Suppress code breakpoints if MOV/POP SS blocking is active and the guest
CPU is Intel, i.e. if the guest thinks it's running on an Intel CPU.
Intel CPUs inhibit code #DBs when MOV/POP SS blocking is active, whereas
AMD (and its descendents) do not.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/x86.c | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7403221c868e..013580c355d7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8542,6 +8542,23 @@ int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu)
}
EXPORT_SYMBOL_GPL(kvm_skip_emulated_instruction);
+static bool kvm_is_code_breakpoint_inhibited(struct kvm_vcpu *vcpu)
+{
+ u32 shadow;
+
+ if (kvm_get_rflags(vcpu) & X86_EFLAGS_RF)
+ return true;
+
+ /*
+ * Intel CPUs inhibit code #DBs when MOV/POP SS blocking is active,
+ * but AMD CPUs do not. MOV/POP SS blocking is rare, check that first
+ * to avoid the relatively expensive CPUID lookup.
+ */
+ shadow = static_call(kvm_x86_get_interrupt_shadow)(vcpu);
+ return (shadow & KVM_X86_SHADOW_INT_MOV_SS) &&
+ guest_cpuid_is_intel(vcpu);
+}
+
static bool kvm_vcpu_check_code_breakpoint(struct kvm_vcpu *vcpu,
int emulation_type, int *r)
{
@@ -8584,7 +8601,7 @@ static bool kvm_vcpu_check_code_breakpoint(struct kvm_vcpu *vcpu,
}
if (unlikely(vcpu->arch.dr7 & DR7_BP_EN_MASK) &&
- !(kvm_get_rflags(vcpu) & X86_EFLAGS_RF)) {
+ !kvm_is_code_breakpoint_inhibited(vcpu)) {
unsigned long eip = kvm_get_linear_rip(vcpu);
u32 dr6 = kvm_vcpu_check_hw_bp(eip, 0,
vcpu->arch.dr7,
--
2.37.2.672.g94769d06f0-goog
