Neither AMD nor Intel CPUs have an EFER field in the legacy SMRAM save
state area, i.e. don't save/restore EFER across SMM transitions. KVM
somewhat models this, e.g. doesn't clear EFER on entry to SMM if the
guest doesn't support long mode. But during RSM, KVM unconditionally
clears EFER so that it can get back to pure 32-bit mode in order to
start loading CRs with their actual non-SMM values.
Clear EFER only when it will be written when loading the non-SMM state
so as to preserve bits that can theoretically be set on 32-bit vCPUs,
e.g. KVM always emulates EFER_SCE.
And because CR4.PAE is cleared only to play nice with EFER, wrap that
code in the long mode check as well. Note, this may result in a
compiler warning about cr4 being consumed uninitialized. Re-read CR4
even though it's technically unnecessary, as doing so allows for more
readable code and RSM emulation is not a performance critical path.
Fixes: 660a5d517a ("KVM: x86: save/load state on SMM switch")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
RSM emulation is currently broken on VMX when the interrupted guest has
CR4.VMXE=1. Stop dancing around the issue of HF_SMM_MASK being set when
loading SMSTATE into architectural state, e.g. by toggling it for
problematic flows, and simply clear HF_SMM_MASK prior to loading
architectural state (from SMRAM save state area).
Reported-by: Jon Doron <arilou@gmail.com>
Cc: Jim Mattson <jmattson@google.com>
Cc: Liran Alon <liran.alon@oracle.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Fixes: 5bea5123cb ("KVM: VMX: check nested state and CR4.VMXE against SMM")
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Tested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Prepare for clearing HF_SMM_MASK prior to loading state from the SMRAM
save state map, i.e. kvm_smm_changed() needs to be called after state
has been loaded and so cannot be done automatically when setting
hflags from RSM.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
RSM emulation is currently broken on VMX when the interrupted guest has
CR4.VMXE=1. Rather than dance around the issue of HF_SMM_MASK being set
when loading SMSTATE into architectural state, ideally RSM emulation
itself would be reworked to clear HF_SMM_MASK prior to loading non-SMM
architectural state.
Ostensibly, the only motivation for having HF_SMM_MASK set throughout
the loading of state from the SMRAM save state area is so that the
memory accesses from GET_SMSTATE() are tagged with role.smm. Load
all of the SMRAM save state area from guest memory at the beginning of
RSM emulation, and load state from the buffer instead of reading guest
memory one-by-one.
This paves the way for clearing HF_SMM_MASK prior to loading state,
and also aligns RSM with the enter_smm() behavior, which fills a
buffer and writes SMRAM save state in a single go.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Currently, CONFIG_JUMP_LABEL just means "I _want_ to use jump label".
The jump label is controlled by HAVE_JUMP_LABEL, which is defined
like this:
#if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL)
# define HAVE_JUMP_LABEL
#endif
We can improve this by testing 'asm goto' support in Kconfig, then
make JUMP_LABEL depend on CC_HAS_ASM_GOTO.
Ugly #ifdef HAVE_JUMP_LABEL will go away, and CONFIG_JUMP_LABEL will
match to the real kernel capability.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
"sizeof(x)" is the canonical coding style used in arch/x86 most of the time.
Fix the few places that didn't follow the convention.
(Also do some whitespace cleanups in a few places while at it.)
[ mingo: Rewrote the changelog. ]
Signed-off-by: Jordan Borgner <mail@jordan-borgner.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20181028125828.7rgammkgzep2wpam@JordanDesktop
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It is a duplicate of X86_CR3_PCID_NOFLUSH. So just use that instead.
Signed-off-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The functions that were used in the emulation of fxrstor, fxsave, sgdt and
sidt were originally meant for task switching, and as such they did not
check privilege levels. This is very bad when the same functions are used
in the emulation of unprivileged instructions. This is CVE-2018-10853.
The obvious fix is to add a new argument to ops->read_std and ops->write_std,
which decides whether the access is a "system" access or should use the
processor's CPL.
Fixes: 129a72a0d3 ("KVM: x86: Introduce segmented_write_std", 2017-01-12)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Wrap the common invocation of ctxt->ops->read_std and ctxt->ops->write_std, so
as to have a smaller patch when the functions grow another argument.
