Messages in this thread Patch in this message | | | From | Radim Krčmář <> | Subject | [PATCH v2 1/3] KVM: x86: prevent MWAIT in guest with buggy MONITOR | Date | Wed, 29 Nov 2017 22:23:41 +0100 |
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The bug prevents MWAIT from waking up after a write to the monitored cache line. KVM might emulate a CPU model that shouldn't have the bug, so the guest would not employ a workaround and possibly miss wakeups. Better to avoid the situation.
Reviewed-by: Alexander Graf <agraf@suse.de> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> --- arch/x86/kvm/x86.h | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index d0b95b7a90b4..81f5f50794f6 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -281,6 +281,9 @@ static inline bool kvm_mwait_in_guest(void) return false; } + if (boot_cpu_has_bug(X86_BUG_MONITOR)) + return false; + /* * Intel CPUs without CPUID5_ECX_INTERRUPT_BREAK are problematic as * they would allow guest to stop the CPU completely by disabling -- 2.14.2
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