. ZONE_DEVICE huge pages are
managed differently than "regular" pages and are not compound pages.
Likewise, PageTransCompoundMap() will not detect HugeTLB, so switch
to PageCompound().
This matches the similar check in kvm_mmu_zap_collapsible_spte.
Cc: Ben Gardon <bgardon@google.com>
Fixes: 1488199856 ("kvm: x86/mmu: Support disabling dirty logging for the tdp MMU")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210213005015.1651772-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This is not needed because the tweak was done on the guest_mmu, while
nested_ept_uninit_mmu_context has just changed vcpu->arch.walk_mmu
back to the root_mmu.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In case of npt=0 on host, nSVM needs the same .inject_page_fault tweak
as VMX has, to make sure that shadow mmu faults are injected as vmexits.
It is not clear why this is needed at all, but for now keep the same
code as VMX and we'll fix it for both.
Based on a patch by Maxim Levitsky <mlevitsk@redhat.com>.
Fixes: 7c86663b68 ("KVM: nSVM: inject exceptions via svm_check_nested_events")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This way trace will capture all the nested mode entries
(including entries after migration, and from smm)
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210217145718.1217358-3-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
trace_kvm_exit prints this value (using vmx_get_exit_info)
so it makes sense to read it before the trace point.
Fixes: dcf068da7e ("KVM: VMX: Introduce generic fastpath handler")
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210217145718.1217358-2-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove the restriction that prevents VMX from exposing INVPCID to the
guest without PCID also being exposed to the guest. The justification of
the restriction is that INVPCID will #UD if it's disabled in the VMCS.
While that is a true statement, it's also true that RDTSCP will #UD if
it's disabled in the VMCS. Neither of those things has any dependency
whatsoever on the guest being able to set CR4.PCIDE=1, which is what is
effectively allowed by exposing PCID to the guest.
Removing the bogus restriction aligns VMX with SVM, and also allows for
an interesting configuration. INVPCID is that fastest way to do a global
TLB flush, e.g. see native_flush_tlb_global(). Allowing INVPCID without
PCID would let a guest use the expedited flush while also limiting the
number of ASIDs consumed by the guest.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210212003411.1102677-4-seanjc@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Advertise INVPCID by default (if supported by the host kernel) instead
of having both SVM and VMX opt in. INVPCID was opt in when it was a
VMX only feature so that KVM wouldn't prematurely advertise support
if/when it showed up in the kernel on AMD hardware.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210212003411.1102677-3-seanjc@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Intercept INVPCID if it's disabled in the guest, even when using NPT,
as KVM needs to inject #UD in this case.
Fixes: 4407a797e9 ("KVM: SVM: Enable INVPCID feature on AMD")
Cc: Babu Moger <babu.moger@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210212003411.1102677-2-seanjc@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
- Make the nVHE EL2 object relocatable, resulting in much more
maintainable code
- Handle concurrent translation faults hitting the same page
in a more elegant way
- Support for the standard TRNG hypervisor call
- A bunch of small PMU/Debug fixes
- Allow the disabling of symbol export from assembly code
- Simplification of the early init hypercall handling
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Merge tag 'kvmarm-5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm64 updates for Linux 5.12
- Make the nVHE EL2 object relocatable, resulting in much more
maintainable code
- Handle concurrent translation faults hitting the same page
in a more elegant way
- Support for the standard TRNG hypervisor call
- A bunch of small PMU/Debug fixes
- Allow the disabling of symbol export from assembly code
- Simplification of the early init hypercall handling
Add a 2 byte pad to struct compat_vcpu_info so that the sum size of its
fields is actually 64 bytes. The effective size without the padding is
also 64 bytes due to the compiler aligning evtchn_pending_sel to a 4-byte
boundary, but depending on compiler alignment is subtle and unnecessary.
Opportunistically replace spaces with tables in the other fields.
Cc: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210210182609.435200-6-seanjc@google.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The sparse tool complains as follows:
arch/x86/kvm/svm/svm.c:204:6: warning:
symbol 'svm_gp_erratum_intercept' was not declared. Should it be static?
This symbol is not used outside of svm.c, so this
commit marks it static.
