Re: [PATCH 19/24] KVM: x86 emulator: fix in/out emulation.

[Avi Kivity <avi@redhat.com>]

On 03/09/2010 04:09 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.
>
>
> index def4877..315e8a8 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -1488,29 +1488,9 @@ static int shutdown_interception(struct vcpu_svm *svm)
>
>   static int io_interception(struct vcpu_svm *svm)
>   {
> -	u32 io_info = svm->vmcb->control.exit_info_1; /* address size bug? */
> -	int size, in, string;
> -	unsigned port;
> -
>   	++svm->vcpu.stat.io_exits;
>
> -	svm->next_rip = svm->vmcb->control.exit_info_2;
> -
> -	string = (io_info&  SVM_IOIO_STR_MASK) != 0;
> -
> -	if (string) {
> -		if (emulate_instruction(&svm->vcpu,
> -					0, 0, 0) == EMULATE_DO_MMIO)
> -			return 0;
> -		return 1;
> -	}
> -
> -	in = (io_info&  SVM_IOIO_TYPE_MASK) != 0;
> -	port = io_info>>  16;
> -	size = (io_info&  SVM_IOIO_SIZE_MASK)>>  SVM_IOIO_SIZE_SHIFT;
> -
> -	skip_emulated_instruction(&svm->vcpu);
> -	return kvm_emulate_pio(&svm->vcpu, in, size, port);
> +	return !(emulate_instruction(&svm->vcpu, 0, 0, 0) == EMULATE_DO_MMIO);
>   }
>    

We don't want to enter the emulator for non-string in/out.  Leftover 
test code?

>
>   static int nmi_interception(struct vcpu_svm *svm)
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index ae3217d..7f33d8e 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -2974,26 +2974,9 @@ static int handle_triple_fault(struct kvm_vcpu *vcpu)
>
>   static int handle_io(struct kvm_vcpu *vcpu)
>   {
> -	unsigned long exit_qualification;
> -	int size, in, string;
> -	unsigned port;
> -
>   	++vcpu->stat.io_exits;
> -	exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
> -	string = (exit_qualification&  16) != 0;
>
> -	if (string) {
> -		if (emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DO_MMIO)
> -			return 0;
> -		return 1;
> -	}
> -
> -	size = (exit_qualification&  7) + 1;
> -	in = (exit_qualification&  8) != 0;
> -	port = exit_qualification>>  16;
> -
> -	skip_emulated_instruction(vcpu);
> -	return kvm_emulate_pio(vcpu, in, size, port);
> +	return !(emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DO_MMIO);
>   }
>    

Ditto.


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