From: "Radim Krčmář" <rkrcmar@redhat.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Alexander Graf <agraf@suse.de>,
"Michael S. Tsirkin" <mst@redhat.com>,
"Gabriel L. Somlo" <gsomlo@gmail.com>
Subject: [PATCH 2/4] KVM: x86: prevent MWAIT in guest with buggy MONITOR
Date: Wed, 3 May 2017 21:37:31 +0200 [thread overview]
Message-ID: <20170503193733.13409-3-rkrcmar@redhat.com> (raw)
In-Reply-To: <20170503193733.13409-1-rkrcmar@redhat.com>
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.
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 3ed7dd8737ab..63d5fb65ea30 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -231,6 +231,9 @@ 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
--
2.12.2
next prev parent reply other threads:[~2017-05-03 19:38 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-03 19:37 [PATCH 0/4] KVM: x86: kvm_mwait_in_guest() cleanup and fixes Radim Krčmář
2017-05-03 19:37 ` [PATCH 1/4] KVM: svm: prevent MWAIT in guest with erratum 400 Radim Krčmář
2017-05-03 20:11 ` Borislav Petkov
2017-05-04 14:02 ` Radim Krčmář
2017-05-04 16:45 ` Borislav Petkov
2017-05-03 19:37 ` Radim Krčmář [this message]
2017-05-03 19:37 ` [PATCH 3/4] KVM: x86: drop bogus MWAIT check Radim Krčmář
2017-05-04 10:58 ` Paolo Bonzini
2017-05-04 14:33 ` Radim Krčmář
2017-05-04 18:29 ` Michael S. Tsirkin
2017-05-04 20:03 ` Radim Krčmář
2017-05-04 18:26 ` Michael S. Tsirkin
2017-05-03 19:37 ` [PATCH 4/4] KVM: x86: simplify kvm_mwait_in_guest() Radim Krčmář
2017-05-03 19:45 ` [PATCH 0/4] KVM: x86: kvm_mwait_in_guest() cleanup and fixes Alexander Graf
2017-05-04 17:56 ` Gabriel L. Somlo
2017-05-04 18:07 ` Radim Krčmář
2017-05-05 13:02 ` Gabriel L. Somlo
2017-05-06 16:48 ` Gabriel L. Somlo
2017-05-08 7:23 ` Paolo Bonzini
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