Fixes: 129a72a0d3 ("KVM: x86: Introduce segmented_write_std", 2017-01-12)
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
MSB of CR3 is a reserved bit if the PCIDE bit is not set in CR4.
It should be checked when PCIDE bit is not set, however commit
'd1cd3ce900441 ("KVM: MMU: check guest CR3 reserved bits based on
its physical address width")' removes the bit 63 checking
unconditionally. This patch fixes it by checking bit 63 of CR3
when PCIDE bit is not set in CR4.
Fixes: d1cd3ce900 (KVM: MMU: check guest CR3 reserved bits based on its physical address width)
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Liran Alon <liran.alon@oracle.com>
Cc: stable@vger.kernel.org
Reviewed-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This is very similar to the aligned versions movaps/movapd.
We have seen the corresponding emulation failures with openbsd as guest
and with Windows 10 with intel HD graphics pass through.
Signed-off-by: Christian Ehrhardt <christian_ehrhardt@genua.de>
Signed-off-by: Stefan Fritsch <sf@sfritsch.de>
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
VMware exposes the following Pseudo PMCs:
0x10000: Physical host TSC
0x10001: Elapsed real time in ns
0x10002: Elapsed apparent time in ns
For more info refer to:
https://www.vmware.com/files/pdf/techpaper/Timekeeping-In-VirtualMachines.pdf
VMware allows access to these Pseduo-PMCs even when read via RDPMC
in Ring3 and CR4.PCE=0. Therefore, commit modifies x86 emulator
to allow access to these PMCs in this situation. In addition,
emulation of these PMCs were added to kvm_pmu_rdpmc().
Signed-off-by: Arbel Moshe <arbel.moshe@oracle.com>
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pull x86/pti updates from Thomas Gleixner:
"Another set of melted spectrum related changes:
- Code simplifications and cleanups for RSB and retpolines.
- Make the indirect calls in KVM speculation safe.
- Whitelist CPUs which are known not to speculate from Meltdown and
prepare for the new CPUID flag which tells the kernel that a CPU is
not affected.
- A less rigorous variant of the module retpoline check which merily
warns when a non-retpoline protected module is loaded and reflects
that fact in the sysfs file.
- Prepare for Indirect Branch Prediction Barrier support.
- Prepare for exposure of the Speculation Control MSRs to guests, so
guest OSes which depend on those "features" can use them. Includes
a blacklist of the broken microcodes. The actual exposure of the
MSRs through KVM is still being worked on"
* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/speculation: Simplify indirect_branch_prediction_barrier()
x86/retpoline: Simplify vmexit_fill_RSB()
x86/cpufeatures: Clean up Spectre v2 related CPUID flags
x86/cpu/bugs: Make retpoline module warning conditional
x86/bugs: Drop one "mitigation" from dmesg
x86/nospec: Fix header guards names
x86/alternative: Print unadorned pointers
x86/speculation: Add basic IBPB (Indirect Branch Prediction Barrier) support
x86/cpufeature: Blacklist SPEC_CTRL/PRED_CMD on early Spectre v2 microcodes
x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown
x86/msr: Add definitions for new speculation control MSRs
x86/cpufeatures: Add AMD feature bits for Speculation Control
x86/cpufeatures: Add Intel feature bits for Speculation Control
x86/cpufeatures: Add CPUID_7_EDX CPUID leaf
module/retpoline: Warn about missing retpoline in module
KVM: VMX: Make indirect call speculation safe
KVM: x86: Make indirect calls in emulator speculation safe
Replace the indirect calls with CALL_NOSPEC.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Jun Nakajima <jun.nakajima@intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: rga@amazon.de
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Asit Mallick <asit.k.mallick@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Arjan Van De Ven <arjan.van.de.ven@intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Link: https://lkml.kernel.org/r/20180125095843.595615683@infradead.org
rsm_load_state_64() and rsm_enter_protected_mode() load CR3, then
CR4 & ~PCIDE, then CR0, then CR4.
However, setting CR4.PCIDE fails if CR3[11:0] != 0. It's probably easier
in the long run to replace rsm_enter_protected_mode() with an emulator
callback that sets all the special registers (like KVM_SET_SREGS would
do). For now, set the PCID field of CR3 only after CR4.PCIDE is 1.
