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KVM: X86: Provide a capability to disable MWAIT intercepts

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Allowing a guest to execute MWAIT without interception enables a guest
to put a (physical) CPU into a power saving state, where it takes
longer to return from than what may be desired by the host.

Don't give a guest that power over a host by default. (Especially,
since nothing prevents a guest from using MWAIT even when it is not
advertised via CPUID.)

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Jan H. Schönherr <jschoenh@amazon.de>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Wanpeng Li
2018-03-12 04:53:02 -07:00
committed by Paolo Bonzini
parent 4956aa3b8b
commit 4d5422cea3
8 changed files with 53 additions and 25 deletions
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10
arch/x86/kvm/x86.h
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@@ -2,8 +2,6 @@
#ifndef ARCH_X86_KVM_X86_H
#define ARCH_X86_KVM_X86_H
#include <asm/processor.h>
#include <asm/mwait.h>
#include <linux/kvm_host.h>
#include <asm/pvclock.h>
#include "kvm_cache_regs.h"
@@ -266,10 +264,12 @@ static inline u64 nsec_to_cycles(struct kvm_vcpu *vcpu, u64 nsec)
__rem; \
})
static inline bool kvm_mwait_in_guest(void)
#define KVM_X86_DISABLE_EXITS_MWAIT (1 << 0)
#define KVM_X86_DISABLE_VALID_EXITS (KVM_X86_DISABLE_EXITS_MWAIT)
static inline bool kvm_mwait_in_guest(struct kvm *kvm)
{
return boot_cpu_has(X86_FEATURE_MWAIT) &&
!boot_cpu_has_bug(X86_BUG_MONITOR);
return kvm->arch.mwait_in_guest;
}
#endif