Re: [PATCH v2 25/30] KVM: x86 emulator: fix in/out emulation.

[Avi Kivity <avi@redhat.com>]

On 03/14/2010 06:21 PM, Gleb Natapov wrote:
> in/out emulation is broken now. The breakage is different depending
> on where IO device resides. If it is in userspace emulator reports
> emulation failure since it incorrectly interprets kvm_emulate_pio()
> return value. If IO device is in the kernel emulation of 'in' will do
> nothing since kvm_emulate_pio() stores result directly into vcpu
> registers, so emulator will overwrite result of emulation during
> commit of shadowed register.
>
>
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index 8f5e4c8..344e17b 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -210,13 +210,13 @@ static u32 opcode_table[256] = {
>   	0, 0, 0, 0, 0, 0, 0, 0,
>   	/* 0xE0 - 0xE7 */
>   	0, 0, 0, 0,
> -	ByteOp | SrcImmUByte, SrcImmUByte,
> -	ByteOp | SrcImmUByte, SrcImmUByte,
> +	ByteOp | SrcImmUByte | DstAcc, SrcImmUByte | DstAcc,
> +	ByteOp | SrcImmUByte | DstAcc, SrcImmUByte | DstAcc,
>    

REX prefix shouldn't expand DstAcc to 64 bits here.  Might cause 
problems further down in the pipeline.+
>   	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);
>    

whitespace damage.

> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 3c5ffa2..37c6178 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3351,6 +3351,86 @@ emul_write:
>   	return emulator_write_emulated(addr, new, bytes, vcpu);
>   }
>
> +static int kernel_pio(struct kvm_vcpu *vcpu, void *pd)
> +{
> +	/* TODO: String I/O for in kernel device */
>    

ISTR this is actually needed for something.  Is this a regression?


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