On 05/23/2012 05:08 PM, Gleb Natapov wrote:
> "rep ins" emulation is going through emulator now. This is slow because
> emulator knows how to write back only one datum at a time. This patch
> provides fast path for the instruction in certain conditions. The
> conditions are: DF flag is not set, destination memory is RAM and single
> datum does not cross page boundary. If fast path code fails it falls
> back to emulation.
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index f75af40..20e3fb0 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -1887,21 +1887,31 @@ static int io_interception(struct vcpu_svm *svm)
> {
> struct kvm_vcpu *vcpu = &svm->vcpu;
> u32 io_info = svm->vmcb->control.exit_info_1; /* address size bug? */
> - int size, in, string;
> + int size, in, string, rep;
> unsigned port;
>
> ++svm->vcpu.stat.io_exits;
> string = (io_info & SVM_IOIO_STR_MASK) != 0;
> + rep = (io_info & SVM_IOIO_REP_MASK) != 0;
> in = (io_info & SVM_IOIO_TYPE_MASK) != 0;
> - if (string || in)
> - return emulate_instruction(vcpu, 0) == EMULATE_DONE;
>
If decode assists are not available, we still need to emulate, see 15.33.5.
> port = io_info >> 16;
> size = (io_info & SVM_IOIO_SIZE_MASK) >> SVM_IOIO_SIZE_SHIFT;
> svm->next_rip = svm->vmcb->control.exit_info_2;
> - skip_emulated_instruction(&svm->vcpu);
>
> - return kvm_fast_pio_out(vcpu, size, port);
> + if (!string && !in) {
> + skip_emulated_instruction(&svm->vcpu);
> + return kvm_fast_pio_out(vcpu, size, port);
> + } else if (string && in && rep) {
> + int addr_size = (io_info & SVM_IOIO_ASIZE_MASK) >>
> + SVM_IOIO_ASIZE_SHIFT;
> + int r = kvm_fast_string_pio_in(vcpu, size, port,
> + ffs(addr_size) - 1);
> + if (r != EMULATE_FAIL)
> + return r == EMULATE_DONE;
> + }
> +
> + return emulate_instruction(vcpu, 0) == EMULATE_DONE;
> }
>
--
error compiling committee.c: too many arguments to function
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
