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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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9
arch/x86/kvm/vmx.c
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@@ -3746,13 +3746,11 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
CPU_BASED_UNCOND_IO_EXITING |
CPU_BASED_MOV_DR_EXITING |
CPU_BASED_USE_TSC_OFFSETING |
CPU_BASED_MWAIT_EXITING |
CPU_BASED_MONITOR_EXITING |
CPU_BASED_INVLPG_EXITING |
CPU_BASED_RDPMC_EXITING;
if (!kvm_mwait_in_guest())
min |= CPU_BASED_MWAIT_EXITING |
CPU_BASED_MONITOR_EXITING;
opt = CPU_BASED_TPR_SHADOW |
CPU_BASED_USE_MSR_BITMAPS |
CPU_BASED_ACTIVATE_SECONDARY_CONTROLS;
@@ -5544,6 +5542,9 @@ static u32 vmx_exec_control(struct vcpu_vmx *vmx)
exec_control |= CPU_BASED_CR3_STORE_EXITING |
CPU_BASED_CR3_LOAD_EXITING |
CPU_BASED_INVLPG_EXITING;
if (kvm_mwait_in_guest(vmx->vcpu.kvm))
exec_control &= ~(CPU_BASED_MWAIT_EXITING |
CPU_BASED_MONITOR_EXITING);
return exec_control;
}