Commit b5170063 authored by Wanpeng Li's avatar Wanpeng Li Committed by Paolo Bonzini
Browse files

KVM: X86: Provide a capability to disable cstate msr read intercepts 



Allow guest reads CORE cstate when exposing host CPU power management capabilities
to the guest. PKG cstate is restricted to avoid a guest to get the whole package
information in multi-tenant scenario.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Liran Alon <liran.alon@oracle.com>
Signed-off-by: default avatarWanpeng Li <wanpengli@tencent.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 8ffdaa7f

Documentation/virtual/kvm/api.txt

+1 −0
Original line number Diff line number Diff line
@@ -4894,6 +4894,7 @@ Valid bits in args[0] are 
#define KVM_X86_DISABLE_EXITS_MWAIT            (1 << 0)

#define KVM_X86_DISABLE_EXITS_HLT              (1 << 1)

#define KVM_X86_DISABLE_EXITS_PAUSE            (1 << 2)

#define KVM_X86_DISABLE_EXITS_CSTATE           (1 << 3)



Enabling this capability on a VM provides userspace with a way to no

longer intercept some instructions for improved latency in some

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -882,6 +882,7 @@ struct kvm_arch { 
	bool mwait_in_guest;

	bool hlt_in_guest;

	bool pause_in_guest;

	bool cstate_in_guest;



	unsigned long irq_sources_bitmap;

	s64 kvmclock_offset;

arch/x86/kvm/vmx/vmx.c

+6 −0
Original line number Diff line number Diff line
@@ -6637,6 +6637,12 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id) 
	vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_SYSENTER_CS, MSR_TYPE_RW);

	vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_SYSENTER_ESP, MSR_TYPE_RW);

	vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_SYSENTER_EIP, MSR_TYPE_RW);

	if (kvm_cstate_in_guest(kvm)) {

		vmx_disable_intercept_for_msr(msr_bitmap, MSR_CORE_C1_RES, MSR_TYPE_R);

		vmx_disable_intercept_for_msr(msr_bitmap, MSR_CORE_C3_RESIDENCY, MSR_TYPE_R);

		vmx_disable_intercept_for_msr(msr_bitmap, MSR_CORE_C6_RESIDENCY, MSR_TYPE_R);

		vmx_disable_intercept_for_msr(msr_bitmap, MSR_CORE_C7_RESIDENCY, MSR_TYPE_R);

	}

	vmx->msr_bitmap_mode = 0;



	vmx->loaded_vmcs = &vmx->vmcs01;

arch/x86/kvm/x86.c

+4 −1
Original line number Diff line number Diff line
@@ -3098,7 +3098,8 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) 
		r = KVM_CLOCK_TSC_STABLE;

		break;

	case KVM_CAP_X86_DISABLE_EXITS:

		r |=  KVM_X86_DISABLE_EXITS_HLT | KVM_X86_DISABLE_EXITS_PAUSE;

		r |=  KVM_X86_DISABLE_EXITS_HLT | KVM_X86_DISABLE_EXITS_PAUSE |

		      KVM_X86_DISABLE_EXITS_CSTATE;

		if(kvm_can_mwait_in_guest())

			r |= KVM_X86_DISABLE_EXITS_MWAIT;

		break;
@@ -4615,6 +4616,8 @@ split_irqchip_unlock: 
			kvm->arch.hlt_in_guest = true;

		if (cap->args[0] & KVM_X86_DISABLE_EXITS_PAUSE)

			kvm->arch.pause_in_guest = true;

		if (cap->args[0] & KVM_X86_DISABLE_EXITS_CSTATE)

			kvm->arch.cstate_in_guest = true;

		r = 0;

		break;

	case KVM_CAP_MSR_PLATFORM_INFO:

arch/x86/kvm/x86.h

+5 −0
Original line number Diff line number Diff line
@@ -333,6 +333,11 @@ static inline bool kvm_pause_in_guest(struct kvm *kvm) 
	return kvm->arch.pause_in_guest;

}



static inline bool kvm_cstate_in_guest(struct kvm *kvm)

{

	return kvm->arch.cstate_in_guest;

}



DECLARE_PER_CPU(struct kvm_vcpu *, current_vcpu);



static inline void kvm_before_interrupt(struct kvm_vcpu *vcpu)

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