KVM: VMX: Fix handling of a fault during NMI unblocked due to IRET

Bit 12 is undefined in any of the following cases:
 If the VM exit sets the valid bit in the IDT-vectoring information field.
 If the VM exit is due to a double fault.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 11 insertions, 6 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 7d7b0d6e3f58..631f9b720971 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3272,36 +3272,41 @@ static void update_tpr_threshold(struct kvm_vcpu *vcpu)
 static void vmx_complete_interrupts(struct vcpu_vmx *vmx)
 {
         u32 exit_intr_info;
-        u32 idt_vectoring_info;
+        u32 idt_vectoring_info = vmx->idt_vectoring_info;
         bool unblock_nmi;
         u8 vector;
         int type;
         bool idtv_info_valid;
         u32 error;
 
+        idtv_info_valid = idt_vectoring_info & VECTORING_INFO_VALID_MASK;
         exit_intr_info = vmcs_read32(VM_EXIT_INTR_INFO);
         if (cpu_has_virtual_nmis()) {
                 unblock_nmi = (exit_intr_info & INTR_INFO_UNBLOCK_NMI) != 0;
                 vector = exit_intr_info & INTR_INFO_VECTOR_MASK;
                 /*
-                 * SDM 3: 25.7.1.2
+                 * SDM 3: 27.7.1.2 (September 2008)
                  * Re-set bit "block by NMI" before VM entry if vmexit caused by
                  * a guest IRET fault.
+                 * SDM 3: 23.2.2 (September 2008)
+                 * Bit 12 is undefined in any of the following cases:
+                 *  If the VM exit sets the valid bit in the IDT-vectoring
+                 *   information field.
+                 *  If the VM exit is due to a double fault.
                  */
-                if (unblock_nmi && vector != DF_VECTOR)
+                if ((exit_intr_info & INTR_INFO_VALID_MASK) && unblock_nmi &&
+                    vector != DF_VECTOR && !idtv_info_valid)
                         vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO,
                                       GUEST_INTR_STATE_NMI);
         } else if (unlikely(vmx->soft_vnmi_blocked))
                 vmx->vnmi_blocked_time +=
                         ktime_to_ns(ktime_sub(ktime_get(), vmx->entry_time));
 
-        idt_vectoring_info = vmx->idt_vectoring_info;
-        idtv_info_valid = idt_vectoring_info & VECTORING_INFO_VALID_MASK;
         vector = idt_vectoring_info & VECTORING_INFO_VECTOR_MASK;
         type = idt_vectoring_info & VECTORING_INFO_TYPE_MASK;
         if (vmx->vcpu.arch.nmi_injected) {
                 /*
-                 * SDM 3: 25.7.1.2
+                 * SDM 3: 27.7.1.2 (September 2008)
                  * Clear bit "block by NMI" before VM entry if a NMI delivery
                  * faulted.
                  */