Commit 8d4846b9 authored by Tom Lendacky's avatar Tom Lendacky Committed by Paolo Bonzini
Browse files

KVM: SVM: Prevent debugging under SEV-ES 



Since the guest register state of an SEV-ES guest is encrypted, debugging
is not supported. Update the code to prevent guest debugging when the
guest has protected state.

Additionally, an SEV-ES guest must only and always intercept DR7 reads and
writes. Update set_dr_intercepts() and clr_dr_intercepts() to account for
this.

Signed-off-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Message-Id: <8db966fa2f9803d6454ce773863025d0e2e7f3cc.1607620209.git.thomas.lendacky@amd.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent f1c6366e

arch/x86/kvm/svm/svm.c

+9 −0
Original line number Diff line number Diff line
@@ -1805,6 +1805,9 @@ static void svm_set_dr6(struct vcpu_svm *svm, unsigned long value) 
{

	struct vmcb *vmcb = svm->vmcb;



	if (svm->vcpu.arch.guest_state_protected)

		return;



	if (unlikely(value != vmcb->save.dr6)) {

		vmcb->save.dr6 = value;

		vmcb_mark_dirty(vmcb, VMCB_DR);
@@ -1815,6 +1818,9 @@ static void svm_sync_dirty_debug_regs(struct kvm_vcpu *vcpu) 
{

	struct vcpu_svm *svm = to_svm(vcpu);



	if (vcpu->arch.guest_state_protected)

		return;



	get_debugreg(vcpu->arch.db[0], 0);

	get_debugreg(vcpu->arch.db[1], 1);

	get_debugreg(vcpu->arch.db[2], 2);
@@ -1833,6 +1839,9 @@ static void svm_set_dr7(struct kvm_vcpu *vcpu, unsigned long value) 
{

	struct vcpu_svm *svm = to_svm(vcpu);



	if (vcpu->arch.guest_state_protected)

		return;



	svm->vmcb->save.dr7 = value;

	vmcb_mark_dirty(svm->vmcb, VMCB_DR);

}

arch/x86/kvm/svm/svm.h

+23 −14
Original line number Diff line number Diff line
@@ -272,6 +272,7 @@ static inline void set_dr_intercepts(struct vcpu_svm *svm) 
{

	struct vmcb *vmcb = get_host_vmcb(svm);



	if (!sev_es_guest(svm->vcpu.kvm)) {

		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR0_READ);

		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR1_READ);

		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR2_READ);
@@ -279,7 +280,6 @@ static inline void set_dr_intercepts(struct vcpu_svm *svm) 
		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR4_READ);

		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR5_READ);

		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR6_READ);

	vmcb_set_intercept(&vmcb->control, INTERCEPT_DR7_READ);

		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR0_WRITE);

		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR1_WRITE);

		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR2_WRITE);
@@ -287,6 +287,9 @@ static inline void set_dr_intercepts(struct vcpu_svm *svm) 
		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR4_WRITE);

		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR5_WRITE);

		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR6_WRITE);

	}



	vmcb_set_intercept(&vmcb->control, INTERCEPT_DR7_READ);

	vmcb_set_intercept(&vmcb->control, INTERCEPT_DR7_WRITE);



	recalc_intercepts(svm);
@@ -298,6 +301,12 @@ static inline void clr_dr_intercepts(struct vcpu_svm *svm) 


	vmcb->control.intercepts[INTERCEPT_DR] = 0;



	/* DR7 access must remain intercepted for an SEV-ES guest */

	if (sev_es_guest(svm->vcpu.kvm)) {

		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR7_READ);

		vmcb_set_intercept(&vmcb->control, INTERCEPT_DR7_WRITE);

	}



	recalc_intercepts(svm);

}

arch/x86/kvm/x86.c

+3 −0
Original line number Diff line number Diff line
@@ -9664,6 +9664,9 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, 
	unsigned long rflags;

	int i, r;



	if (vcpu->arch.guest_state_protected)

		return -EINVAL;



	vcpu_load(vcpu);



	if (dbg->control & (KVM_GUESTDBG_INJECT_DB | KVM_GUESTDBG_INJECT_BP)) {

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