Commit 88ab24ad authored by Joerg Roedel's avatar Joerg Roedel Committed by Avi Kivity
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KVM: SVM: Don't sync nested cr8 to lapic and back 



This patch makes syncing of the guest tpr to the lapic
conditional on !nested. Otherwise a nested guest using the
TPR could freeze the guest.
Another important change this patch introduces is that the
cr8 intercept bits are no longer ORed at vmrun emulation if
the guest sets VINTR_MASKING in its VMCB. The reason is that
nested cr8 accesses need alway be handled by the nested
hypervisor because they change the shadow version of the
tpr.

Cc: stable@kernel.org
Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 4c7da8cb

arch/x86/kvm/svm.c

+31 −15
Original line number Diff line number Diff line
@@ -1832,21 +1832,6 @@ static bool nested_svm_vmrun(struct vcpu_svm *svm) 
	svm->vmcb->save.dr6 = nested_vmcb->save.dr6;

	svm->vmcb->save.cpl = nested_vmcb->save.cpl;



	/* We don't want a nested guest to be more powerful than the guest,

	   so all intercepts are ORed */

	svm->vmcb->control.intercept_cr_read |=

		nested_vmcb->control.intercept_cr_read;

	svm->vmcb->control.intercept_cr_write |=

		nested_vmcb->control.intercept_cr_write;

	svm->vmcb->control.intercept_dr_read |=

		nested_vmcb->control.intercept_dr_read;

	svm->vmcb->control.intercept_dr_write |=

		nested_vmcb->control.intercept_dr_write;

	svm->vmcb->control.intercept_exceptions |=

		nested_vmcb->control.intercept_exceptions;



	svm->vmcb->control.intercept |= nested_vmcb->control.intercept;



	svm->nested.vmcb_msrpm = nested_vmcb->control.msrpm_base_pa;



	/* cache intercepts */
@@ -1864,6 +1849,28 @@ static bool nested_svm_vmrun(struct vcpu_svm *svm) 
	else

		svm->vcpu.arch.hflags &= ~HF_VINTR_MASK;



	if (svm->vcpu.arch.hflags & HF_VINTR_MASK) {

		/* We only want the cr8 intercept bits of the guest */

		svm->vmcb->control.intercept_cr_read &= ~INTERCEPT_CR8_MASK;

		svm->vmcb->control.intercept_cr_write &= ~INTERCEPT_CR8_MASK;

	}



	/* We don't want a nested guest to be more powerful than the guest,

	   so all intercepts are ORed */

	svm->vmcb->control.intercept_cr_read |=

		nested_vmcb->control.intercept_cr_read;

	svm->vmcb->control.intercept_cr_write |=

		nested_vmcb->control.intercept_cr_write;

	svm->vmcb->control.intercept_dr_read |=

		nested_vmcb->control.intercept_dr_read;

	svm->vmcb->control.intercept_dr_write |=

		nested_vmcb->control.intercept_dr_write;

	svm->vmcb->control.intercept_exceptions |=

		nested_vmcb->control.intercept_exceptions;



	svm->vmcb->control.intercept |= nested_vmcb->control.intercept;



	svm->vmcb->control.lbr_ctl = nested_vmcb->control.lbr_ctl;

	svm->vmcb->control.int_vector = nested_vmcb->control.int_vector;

	svm->vmcb->control.int_state = nested_vmcb->control.int_state;

	svm->vmcb->control.tsc_offset += nested_vmcb->control.tsc_offset;
@@ -2526,6 +2533,9 @@ static void update_cr8_intercept(struct kvm_vcpu *vcpu, int tpr, int irr) 
{

	struct vcpu_svm *svm = to_svm(vcpu);



	if (is_nested(svm) && (vcpu->arch.hflags & HF_VINTR_MASK))

		return;



	if (irr == -1)

		return;
@@ -2629,6 +2639,9 @@ static inline void sync_cr8_to_lapic(struct kvm_vcpu *vcpu) 
{

	struct vcpu_svm *svm = to_svm(vcpu);



	if (is_nested(svm) && (vcpu->arch.hflags & HF_VINTR_MASK))

		return;



	if (!(svm->vmcb->control.intercept_cr_write & INTERCEPT_CR8_MASK)) {

		int cr8 = svm->vmcb->control.int_ctl & V_TPR_MASK;

		kvm_set_cr8(vcpu, cr8);
@@ -2640,6 +2653,9 @@ static inline void sync_lapic_to_cr8(struct kvm_vcpu *vcpu) 
	struct vcpu_svm *svm = to_svm(vcpu);

	u64 cr8;



	if (is_nested(svm) && (vcpu->arch.hflags & HF_VINTR_MASK))

		return;



	cr8 = kvm_get_cr8(vcpu);

	svm->vmcb->control.int_ctl &= ~V_TPR_MASK;

	svm->vmcb->control.int_ctl |= cr8 & V_TPR_MASK;

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