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| author | Wanpeng Li <wanpengli@tencent.com> | 2018-03-12 04:53:02 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2018-03-16 22:03:51 +0100 |
| commit | 4d5422cea3b61f158d58924cbb43feada456ba5c (patch) | |
| tree | 0657ac655c54892dd6498d8e20b89380255d592a /arch/x86/kvm/x86.c | |
| parent | 4956aa3b8b59e336b77f1df0ac7ce1a94c0265f2 (diff) | |
| download | linux-next-4d5422cea3b61f158d58924cbb43feada456ba5c.tar.gz | |
KVM: X86: Provide a capability to disable MWAIT intercepts
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>
Diffstat (limited to 'arch/x86/kvm/x86.c')
| -rw-r--r-- | arch/x86/kvm/x86.c | 24 |
1 files changed, 20 insertions, 4 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 9e1496cb2345..db95d4d6f57b 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2813,9 +2813,15 @@ out: return r; } +static inline bool kvm_can_mwait_in_guest(void) +{ + return boot_cpu_has(X86_FEATURE_MWAIT) && + !boot_cpu_has_bug(X86_BUG_MONITOR); +} + int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) { - int r; + int r = 0; switch (ext) { case KVM_CAP_IRQCHIP: @@ -2871,8 +2877,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_ADJUST_CLOCK: r = KVM_CLOCK_TSC_STABLE; break; - case KVM_CAP_X86_GUEST_MWAIT: - r = kvm_mwait_in_guest(); + case KVM_CAP_X86_DISABLE_EXITS: + if(kvm_can_mwait_in_guest()) + r |= KVM_X86_DISABLE_EXITS_MWAIT; break; case KVM_CAP_X86_SMM: /* SMBASE is usually relocated above 1M on modern chipsets, @@ -2913,7 +2920,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) r = KVM_X2APIC_API_VALID_FLAGS; break; default: - r = 0; break; } return r; @@ -4218,6 +4224,16 @@ split_irqchip_unlock: r = 0; break; + case KVM_CAP_X86_DISABLE_EXITS: + r = -EINVAL; + if (cap->args[0] & ~KVM_X86_DISABLE_VALID_EXITS) + break; + + if ((cap->args[0] & KVM_X86_DISABLE_EXITS_MWAIT) && + kvm_can_mwait_in_guest()) + kvm->arch.mwait_in_guest = true; + r = 0; + break; default: r = -EINVAL; break; |