Similar to the code in kvm_vcpu_check_singlestep, check for TF and,
depending on the origin, synthesize a DB exception or an exit to userspace.
Signed-off-by: Kyle Huey <khuey@xxxxxxxxxxxx>
---
arch/x86/kvm/vmx.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f404aef..6583e97 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2470,16 +2470,37 @@ static void skip_emulated_instruction_no_trap(struct kvm_vcpu *vcpu)
/* skipping an emulated instruction also counts */
vmx_set_interrupt_shadow(vcpu, 0);
}
static int skip_emulated_instruction(struct kvm_vcpu *vcpu)
{
skip_emulated_instruction_no_trap(vcpu);
+
+ if (unlikely(vmx_get_rflags(vcpu) & X86_EFLAGS_TF)) {
+ if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) {
+ vcpu->run->debug.arch.dr6 = DR6_BS | DR6_FIXED_1 |
+ DR6_RTM;
+ vcpu->run->debug.arch.pc = vcpu->arch.singlestep_rip;
+ vcpu->run->debug.arch.exception = DB_VECTOR;
+ vcpu->run->exit_reason = KVM_EXIT_DEBUG;
+ return 0;
+ }
+
+ /*
+ * "Certain debug exceptions may clear bit 0-3. The
+ * remaining contents of the DR6 register are never
+ * cleared by the processor".
+ */
+ vcpu->arch.dr6 &= ~15;
+ vcpu->arch.dr6 |= DR6_BS | DR6_RTM;
+ kvm_queue_exception(vcpu, DB_VECTOR);
+ }
+
return 1;
}
/*
* KVM wants to inject page-faults which it got to the guest. This function
* checks whether in a nested guest, we need to inject them to L1 or L2.
*/
static int nested_vmx_check_exception(struct kvm_vcpu *vcpu, unsigned nr)
--
2.10.2
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