KVM: Replace pending exception by PF if it happens serially

Replace previous exception with a new one in a hope that instruction
re-execution will regenerate lost exception.

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

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 30492f0..a066876 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -181,16 +181,22 @@ void kvm_inject_page_fault(struct kvm_vcpu *vcpu, unsigned long addr,
        ++vcpu->stat.pf_guest;
 
        if (vcpu->arch.exception.pending) {
-               if (vcpu->arch.exception.nr == PF_VECTOR) {
-                       printk(KERN_DEBUG "kvm: inject_page_fault:"
-                                       " double fault 0x%lx\n", addr);
-                       vcpu->arch.exception.nr = DF_VECTOR;
-                       vcpu->arch.exception.error_code = 0;
-               } else if (vcpu->arch.exception.nr == DF_VECTOR) {
+               switch(vcpu->arch.exception.nr) {
+               case DF_VECTOR:
                        /* triple fault -> shutdown */
                        set_bit(KVM_REQ_TRIPLE_FAULT, &vcpu->requests);
+                       return;
+               case PF_VECTOR:
+                       vcpu->arch.exception.nr = DF_VECTOR;
+                       vcpu->arch.exception.error_code = 0;
+                       return;
+               default:
+                       /* replace previous exception with a new one in a hope
+                          that instruction re-execution will regenerate lost
+                          exception */
+                       vcpu->arch.exception.pending = false;
+                       break;
                }
-               return;
        }
        vcpu->arch.cr2 = addr;
        kvm_queue_exception_e(vcpu, PF_VECTOR, error_code);