Implement generic double fault generation mechanism

[Dong, Eddie]

    Move Double-Fault generation logic out of page fault
    exception generating function to cover more generic case.
    
    Signed-off-by: Eddie Dong <eddie.d...@intel.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ab1fdac..51a8dad 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -162,12 +162,59 @@ void kvm_set_apic_base(struct kvm_vcpu *vcpu, u64 data)
 }
 EXPORT_SYMBOL_GPL(kvm_set_apic_base);
 
+#define EXCPT_BENIGN           0
+#define EXCPT_CONTRIBUTORY     1
+#define EXCPT_PF               2
+
+static int exception_class(int vector)
+{
+       if (vector == 14)
+               return EXCPT_PF;
+       else if (vector == 0 || (vector >= 10 && vector <= 13))
+               return EXCPT_CONTRIBUTORY;
+       else
+               return EXCPT_BENIGN;
+}
+
+static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
+               unsigned nr, bool has_error, u32 error_code)
+{
+       u32 prev_nr;
+       int class1, class2;
+
+       if (!vcpu->arch.exception.pending) {
+               vcpu->arch.exception.pending = true;
+               vcpu->arch.exception.has_error_code = has_error;
+               vcpu->arch.exception.nr = nr;
+               vcpu->arch.exception.error_code = error_code;
+               return;
+       }
+
+       /* to check exception */
+       prev_nr = vcpu->arch.exception.nr;
+       class2 = exception_class(nr);
+       class1 = exception_class(prev_nr);
+       if ((class1 == EXCPT_CONTRIBUTORY && class2 == EXCPT_CONTRIBUTORY)
+               || (class1 == EXCPT_PF && class2 != EXCPT_BENIGN)) {
+               /* generate double fault per SDM Table 5-5 */
+               printk(KERN_DEBUG "kvm: double fault 0x%x on 0x%x\n",
+                       prev_nr, nr);
+               vcpu->arch.exception.pending = true;
+               vcpu->arch.exception.has_error_code = 1;
+               vcpu->arch.exception.nr = DF_VECTOR;
+               vcpu->arch.exception.error_code = 0;
+               if (prev_nr == DF_VECTOR) {
+                       /* triple fault -> shutdown */
+                       set_bit(KVM_REQ_TRIPLE_FAULT, &vcpu->requests);
+               }
+       } else
+               printk(KERN_ERR "Exception 0x%x on 0x%x happens serially\n",
+                       prev_nr, nr);
+}
+
 void kvm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr)
 {
-       WARN_ON(vcpu->arch.exception.pending);
-       vcpu->arch.exception.pending = true;
-       vcpu->arch.exception.has_error_code = false;
-       vcpu->arch.exception.nr = nr;
+       kvm_multiple_exception(vcpu, nr, false, 0);
 }
 EXPORT_SYMBOL_GPL(kvm_queue_exception);
 
@@ -176,18 +223,6 @@ 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) {
-                       /* triple fault -> shutdown */
-                       set_bit(KVM_REQ_TRIPLE_FAULT, &vcpu->requests);
-               }
-               return;
-       }
        vcpu->arch.cr2 = addr;
        kvm_queue_exception_e(vcpu, PF_VECTOR, error_code);
 }
@@ -200,11 +235,7 @@ EXPORT_SYMBOL_GPL(kvm_inject_nmi);
 
 void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code)
 {
-       WARN_ON(vcpu->arch.exception.pending);
-       vcpu->arch.exception.pending = true;
-       vcpu->arch.exception.has_error_code = true;
-       vcpu->arch.exception.nr = nr;
-       vcpu->arch.exception.error_code = error_code;
+       kvm_multiple_exception(vcpu, nr, true, error_code);
 }
 EXPORT_SYMBOL_GPL(kvm_queue_exception_e);
 

irq3.patch
Description: irq3.patch