Per volume 2 of the SDM, bits 63:15 and 12:4 of the exit qualification
field for debug exceptions are reserved (cleared to 0).
There is still an issue with stale DR6 bits potentially being
misreported for the current debug exception. DR6 should not have been
modified before vectoring the #DB exception, and the "new DR6 bits"
should be available somewhere, but it was and they aren't.
Fixes: b96fb439774e1 ("KVM: nVMX: fixes to nested virt interrupt injection")
Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/vmx.c | 3 ++-
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 8e90488c3d56..234f7320ba59 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -177,6 +177,7 @@ enum {
#define DR6_BD (1 << 13)
#define DR6_BS (1 << 14)
+#define DR6_BT (1 << 15)
#define DR6_RTM (1 << 16)
#define DR6_FIXED_1 0xfffe0ff0
#define DR6_INIT 0xffff0ff0
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 533a327372c8..01f729830fd9 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3293,7 +3293,8 @@ static int nested_vmx_check_exception(struct kvm_vcpu *vcpu, unsigned long *exit
} else {
if (vmcs12->exception_bitmap & (1u << nr)) {
if (nr == DB_VECTOR)
- *exit_qual = vcpu->arch.dr6;
+ *exit_qual = vcpu->arch.dr6 &
+ ~(DR6_FIXED_1 | DR6_BT | DR6_RTM);
else
*exit_qual = 0;
return 1;
--
2.19.0.444.g18242da7ef-goog
