Re: [PATCH] VMX: Return to userspace on invalid state emulation failure

[Avi Kivity <avi@redhat.com>]

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@gmail.com>
> ---
>   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).


-- 
error compiling committee.c: too many arguments to function