Re: [PATCH v4 RFC 2/6] x86/MSI-X: track host and guest mask‑all requests separately

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 22/06/15 15:47, Jan Beulich wrote:
> Host uses of the bits will be added subsequently, and must not be
> overridden by guests (including Dom0, namely when acting on behalf of
> a guest).
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
>
> --- a/xen/arch/x86/msi.c
> +++ b/xen/arch/x86/msi.c
> @@ -846,6 +846,12 @@ static int msix_capability_init(struct p
>  
>      if ( !msix->used_entries )
>      {
> +        msix->host_maskall = 0;
> +        if ( !msix->guest_maskall )
> +            control &= ~PCI_MSIX_FLAGS_MASKALL;
> +        else
> +            control |= PCI_MSIX_FLAGS_MASKALL;

Is the guest (or hardware) in a position to influence guest_maskall at
this point?  I am not sure that it is.

~Andrew