KVM: SVM: Fix reading of DR6
In contrast to VMX, SVM dose not automatically transfer DR6 into the
VCPU's arch.dr6. So if we face a DR6 read, we must consult a new vendor
hook to obtain the current value. And as SVM now picks the DR6 state
from its VMCB, we also need a set callback in order to write updates of
DR6 back.
Fixes a regression of 020df0794f.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 33fef07..fdf83af 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -700,6 +700,8 @@
void (*set_idt)(struct kvm_vcpu *vcpu, struct desc_ptr *dt);
void (*get_gdt)(struct kvm_vcpu *vcpu, struct desc_ptr *dt);
void (*set_gdt)(struct kvm_vcpu *vcpu, struct desc_ptr *dt);
+ u64 (*get_dr6)(struct kvm_vcpu *vcpu);
+ void (*set_dr6)(struct kvm_vcpu *vcpu, unsigned long value);
void (*set_dr7)(struct kvm_vcpu *vcpu, unsigned long value);
void (*cache_reg)(struct kvm_vcpu *vcpu, enum kvm_reg reg);
unsigned long (*get_rflags)(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index c7168a5..e81df8f 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1671,6 +1671,19 @@
mark_dirty(svm->vmcb, VMCB_ASID);
}
+static u64 svm_get_dr6(struct kvm_vcpu *vcpu)
+{
+ return to_svm(vcpu)->vmcb->save.dr6;
+}
+
+static void svm_set_dr6(struct kvm_vcpu *vcpu, unsigned long value)
+{
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ svm->vmcb->save.dr6 = value;
+ mark_dirty(svm->vmcb, VMCB_DR);
+}
+
static void svm_set_dr7(struct kvm_vcpu *vcpu, unsigned long value)
{
struct vcpu_svm *svm = to_svm(vcpu);
@@ -4286,6 +4299,8 @@
.set_idt = svm_set_idt,
.get_gdt = svm_get_gdt,
.set_gdt = svm_set_gdt,
+ .get_dr6 = svm_get_dr6,
+ .set_dr6 = svm_set_dr6,
.set_dr7 = svm_set_dr7,
.cache_reg = svm_cache_reg,
.get_rflags = svm_get_rflags,
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 7661eb1..79b360e 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5149,6 +5149,15 @@
return 1;
}
+static u64 vmx_get_dr6(struct kvm_vcpu *vcpu)
+{
+ return vcpu->arch.dr6;
+}
+
+static void vmx_set_dr6(struct kvm_vcpu *vcpu, unsigned long val)
+{
+}
+
static void vmx_set_dr7(struct kvm_vcpu *vcpu, unsigned long val)
{
vmcs_writel(GUEST_DR7, val);
@@ -8556,6 +8565,8 @@
.set_idt = vmx_set_idt,
.get_gdt = vmx_get_gdt,
.set_gdt = vmx_set_gdt,
+ .get_dr6 = vmx_get_dr6,
+ .set_dr6 = vmx_set_dr6,
.set_dr7 = vmx_set_dr7,
.cache_reg = vmx_cache_reg,
.get_rflags = vmx_get_rflags,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 59907c9..59b95b1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -722,6 +722,12 @@
}
EXPORT_SYMBOL_GPL(kvm_get_cr8);
+static void kvm_update_dr6(struct kvm_vcpu *vcpu)
+{
+ if (!(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP))
+ kvm_x86_ops->set_dr6(vcpu, vcpu->arch.dr6);
+}
+
static void kvm_update_dr7(struct kvm_vcpu *vcpu)
{
unsigned long dr7;
@@ -750,6 +756,7 @@
if (val & 0xffffffff00000000ULL)
return -1; /* #GP */
vcpu->arch.dr6 = (val & DR6_VOLATILE) | DR6_FIXED_1;
+ kvm_update_dr6(vcpu);
break;
case 5:
if (kvm_read_cr4_bits(vcpu, X86_CR4_DE))
@@ -791,7 +798,10 @@
return 1;
/* fall through */
case 6:
- *val = vcpu->arch.dr6;
+ if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)
+ *val = vcpu->arch.dr6;
+ else
+ *val = kvm_x86_ops->get_dr6(vcpu);
break;
case 5:
if (kvm_read_cr4_bits(vcpu, X86_CR4_DE))
@@ -2960,8 +2970,11 @@
static void kvm_vcpu_ioctl_x86_get_debugregs(struct kvm_vcpu *vcpu,
struct kvm_debugregs *dbgregs)
{
+ unsigned long val;
+
memcpy(dbgregs->db, vcpu->arch.db, sizeof(vcpu->arch.db));
- dbgregs->dr6 = vcpu->arch.dr6;
+ _kvm_get_dr(vcpu, 6, &val);
+ dbgregs->dr6 = val;
dbgregs->dr7 = vcpu->arch.dr7;
dbgregs->flags = 0;
memset(&dbgregs->reserved, 0, sizeof(dbgregs->reserved));
@@ -2975,6 +2988,7 @@
memcpy(vcpu->arch.db, dbgregs->db, sizeof(vcpu->arch.db));
vcpu->arch.dr6 = dbgregs->dr6;
+ kvm_update_dr6(vcpu);
vcpu->arch.dr7 = dbgregs->dr7;
kvm_update_dr7(vcpu);
@@ -6749,6 +6763,7 @@
memset(vcpu->arch.db, 0, sizeof(vcpu->arch.db));
vcpu->arch.dr6 = DR6_FIXED_1;
+ kvm_update_dr6(vcpu);
vcpu->arch.dr7 = DR7_FIXED_1;
kvm_update_dr7(vcpu);