Reported-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Fixes: 660a5d517a
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This is encoded as F3 0F C7 /7 with a register argument. The register
argument is the second array in the group9 GroupDual, while F3 is the
fourth element of a Prefix.
Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
These are needed to handle the descriptor table vmexits when emulating
UMIP.
Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add the CPUID bits, make the CR4.UMIP bit not reserved anymore, and
add UMIP support for instructions that are already emulated by KVM.
Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Now that get_fpu and put_fpu do nothing, because the scheduler will
automatically load and restore the guest FPU context for us while we
are in this code (deep inside the vcpu_run main loop), we can get rid
of the get_fpu and put_fpu hooks.
Signed-off-by: Rik van Riel <riel@redhat.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pedro reported:
During tests that we conducted on KVM, we noticed that executing a "PUSH %ES"
instruction under KVM produces different results on both memory and the SP
register depending on whether EPT support is enabled. With EPT the SP is
reduced by 4 bytes (and the written value is 0-padded) but without EPT support
it is only reduced by 2 bytes. The difference can be observed when the CS.DB
field is 1 (32-bit) but not when it's 0 (16-bit).
The internal segment descriptor cache exist even in real/vm8096 mode. The CS.D
also should be respected instead of just default operand/address-size/66H
prefix/67H prefix during instruction decoding. This patch fixes it by also
adjusting operand/address-size according to CS.D.
Reported-by: Pedro Fonseca <pfonseca@cs.washington.edu>
Tested-by: Pedro Fonseca <pfonseca@cs.washington.edu>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Pedro Fonseca <pfonseca@cs.washington.edu>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Entering and exiting SMM may require ISA specific handling under certain
circumstances. This commit adds two new callbacks with empty implementations.
Actual functionality will be added in following commits.
* pre_enter_smm() is to be called when injecting an SMM, before any
SMM related vcpu state has been changed
* pre_leave_smm() is to be called when emulating the RSM instruction,
when the vcpu is in real mode and before any SMM related vcpu state
has been restored
Signed-off-by: Ladi Prosek <lprosek@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When compiling the kernel with the '-frecord-gcc-switches' flag, objtool
complains:
arch/x86/kvm/emulate.o: warning: objtool: .GCC.command.line+0x0: special: can't find new instruction
And also the kernel fails to link.
The problem is that the 'kvm_fastop_exception' code gets placed into the
throwaway '.GCC.command.line' section instead of '.text'.
Exception fixup code is conventionally placed in the '.fixup' section,
so put it there where it belongs.
Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Pull x86 fixes from Ingo Molnar:
"Another round of CR3/PCID related fixes (I think this addresses all
but one of the known problems with PCID support), an objtool fix plus
a Clang fix that (finally) solves all Clang quirks to build a bootable
x86 kernel as-is"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/asm: Fix inline asm call constraints for Clang
objtool: Handle another GCC stack pointer adjustment bug
x86/mm/32: Load a sane CR3 before cpu_init() on secondary CPUs
x86/mm/32: Move setup_clear_cpu_cap(X86_FEATURE_PCID) earlier
x86/mm/64: Stop using CR3.PCID == 0 in ASID-aware code
x86/mm: Factor out CR3-building code
For inline asm statements which have a CALL instruction, we list the
stack pointer as a constraint to convince GCC to ensure the frame
pointer is set up first:
static inline void foo()
{
register void *__sp asm(_ASM_SP);
asm("call bar" : "+r" (__sp))
}
Unfortunately, that pattern causes Clang to corrupt the stack pointer.
The fix is easy: convert the stack pointer register variable to a global
variable.
It should be noted that the end result is different based on the GCC
version. With GCC 6.4, this patch has exactly the same result as
before:
defconfig defconfig-nofp distro distro-nofp
before 9820389 9491555 8816046 8516940
after 9820389 9491555 8816046 8516940
With GCC 7.2, however, GCC's behavior has changed. It now changes its
behavior based on the conversion of the register variable to a global.
That somehow convinces it to *always* set up the frame pointer before
inserting *any* inline asm. (Therefore, listing the variable as an
output constraint is a no-op and is no longer necessary.) It's a bit
overkill, but the performance impact should be negligible. And in fact,
there's a nice improvement with frame pointers disabled:
defconfig defconfig-nofp distro distro-nofp
before 9796316 9468236 9076191 8790305
after 9796957 9464267 9076381 8785949
So in summary, while listing the stack pointer as an output constraint
is no longer necessary for newer versions of GCC, it's still needed for
older versions.
