KVM: x86: prevent MWAIT in guest with buggy MONITOR
"Linux Kernel Mailing List" <[email protected]> Sat, 10 Feb 2018 22:00:18 +0000 (UTC)
| Newsgroups | gmane.linux.kernel.commits.head |
|---|---|
| Message-ID | <[email protected]> |
Web: https://git.kernel.org/torvalds/c/2a140f3b6e23a309453b6f68709a50ece543f0f4 Commit: 2a140f3b6e23a309453b6f68709a50ece543f0f4 Parent: 0d37d26f11bc1c0085d0c89ba603e3bb2c7f7076 Refname: refs/heads/master Author: Radim Krčmář <[email protected]> AuthorDate: Wed Nov 29 22:23:41 2017 +0100 Committer: Paolo Bonzini <[email protected]> CommitDate: Thu Dec 14 09:26:42 2017 +0100 KVM: x86: prevent MWAIT in guest with buggy MONITOR 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 <[email protected]> Acked-by: Borislav Petkov <[email protected]> Acked-by: Michael S. Tsirkin <[email protected]> Signed-off-by: Radim Krčmář <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]> --- 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 -- To unsubscribe from this list: send the line "unsubscribe git-commits-head" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html