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>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 7d7b0d6..631f9b7 100644 (file)
--- 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.
                 */