Suggested-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reported-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Miguel Bernal Marin <miguel.bernal.marin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/3db862e970c432ae823cf515c52b54fec8270e0e.1505942196.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Routine check_cr_write() will trigger emulator_get_cpuid()->
kvm_cpuid() to get maxphyaddr, and NULL is passed as values
for ebx/ecx/edx. This is problematic because kvm_cpuid() will
dereference these pointers.
Fixes: d1cd3ce900 ("KVM: MMU: check guest CR3 reserved bits based on its physical address width.")
Reported-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
This patch exposes 5 level page table feature to the VM.
At the same time, the canonical virtual address checking is
extended to support both 48-bits and 57-bits address width.
Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Currently, KVM uses CR3_L_MODE_RESERVED_BITS to check the
reserved bits in CR3. Yet the length of reserved bits in
guest CR3 should be based on the physical address width
exposed to the VM. This patch changes CR3 check logic to
calculate the reserved bits at runtime.
Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Return false in kvm_cpuid() when it fails to find the cpuid
entry. Also, this routine(and its caller) is optimized with
a new argument - check_limit, so that the check_cpuid_limit()
fall back can be avoided.
Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
- Better machine check handling for HV KVM
- Ability to support guests with threads=2, 4 or 8 on POWER9
- Fix for a race that could cause delayed recognition of signals
- Fix for a bug where POWER9 guests could sleep with interrupts pending.
ARM:
- VCPU request overhaul
- allow timer and PMU to have their interrupt number selected from userspace
- workaround for Cavium erratum 30115
- handling of memory poisonning
- the usual crop of fixes and cleanups
s390:
- initial machine check forwarding
- migration support for the CMMA page hinting information
- cleanups and fixes
x86:
- nested VMX bugfixes and improvements
- more reliable NMI window detection on AMD
- APIC timer optimizations
Generic:
- VCPU request overhaul + documentation of common code patterns
- kvm_stat improvements
There is a small conflict in arch/s390 due to an arch-wide field rename.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM updates from Paolo Bonzini:
"PPC:
- Better machine check handling for HV KVM
- Ability to support guests with threads=2, 4 or 8 on POWER9
- Fix for a race that could cause delayed recognition of signals
- Fix for a bug where POWER9 guests could sleep with interrupts pending.
ARM:
- VCPU request overhaul
- allow timer and PMU to have their interrupt number selected from userspace
- workaround for Cavium erratum 30115
- handling of memory poisonning
- the usual crop of fixes and cleanups
s390:
- initial machine check forwarding
- migration support for the CMMA page hinting information
- cleanups and fixes
x86:
- nested VMX bugfixes and improvements
- more reliable NMI window detection on AMD
- APIC timer optimizations
Generic:
- VCPU request overhaul + documentation of common code patterns
- kvm_stat improvements"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (124 commits)
Update my email address
kvm: vmx: allow host to access guest MSR_IA32_BNDCFGS
x86: kvm: mmu: use ept a/d in vmcs02 iff used in vmcs12
kvm: x86: mmu: allow A/D bits to be disabled in an mmu
x86: kvm: mmu: make spte mmio mask more explicit
x86: kvm: mmu: dead code thanks to access tracking
KVM: PPC: Book3S: Fix typo in XICS-on-XIVE state saving code
KVM: PPC: Book3S HV: Close race with testing for signals on guest entry
KVM: PPC: Book3S HV: Simplify dynamic micro-threading code
KVM: x86: remove ignored type attribute
KVM: LAPIC: Fix lapic timer injection delay
KVM: lapic: reorganize restart_apic_timer
KVM: lapic: reorganize start_hv_timer
kvm: nVMX: Check memory operand to INVVPID
KVM: s390: Inject machine check into the nested guest
KVM: s390: Inject machine check into the guest
tools/kvm_stat: add new interactive command 'b'
tools/kvm_stat: add new command line switch '-i'
tools/kvm_stat: fix error on interactive command 'g'
KVM: SVM: suppress unnecessary NMI singlestep on GIF=0 and nested exit
...
