On Thu, Nov 12, 2009 at 01:41:31PM +0100, Jan Kiszka wrote:
> Gleb Natapov wrote:
> > On Wed, Nov 11, 2009 at 05:29:47PM -0200, Marcelo Tosatti wrote:
> >> I suppose a complete fix would be to follow the "Conditions for
> >> Generating a Double Fault" with support for handling exceptions
> >> serially.
> >>
> >> But this works for me.
> >>
> > I prefer proper solution. Like one attached (this is combination of ths
> > patch by Eddie Dong and my fix):
>
> Nice, preferred here as well. I only have a minor comment below.
>
Move Double-Fault generation logic out of page fault
exception generating function to cover more generic case.
Signed-off-by: Eddie Dong <eddie.dong@xxxxxxxxx>
Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 76c8375..88c4490 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -248,12 +248,61 @@ 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 == DE_VECTOR || (vector >= TS_VECTOR && vector <= GP_VECTOR))
+ 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) {
+ 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);
@@ -261,25 +310,6 @@ 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);
}
@@ -292,11 +322,7 @@ 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);
--
Gleb.
--
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