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KVM: SVM: Prevent debugging under SEV-ES

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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: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <8db966fa2f9803d6454ce773863025d0e2e7f3cc.1607620209.git.thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Tom Lendacky 2020-12-10 11:09:43 -06:00 committed by Paolo Bonzini
parent f1c6366e30
commit 8d4846b9b1
3 changed files with 35 additions and 14 deletions
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9
arch/x86/kvm/svm/svm.c
View File

@ -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);
}

37
arch/x86/kvm/svm/svm.h
View File

@ -272,21 +272,24 @@ static inline void set_dr_intercepts(struct vcpu_svm *svm)
{
struct vmcb *vmcb = get_host_vmcb(svm);
vmcb_set_intercept(&vmcb->control, INTERCEPT_DR0_READ);
vmcb_set_intercept(&vmcb->control, INTERCEPT_DR1_READ);
vmcb_set_intercept(&vmcb->control, INTERCEPT_DR2_READ);
vmcb_set_intercept(&vmcb->control, INTERCEPT_DR3_READ);
vmcb_set_intercept(&vmcb->control, INTERCEPT_DR4_READ);
vmcb_set_intercept(&vmcb->control, INTERCEPT_DR5_READ);
vmcb_set_intercept(&vmcb->control, INTERCEPT_DR6_READ);
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);
vmcb_set_intercept(&vmcb->control, INTERCEPT_DR3_READ);
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_DR0_WRITE);
vmcb_set_intercept(&vmcb->control, INTERCEPT_DR1_WRITE);
vmcb_set_intercept(&vmcb->control, INTERCEPT_DR2_WRITE);
vmcb_set_intercept(&vmcb->control, INTERCEPT_DR3_WRITE);
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_DR0_WRITE);
vmcb_set_intercept(&vmcb->control, INTERCEPT_DR1_WRITE);
vmcb_set_intercept(&vmcb->control, INTERCEPT_DR2_WRITE);
vmcb_set_intercept(&vmcb->control, INTERCEPT_DR3_WRITE);
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_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);
}

3
arch/x86/kvm/x86.c
View File

@ -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)) {