Commit 4d2a1560 authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: nSVM: Use KVM-governed feature framework to track "vVM{SAVE,LOAD} enabled" 

Track "virtual VMSAVE/VMLOAD exposed to L1" via a governed feature flag
instead of using a dedicated bit/flag in vcpu_svm.

Opportunistically add a comment explaining why KVM disallows virtual
VMLOAD/VMSAVE when the vCPU model is Intel.

No functional change intended.

Link: https://lore.kernel.org/r/20230815203653.519297-11-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 4365a455

arch/x86/kvm/governed_features.h

+1 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ KVM_GOVERNED_X86_FEATURE(XSAVES) 
KVM_GOVERNED_X86_FEATURE(VMX)

KVM_GOVERNED_X86_FEATURE(NRIPS)

KVM_GOVERNED_X86_FEATURE(TSCRATEMSR)

KVM_GOVERNED_X86_FEATURE(V_VMSAVE_VMLOAD)



#undef KVM_GOVERNED_X86_FEATURE

#undef KVM_GOVERNED_FEATURE

arch/x86/kvm/svm/nested.c

+1 −1
Original line number Diff line number Diff line
@@ -107,7 +107,7 @@ static void nested_svm_uninit_mmu_context(struct kvm_vcpu *vcpu) 


static bool nested_vmcb_needs_vls_intercept(struct vcpu_svm *svm)

{

	if (!svm->v_vmload_vmsave_enabled)

	if (!guest_can_use(&svm->vcpu, X86_FEATURE_V_VMSAVE_VMLOAD))

		return true;



	if (!nested_npt_enabled(svm))

arch/x86/kvm/svm/svm.c

+7 −3
Original line number Diff line number Diff line
@@ -1194,8 +1194,6 @@ static inline void init_vmcb_after_set_cpuid(struct kvm_vcpu *vcpu) 


		set_msr_interception(vcpu, svm->msrpm, MSR_IA32_SYSENTER_EIP, 0, 0);

		set_msr_interception(vcpu, svm->msrpm, MSR_IA32_SYSENTER_ESP, 0, 0);



		svm->v_vmload_vmsave_enabled = false;

	} else {

		/*

		 * If hardware supports Virtual VMLOAD VMSAVE then enable it
@@ -4266,7 +4264,13 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) 


	svm->lbrv_enabled = lbrv && guest_cpuid_has(vcpu, X86_FEATURE_LBRV);



	svm->v_vmload_vmsave_enabled = vls && guest_cpuid_has(vcpu, X86_FEATURE_V_VMSAVE_VMLOAD);

	/*

	 * Intercept VMLOAD if the vCPU mode is Intel in order to emulate that

	 * VMLOAD drops bits 63:32 of SYSENTER (ignoring the fact that exposing

	 * SVM on Intel is bonkers and extremely unlikely to work).

	 */

	if (!guest_cpuid_is_intel(vcpu))

		kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_V_VMSAVE_VMLOAD);



	svm->pause_filter_enabled = kvm_cpu_cap_has(X86_FEATURE_PAUSEFILTER) &&

			guest_cpuid_has(vcpu, X86_FEATURE_PAUSEFILTER);

arch/x86/kvm/svm/svm.h

+0 −1
Original line number Diff line number Diff line
@@ -259,7 +259,6 @@ struct vcpu_svm { 
	bool soft_int_injected;



	/* optional nested SVM features that are enabled for this guest  */

	bool v_vmload_vmsave_enabled      : 1;

	bool lbrv_enabled                 : 1;

	bool pause_filter_enabled         : 1;

	bool pause_threshold_enabled      : 1;