On Wed, Aug 26, 2009 at 12:02 PM, Avi Kivity<avi@xxxxxxxxxx> wrote:
> On 08/25/2009 01:37 AM, Mohammed Gamal wrote:
>>
>> Return to userspace instead of repeatedly trying to emulate
>> instructions that have already failed
>>
>> Signed-off-by: Mohammed Gamal<m.gamal005@xxxxxxxxx>
>> ---
>> arch/x86/kvm/vmx.c | 6 +++++-
>> 1 files changed, 5 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index 6b57eed..c559bb7 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -3337,6 +3337,8 @@ static void handle_invalid_guest_state(struct
>> kvm_vcpu *vcpu)
>>
>> if (err != EMULATE_DONE) {
>> kvm_report_emulation_failure(vcpu, "emulation
>> failure");
>> + vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
>> + vcpu->run->internal.suberror =
>> KVM_INTERNAL_ERROR_EMULATION;
>> break;
>> }
>>
>> @@ -3607,7 +3609,9 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu)
>> vmx->entry_time = ktime_get();
>>
>> /* Handle invalid guest state instead of entering VMX */
>> - if (vmx->emulation_required&& emulate_invalid_guest_state) {
>> + if (vmx->emulation_required&& emulate_invalid_guest_state
>> + && !(vcpu->run->exit_reason == KVM_EXIT_INTERNAL_ERROR&&
>> + vcpu->run->internal.suberror ==
>> KVM_INTERNAL_ERROR_EMULATION)) {
>> handle_invalid_guest_state(vcpu);
>> return;
>> }
>>
>
> Still suffers from the same problem. You don't always update
> vcpu->run->exit_reason, so you can't test it. Best to return a value from
> handle_invalid_guest_state() (the standard return codes for exit handlers
> are 1 for return-to-guest, 0 for return-to-host, and -errno to return with
> an error).
>
I was thinking of the same idea since I was also concerned about
vcpu->run->exit_reason not being updated. But how can we interpret the
return values of handle_invalid_guest_state() inside vmx_vcpu_run()
since it doesn't have a return value. Or would it be better to move
handle_invalid_guest_state() to the standard vmx exit handlers?
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