The macro insn_fetch marks the 'type' argument as having a specified
alignment. Type attributes can only be applied to structs, unions, or
enums, but insn_fetch is only ever invoked with integral types, so Clang
produces 19 -Wignored-attributes warnings for this source file.
Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
TF is handled a bit differently for syscall and sysret, compared
to the other instructions: TF is checked after the instruction completes,
so that the OS can disable #DB at a syscall by adding TF to FMASK.
When the sysret is executed the #DB is taken "as if" the syscall insn
just completed.
KVM emulates syscall so that it can trap 32-bit syscall on Intel processors.
Fix the behavior, otherwise you could get #DB on a user stack which is not
nice. This does not affect Linux guests, as they use an IST or task gate
for #DB.
This fixes CVE-2017-7518.
Cc: stable@vger.kernel.org
Reported-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
em_fxstor previously called fxstor_fixup. Both created instances of
struct fxregs_state on the stack, which triggered the warning:
arch/x86/kvm/emulate.c:4018:12: warning: stack frame size of 1080 bytes
in function
'em_fxrstor' [-Wframe-larger-than=]
static int em_fxrstor(struct x86_emulate_ctxt *ctxt)
^
with CONFIG_FRAME_WARN set to 1024.
This patch does the fixup in em_fxstor now, avoiding one additional
struct fxregs_state, and now fxstor_fixup can be removed as it has no
other call sites.
Further, the calculation for offsets into xmm_space can be shared
between em_fxstor and em_fxsave.
Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com>
[Clean up calculation of offsets and fix it for 64-bit mode. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
get_msr() of MSR_EFER is currently always going to succeed, but static
checker doesn't see that far.
Don't complicate stuff and just use 0 for the fallback -- it means that
the feature is not present.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
On AMD, the effect of set_nmi_mask called by emulate_iret_real and em_rsm
on hflags is reverted later on in x86_emulate_instruction where hflags are
overwritten with ctxt->emul_flags (the kvm_set_hflags call). This manifests
as a hang when rebooting Windows VMs with QEMU, OVMF, and >1 vcpu.
Instead of trying to merge ctxt->emul_flags into vcpu->arch.hflags after
an instruction is emulated, this commit deletes emul_flags altogether and
makes the emulator access vcpu->arch.hflags using two new accessors. This
way all changes, on the emulator side as well as in functions called from
the emulator and accessing vcpu state with emul_to_vcpu, are preserved.
More details on the bug and its manifestation with Windows and OVMF:
It's a KVM bug in the interaction between SMI/SMM and NMI, specific to AMD.
I believe that the SMM part explains why we started seeing this only with
OVMF.
KVM masks and unmasks NMI when entering and leaving SMM. When KVM emulates
the RSM instruction in em_rsm, the set_nmi_mask call doesn't stick because
later on in x86_emulate_instruction we overwrite arch.hflags with
ctxt->emul_flags, effectively reverting the effect of the set_nmi_mask call.
The AMD-specific hflag of interest here is HF_NMI_MASK.
When rebooting the system, Windows sends an NMI IPI to all but the current
cpu to shut them down. Only after all of them are parked in HLT will the
initiating cpu finish the restart. If NMI is masked, other cpus never get
the memo and the initiating cpu spins forever, waiting for
hal!HalpInterruptProcessorsStarted to drop. That's the symptom we observe.
Fixes: a584539b24 ("KVM: x86: pass the whole hflags field to emulator and back")
Signed-off-by: Ladi Prosek <lprosek@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Hardware support for faulting on the cpuid instruction is not required to
emulate it, because cpuid triggers a VM exit anyways. KVM handles the relevant
MSRs (MSR_PLATFORM_INFO and MSR_MISC_FEATURES_ENABLE) and upon a
cpuid-induced VM exit checks the cpuid faulting state and the CPL.
kvm_require_cpl is even kind enough to inject the GP fault for us.
Signed-off-by: Kyle Huey <khuey@kylehuey.com>
Reviewed-by: David Matlack <dmatlack@google.com>
[Return "1" from kvm_emulate_cpuid, it's not void. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This is CVE-2017-2583. On Intel this causes a failed vmentry because
SS's type is neither 3 nor 7 (even though the manual says this check is
only done for usable SS, and the dmesg splat says that SS is unusable!).
