Re: [PATCH RFC v2] vPCI: account for hidden devices

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Wed, May 24, 2023 at 03:45:58PM +0200, Jan Beulich wrote:
> --- a/xen/drivers/vpci/header.c
> +++ b/xen/drivers/vpci/header.c
> @@ -218,6 +218,7 @@ static int modify_bars(const struct pci_
>      struct vpci_header *header = &pdev->vpci->header;
>      struct rangeset *mem = rangeset_new(NULL, NULL, 0);
>      struct pci_dev *tmp, *dev = NULL;
> +    const struct domain *d;
>      const struct vpci_msix *msix = pdev->vpci->msix;
>      unsigned int i;
>      int rc;
> @@ -285,9 +286,11 @@ static int modify_bars(const struct pci_
>  
>      /*
>       * Check for overlaps with other BARs. Note that only BARs that are
> -     * currently mapped (enabled) are checked for overlaps.
> +     * currently mapped (enabled) are checked for overlaps. Note also that
> +     * for Dom0 we also need to include hidden, i.e. DomXEN's, devices.
>       */
> -    for_each_pdev ( pdev->domain, tmp )
> +for ( d = pdev->domain; ; d = dom_xen ) {//todo

Looking at this again, I think this is slightly more complex, as during
runtime dom0 will get here with pdev->domain == hardware_domain OR
dom_xen, and hence you also need to account that devices that have
pdev->domain == dom_xen need to iterate over devices that belong to
the hardware_domain, ie:

for ( d = pdev->domain; ;
      d = (pdev->domain == dom_xen) ? hardware_domain : dom_xen )

And we likely want to limit this to devices that belong to the
hardware_domain or to dom_xen (in preparation for vPCI being used for
domUs).

Thanks, Roger.