Re: [Xen-devel] [PATCH v3 01/10] ioreq: terminate cf8 handling at hypervisor level

[Jan Beulich <jbeulich@xxxxxxxx>]

On 30.09.2019 15:32, Roger Pau Monne wrote:
> --- a/xen/arch/x86/hvm/ioreq.c
> +++ b/xen/arch/x86/hvm/ioreq.c
> @@ -1518,11 +1518,15 @@ static int hvm_access_cf8(
>  {
>      struct domain *d = current->domain;
>  
> -    if ( dir == IOREQ_WRITE && bytes == 4 )
> +    if ( bytes != 4 )
> +        return X86EMUL_OKAY;

I think it was already on v1 that Andrew had pointed out that e.g.
a 1-bye access to CF9 should still be forwarded. I guess you mean
to use X86EMUL_UNHANDLEABLE here, just like was done ...

> +    if ( dir == IOREQ_WRITE )
>          d->arch.hvm.pci_cf8 = *val;
> +    else
> +        *val = d->arch.hvm.pci_cf8;
>  
> -    /* We always need to fall through to the catch all emulator */
> -    return X86EMUL_UNHANDLEABLE;
> +    return X86EMUL_OKAY;
>  }

... universally before. The comment (suitably adjusted) may then
also want to move up.

Jan

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