KVM: x86: make double/triple fault promotion generic to all exceptions

Move Double-Fault generation logic out of page fault
exception generating function to cover more generic case.

Signed-off-by: Eddie Dong <eddie.dong@intel.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 61 insertions, 28 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a1e1bc9d412d..8d860e0301a0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -257,12 +257,68 @@ 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)
+{
+        switch (vector) {
+        case PF_VECTOR:
+                return EXCPT_PF;
+        case DE_VECTOR:
+        case TS_VECTOR:
+        case NP_VECTOR:
+        case SS_VECTOR:
+        case GP_VECTOR:
+                return EXCPT_CONTRIBUTORY;
+        default:
+                break;
+        }
+        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) {
+        queue:
+                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;
+        if (prev_nr == DF_VECTOR) {
+                /* triple fault -> shutdown */
+                set_bit(KVM_REQ_TRIPLE_FAULT, &vcpu->requests);
+                return;
+        }
+        class1 = exception_class(prev_nr);
+        class2 = exception_class(nr);
+        if ((class1 == EXCPT_CONTRIBUTORY && class2 == EXCPT_CONTRIBUTORY)
+                || (class1 == EXCPT_PF && class2 != EXCPT_BENIGN)) {
+                /* generate double fault per SDM Table 5-5 */
+                vcpu->arch.exception.pending = true;
+                vcpu->arch.exception.has_error_code = true;
+                vcpu->arch.exception.nr = DF_VECTOR;
+                vcpu->arch.exception.error_code = 0;
+        } else
+                /* replace previous exception with a new one in a hope
+                   that instruction re-execution will regenerate lost
+                   exception */
+                goto queue;
+}
+
 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);
 
@@ -270,25 +326,6 @@ void kvm_inject_page_fault(struct kvm_vcpu *vcpu, unsigned long addr,
                            u32 error_code)
 {
         ++vcpu->stat.pf_guest;
-
-        if (vcpu->arch.exception.pending) {
-                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;
-                }
-        }
         vcpu->arch.cr2 = addr;
         kvm_queue_exception_e(vcpu, PF_VECTOR, error_code);
 }
@@ -301,11 +338,7 @@ 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);