Fixes: 82a11e9c6f ("KVM: SVM: Add emulation support for #GP triggered by SVM instructions")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Message-Id: <20210210075958.1096317-1-weiyongjun1@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In order to support Xen SHUTDOWN_soft_reset (for guest kexec, etc.) the
VMM needs to be able to tear everything down and return the Xen features
to a clean slate.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20210208232326.1830370-1-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When retpolines are enabled they have high overhead in the inner loop
inside kvm_handle_hva_range() that iterates over the provided memory area.
Let's mark this function and its TDP MMU equivalent __always_inline so
compiler will be able to change the call to the actual handler function
inside each of them into a direct one.
This significantly improves performance on the unmap test on the existing
kernel memslot code (tested on a Xeon 8167M machine):
30 slots in use:
Test Before After Improvement
Unmap 0.0353s 0.0334s 5%
Unmap 2M 0.00104s 0.000407s 61%
509 slots in use:
Test Before After Improvement
Unmap 0.0742s 0.0740s None
Unmap 2M 0.00221s 0.00159s 28%
Looks like having an indirect call in these functions (and, so, a
retpoline) might have interfered with unrolling of the whole loop in the
CPU.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <732d3fe9eb68aa08402a638ab0309199fa89ae56.1612810129.git.maciej.szmigiero@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
hv_vcpu_to_vcpu() helper is only used by other helpers and
is not very complex, we can drop it without much regret.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210126134816.1880136-16-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Hyper-V context is only needed for guests which use Hyper-V emulation in
KVM (e.g. Windows/Hyper-V guests) so we don't actually need to allocate
it in kvm_arch_vcpu_create(), we can postpone the action until Hyper-V
specific MSRs are accessed or SynIC is enabled.
Once allocated, let's keep the context alive for the lifetime of the vCPU
as an attempt to free it would require additional synchronization with
other vCPUs and normally it is not supposed to happen.
Note, Hyper-V style hypercall enablement is done by writing to
HV_X64_MSR_GUEST_OS_ID so we don't need to worry about allocating Hyper-V
context from kvm_hv_hypercall().
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210126134816.1880136-15-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Hyper-V emulation is enabled in KVM unconditionally. This is bad at least
from security standpoint as it is an extra attack surface. Ideally, there
should be a per-VM capability explicitly enabled by VMM but currently it
is not the case and we can't mandate one without breaking backwards
compatibility. We can, however, check guest visible CPUIDs and only enable
Hyper-V emulation when "Hv#1" interface was exposed in
HYPERV_CPUID_INTERFACE.
Note, VMMs are free to act in any sequence they like, e.g. they can try
to set MSRs first and CPUIDs later so we still need to allow the host
to read/write Hyper-V specific MSRs unconditionally.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210126134816.1880136-14-vkuznets@redhat.com>
[Add selftest vcpu_set_hv_cpuid API to avoid breaking xen_vmcall_test. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Hyper-V context is only needed for guests which use Hyper-V emulation in
KVM (e.g. Windows/Hyper-V guests). 'struct kvm_vcpu_hv' is, however, quite
big, it accounts for more than 1/4 of the total 'struct kvm_vcpu_arch'
which is also quite big already. This all looks like a waste.
Allocate 'struct kvm_vcpu_hv' dynamically. This patch does not bring any
(intentional) functional change as we still allocate the context
unconditionally but it paves the way to doing that only when needed.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210126134816.1880136-13-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Currently, Hyper-V context is part of 'struct kvm_vcpu_arch' and is always
available. As a preparation to allocating it dynamically, check that it is
not NULL at call sites which can normally proceed without it i.e. the
behavior is identical to the situation when Hyper-V emulation is not being
used by the guest.
When Hyper-V context for a particular vCPU is not allocated, we may still
need to get 'vp_index' from there. E.g. in a hypothetical situation when
Hyper-V emulation was enabled on one CPU and wasn't on another, Hyper-V
style send-IPI hypercall may still be used. Luckily, vp_index is always
initialized to kvm_vcpu_get_idx() and can only be changed when Hyper-V
context is present. Introduce kvm_hv_get_vpindex() helper for
simplification.
No functional change intended.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210126134816.1880136-12-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
As a preparation to allocating Hyper-V context dynamically, make it clear
who's the user of the said context.
No functional change intended.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210126134816.1880136-11-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson