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authorSean Christopherson <seanjc@google.com>2022-08-30 23:15:52 +0000
committerPaolo Bonzini <pbonzini@redhat.com>2022-09-26 12:03:05 -0400
commitbaf67ca8e545b6ac77a7e2abd52b9961e672f8f0 (patch)
tree90e9fd3920e5c27534055718b24812ed53915244
parentd500e1ed3dc873818277e109ccf6407118669236 (diff)
downloadlinux-baf67ca8e545b6ac77a7e2abd52b9961e672f8f0.tar.bz2
KVM: x86: Suppress code #DBs on Intel if MOV/POP SS blocking is active
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@google.com> Link: https://lore.kernel.org/r/20220830231614.3580124-6-seanjc@google.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rw-r--r--arch/x86/kvm/x86.c19
1 files changed, 18 insertions, 1 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a7ae08e68582..ee22264ab471 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8554,6 +8554,23 @@ 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)
{
@@ -8596,7 +8613,7 @@ 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,