Re: [Xen-devel] [PATCH v4 5/6] xen/x86: add PHYSDEVOP_msi_set_enable

[Marek Marczykowski <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

On Thu, Feb 28, 2019 at 03:58:37AM -0700, Jan Beulich wrote:
> >>> On 27.02.19 at 16:05, <marmarek@xxxxxxxxxxxxxxxxxxxxxx> wrote:
> > On Wed, Feb 27, 2019 at 04:41:37AM -0700, Jan Beulich wrote:
> >> >>> On 07.02.19 at 01:07, <marmarek@xxxxxxxxxxxxxxxxxxxxxx> wrote:
> >> > +int msi_msix_set_enable(struct pci_dev *pdev, int mode, int enable)
> >> > +{
> >> > +    int ret;
> >> > +
> >> > +    ret = xsm_msi_set_enable(XSM_DM_PRIV, pdev->domain,
> >> > +                             (pdev->seg << 16) | (pdev->bus << 8) | 
> >> > pdev->devfn,
> >> > +                             mode, enable);
> >> > +    if ( ret )
> >> > +        return ret;
> >> > +
> >> > +    switch ( mode )
> >> > +    {
> >> > +    case PHYSDEVOP_MSI_SET_ENABLE_MSI:
> >> > +        msi_set_enable(pdev, enable);
> >> > +        break;
> >> > +
> >> > +    case PHYSDEVOP_MSI_SET_ENABLE_MSIX:
> >> > +        msix_set_enable(pdev, enable);
> >> > +        break;
> >> > +    }
> >> 
> >> What about a call to pci_intx()? 
> > 
> > Should pci_intx(dev, !enable) be called in all those cases?
> 
> Well, that depends whether Dom0 is involved, which is where the
> operation would normally be done. But since this is about bypassing
> pciback, I think it may be needed.

Shouldn't that be done by device model itself? Or even on command from
the target domain? Automatically toggling INTx when manipulating MSI(-X)
seems wrong.

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

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