Commit e183d17a authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: nSVM: Use KVM-governed feature framework to track "LBRv enabled" 

Track "LBR virtualization exposed to L1" via a governed feature flag
instead of using a dedicated bit/flag in vcpu_svm.

Note, checking KVM's capabilities instead of the "lbrv" param means that
the code isn't strictly equivalent, as lbrv_enabled could have been set
if nested=false where as that the governed feature cannot.  But that's a
glorified nop as the feature/flag is consumed only by paths that are
gated by nSVM being enabled.

Link: https://lore.kernel.org/r/20230815203653.519297-12-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 4d2a1560

arch/x86/kvm/governed_features.h

+1 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ KVM_GOVERNED_X86_FEATURE(VMX) 
KVM_GOVERNED_X86_FEATURE(NRIPS)

KVM_GOVERNED_X86_FEATURE(TSCRATEMSR)

KVM_GOVERNED_X86_FEATURE(V_VMSAVE_VMLOAD)

KVM_GOVERNED_X86_FEATURE(LBRV)



#undef KVM_GOVERNED_X86_FEATURE

#undef KVM_GOVERNED_FEATURE

arch/x86/kvm/svm/nested.c

+13 −10
Original line number Diff line number Diff line
@@ -552,6 +552,7 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12 
	bool new_vmcb12 = false;

	struct vmcb *vmcb01 = svm->vmcb01.ptr;

	struct vmcb *vmcb02 = svm->nested.vmcb02.ptr;

	struct kvm_vcpu *vcpu = &svm->vcpu;



	nested_vmcb02_compute_g_pat(svm);
@@ -577,18 +578,18 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12 
		vmcb_mark_dirty(vmcb02, VMCB_DT);

	}



	kvm_set_rflags(&svm->vcpu, vmcb12->save.rflags | X86_EFLAGS_FIXED);

	kvm_set_rflags(vcpu, vmcb12->save.rflags | X86_EFLAGS_FIXED);



	svm_set_efer(&svm->vcpu, svm->nested.save.efer);

	svm_set_efer(vcpu, svm->nested.save.efer);



	svm_set_cr0(&svm->vcpu, svm->nested.save.cr0);

	svm_set_cr4(&svm->vcpu, svm->nested.save.cr4);

	svm_set_cr0(vcpu, svm->nested.save.cr0);

	svm_set_cr4(vcpu, svm->nested.save.cr4);



	svm->vcpu.arch.cr2 = vmcb12->save.cr2;



	kvm_rax_write(&svm->vcpu, vmcb12->save.rax);

	kvm_rsp_write(&svm->vcpu, vmcb12->save.rsp);

	kvm_rip_write(&svm->vcpu, vmcb12->save.rip);

	kvm_rax_write(vcpu, vmcb12->save.rax);

	kvm_rsp_write(vcpu, vmcb12->save.rsp);

	kvm_rip_write(vcpu, vmcb12->save.rip);



	/* In case we don't even reach vcpu_run, the fields are not updated */

	vmcb02->save.rax = vmcb12->save.rax;
@@ -602,7 +603,8 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12 
		vmcb_mark_dirty(vmcb02, VMCB_DR);

	}



	if (unlikely(svm->lbrv_enabled && (svm->nested.ctl.virt_ext & LBR_CTL_ENABLE_MASK))) {

	if (unlikely(guest_can_use(vcpu, X86_FEATURE_LBRV) &&

		     (svm->nested.ctl.virt_ext & LBR_CTL_ENABLE_MASK))) {

		/*

		 * Reserved bits of DEBUGCTL are ignored.  Be consistent with

		 * svm_set_msr's definition of reserved bits.
@@ -734,7 +736,7 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm, 


	vmcb02->control.virt_ext            = vmcb01->control.virt_ext &

					      LBR_CTL_ENABLE_MASK;

	if (svm->lbrv_enabled)

	if (guest_can_use(vcpu, X86_FEATURE_LBRV))

		vmcb02->control.virt_ext  |=

			(svm->nested.ctl.virt_ext & LBR_CTL_ENABLE_MASK);
@@ -1065,7 +1067,8 @@ int nested_svm_vmexit(struct vcpu_svm *svm) 
	if (!nested_exit_on_intr(svm))

		kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);



	if (unlikely(svm->lbrv_enabled && (svm->nested.ctl.virt_ext & LBR_CTL_ENABLE_MASK))) {

	if (unlikely(guest_can_use(vcpu, X86_FEATURE_LBRV) &&

		     (svm->nested.ctl.virt_ext & LBR_CTL_ENABLE_MASK))) {

		svm_copy_lbrs(vmcb12, vmcb02);

		svm_update_lbrv(vcpu);

	} else if (unlikely(vmcb01->control.virt_ext & LBR_CTL_ENABLE_MASK)) {

arch/x86/kvm/svm/svm.c

+2 −3
Original line number Diff line number Diff line
@@ -1024,7 +1024,7 @@ void svm_update_lbrv(struct kvm_vcpu *vcpu) 
	bool current_enable_lbrv = !!(svm->vmcb->control.virt_ext &

				      LBR_CTL_ENABLE_MASK);



	if (unlikely(is_guest_mode(vcpu) && svm->lbrv_enabled))

	if (unlikely(is_guest_mode(vcpu) && guest_can_use(vcpu, X86_FEATURE_LBRV)))

		if (unlikely(svm->nested.ctl.virt_ext & LBR_CTL_ENABLE_MASK))

			enable_lbrv = true;
@@ -4261,8 +4261,7 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) 


	kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_NRIPS);

	kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_TSCRATEMSR);



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

	kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_LBRV);



	/*

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

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 lbrv_enabled                 : 1;

	bool pause_filter_enabled         : 1;

	bool pause_threshold_enabled      : 1;

	bool vgif_enabled                 : 1;