From 8d4846b9b15045598d760470789716fb08b9b317 Mon Sep 17 00:00:00 2001
From: Tom Lendacky <thomas.lendacky@amd.com>
Date: Thu, 10 Dec 2020 11:09:43 -0600
Subject: [PATCH] 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: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <8db966fa2f9803d6454ce773863025d0e2e7f3cc.1607620209.git.thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/svm/svm.c | 9 +++++++++
arch/x86/kvm/svm/svm.h | 37 +++++++++++++++++++++++--------------
arch/x86/kvm/x86.c | 3 +++
3 files changed, 35 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index db81fb131033d..bec427acab208 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -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);
}
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index f96a0a66ca35d..abfe53d6b3dc8 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -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);
}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9685d056d8089..d88e334b19e76 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -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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