On AMD it's worse: svm.c is confused and sets CPL to 0 in the vmcb.
The fix fabricates a data segment descriptor when SS is set to a null
selector, so that CPL and SS.DPL are set correctly in the VMCS/vmcb.
Furthermore, only allow setting SS to a NULL selector if SS.RPL < 3;
this in turn ensures CPL < 3 because RPL must be equal to CPL.
Thanks to Andy Lutomirski and Willy Tarreau for help in analyzing
the bug and deciphering the manuals.
Reported-by: Xiaohan Zhang <zhangxiaohan1@huawei.com>
Fixes: 79d5b4c3cd
Cc: stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Introduces segemented_write_std.
Switches from emulated reads/writes to standard read/writes in fxsave,
fxrstor, sgdt, and sidt. This fixes CVE-2017-2584, a longstanding
kernel memory leak.
Since commit 283c95d0e3 ("KVM: x86: emulate FXSAVE and FXRSTOR",
2016-11-09), which is luckily not yet in any final release, this would
also be an exploitable kernel memory *write*!
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: stable@vger.kernel.org
Fixes: 96051572c8
Fixes: 283c95d0e3
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Steve Rutherford <srutherford@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When a guest causes a NPF which requires emulation, KVM sometimes walks
the guest page tables to translate the GVA to a GPA. This is unnecessary
most of the time on AMD hardware since the hardware provides the GPA in
EXITINFO2.
The only exception cases involve string operations involving rep or
operations that use two memory locations. With rep, the GPA will only be
the value of the initial NPF and with dual memory locations we won't know
which memory address was translated into EXITINFO2.
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
x86: userspace can now hide nested VMX features from guests; nested
VMX can now run Hyper-V in a guest; support for AVX512_4VNNIW and
AVX512_FMAPS in KVM; infrastructure support for virtual Intel GPUs.
PPC: support for KVM guests on POWER9; improved support for interrupt
polling; optimizations and cleanups.
s390: two small optimizations, more stuff is in flight and will be
in 4.11.
ARM: support for the GICv3 ITS on 32bit platforms.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM updates from Paolo Bonzini:
"Small release, the most interesting stuff is x86 nested virt
improvements.
x86:
- userspace can now hide nested VMX features from guests
- nested VMX can now run Hyper-V in a guest
- support for AVX512_4VNNIW and AVX512_FMAPS in KVM
- infrastructure support for virtual Intel GPUs.
PPC:
- support for KVM guests on POWER9
- improved support for interrupt polling
- optimizations and cleanups.
s390:
- two small optimizations, more stuff is in flight and will be in
4.11.
ARM:
- support for the GICv3 ITS on 32bit platforms"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (94 commits)
arm64: KVM: pmu: Reset PMSELR_EL0.SEL to a sane value before entering the guest
KVM: arm/arm64: timer: Check for properly initialized timer on init
KVM: arm/arm64: vgic-v2: Limit ITARGETSR bits to number of VCPUs
KVM: x86: Handle the kthread worker using the new API
KVM: nVMX: invvpid handling improvements
KVM: nVMX: check host CR3 on vmentry and vmexit
KVM: nVMX: introduce nested_vmx_load_cr3 and call it on vmentry
KVM: nVMX: propagate errors from prepare_vmcs02
KVM: nVMX: fix CR3 load if L2 uses PAE paging and EPT
KVM: nVMX: load GUEST_EFER after GUEST_CR0 during emulated VM-entry
KVM: nVMX: generate MSR_IA32_CR{0,4}_FIXED1 from guest CPUID
KVM: nVMX: fix checks on CR{0,4} during virtual VMX operation
KVM: nVMX: support restore of VMX capability MSRs
KVM: nVMX: generate non-true VMX MSRs based on true versions
KVM: x86: Do not clear RFLAGS.TF when a singlestep trap occurs.
KVM: x86: Add kvm_skip_emulated_instruction and use it.
KVM: VMX: Move skip_emulated_instruction out of nested_vmx_check_vmcs12
KVM: VMX: Reorder some skip_emulated_instruction calls
KVM: x86: Add a return value to kvm_emulate_cpuid
KVM: PPC: Book3S: Move prototypes for KVM functions into kvm_ppc.h
...
em_jmp_far and em_ret_far assumed that setting IP can only fail in 64
bit mode, but syzkaller proved otherwise (and SDM agrees).
