Re: [PATCH 2/2] x86: Bail out on unemulated instructions

[Gleb Natapov <gleb@redhat.com>]

On Sat, Aug 14, 2010 at 06:51:34PM +0300, Mohammed Gamal wrote:
> If emulation fails due to the instruction being unemulated. Return immediately
> instead of restarting the instruction and infinitely trying to execute it.
> 
This is already handled correctly as far as I can see. Sometimes
instruction should be retried and reexecute_instruction() checks
for that case. If instruction emulation fails in big real mode
re-executing instruction will be useless though, so what should be done
is to make reexecute_instruction() return false if vcpu is in big real
mode and cpu relies on emulation to handle it.
 
> Signed-off-by: Mohammed Gamal <m.gamal005@gmail.com>
> ---
>  arch/x86/kvm/x86.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 416aa0e..a31db44 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -4036,6 +4036,9 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
>  		}
>  
>  		++vcpu->stat.insn_emulation;
> +		if (r == X86EMUL_UNHANDLEABLE)
> +			return handle_emulation_failure(vcpu);
> +
>  		if (r)  {
>  			if (reexecute_instruction(vcpu, cr2))
>  				return EMULATE_DONE;
> @@ -4057,6 +4060,9 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
>  restart:
>  	r = x86_emulate_insn(&vcpu->arch.emulate_ctxt);
>  
> +	if (r == X86EMUL_UNHANDLEABLE)
> +		return handle_emulation_failure(vcpu);
> +
>  	if (r) { /* emulation failed */
>  		if (reexecute_instruction(vcpu, cr2))
>  			return EMULATE_DONE;
> -- 
> 1.7.0.4
> 
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

--
			Gleb.