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 == 0 || (vector >= 10 && vector <= 13))
xx_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);
>
Jan
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