Code segment was restored upon failure, but it was left uninitialized
outside of long mode, which could lead to a leak of host kernel stack.
We could have fixed that by always saving and restoring the CS, but we
take a simpler approach and just break any guest that manages to fail
as the error recovery is error-prone and modern CPUs don't need emulator
for this.
Found by syzkaller:
WARNING: CPU: 2 PID: 3668 at arch/x86/kvm/emulate.c:2217 em_ret_far+0x428/0x480
Kernel panic - not syncing: panic_on_warn set ...
CPU: 2 PID: 3668 Comm: syz-executor Not tainted 4.9.0-rc4+ #49
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
[...]
Call Trace:
[...] __dump_stack lib/dump_stack.c:15
[...] dump_stack+0xb3/0x118 lib/dump_stack.c:51
[...] panic+0x1b7/0x3a3 kernel/panic.c:179
[...] __warn+0x1c4/0x1e0 kernel/panic.c:542
[...] warn_slowpath_null+0x2c/0x40 kernel/panic.c:585
[...] em_ret_far+0x428/0x480 arch/x86/kvm/emulate.c:2217
[...] em_ret_far_imm+0x17/0x70 arch/x86/kvm/emulate.c:2227
[...] x86_emulate_insn+0x87a/0x3730 arch/x86/kvm/emulate.c:5294
[...] x86_emulate_instruction+0x520/0x1ba0 arch/x86/kvm/x86.c:5545
[...] emulate_instruction arch/x86/include/asm/kvm_host.h:1116
[...] complete_emulated_io arch/x86/kvm/x86.c:6870
[...] complete_emulated_mmio+0x4e9/0x710 arch/x86/kvm/x86.c:6934
[...] kvm_arch_vcpu_ioctl_run+0x3b7a/0x5a90 arch/x86/kvm/x86.c:6978
[...] kvm_vcpu_ioctl+0x61e/0xdd0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2557
[...] vfs_ioctl fs/ioctl.c:43
[...] do_vfs_ioctl+0x18c/0x1040 fs/ioctl.c:679
[...] SYSC_ioctl fs/ioctl.c:694
[...] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
[...] entry_SYSCALL_64_fastpath+0x1f/0xc2
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: stable@vger.kernel.org
Fixes: d1442d85cc ("KVM: x86: Handle errors when RIP is set during far jumps")
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Internal errors were reported on 16 bit fxsave and fxrstor with ipxe.
Old Intels don't have unrestricted_guest, so we have to emulate them.
The patch takes advantage of the hardware implementation.
AMD and Intel differ in saving and restoring other fields in first 32
bytes. A test wrote 0xff to the fxsave area, 0 to upper bits of MCSXR
in the fxsave area, executed fxrstor, rewrote the fxsave area to 0xee,
and executed fxsave:
Intel (Nehalem):
7f 1f 7f 7f ff 00 ff 07 ff ff ff ff ff ff 00 00
ff ff ff ff ff ff 00 00 ff ff 00 00 ff ff 00 00
Intel (Haswell -- deprecated FPU CS and FPU DS):
7f 1f 7f 7f ff 00 ff 07 ff ff ff ff 00 00 00 00
ff ff ff ff 00 00 00 00 ff ff 00 00 ff ff 00 00
AMD (Opteron 2300-series):
7f 1f 7f 7f ff 00 ee ee ee ee ee ee ee ee ee ee
ee ee ee ee ee ee ee ee ff ff 00 00 ff ff 02 00
fxsave/fxrstor will only be emulated on early Intels, so KVM can't do
much to improve the situation.
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Move the existing exception handling for inline assembly into a macro
and switch its return values to X86EMUL type.
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Alignments are exclusive, so 5 modes can be expressed in 3 bits.
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Commit 41061cdb98 ("KVM: emulate: do not initialize memopp") removes a
check for non-NULL under incorrect assumptions. An undefined instruction
with a ModR/M byte with Mod=0 and R/M-5 (e.g. 0xc7 0x15) will attempt
to dereference a null pointer here.
Fixes: 41061cdb98
Message-Id: <1477592752-126650-2-git-send-email-osh@google.com>
Signed-off-by: Owen Hofmann <osh@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sean Christopherson