On Fri, Apr 29, 2022 at 03:05:32PM +0200, Jan Beulich wrote:
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> IOMMU code mapping / unmapping devices and interrupts will misbehave if
> a wrong command line option declared a function "phantom" when there's a
> real device at that position. Warn about this and adjust the specified
> stride (in the worst case ignoring the option altogether).
>
> Requested-by: Andrew Cooper <andrew.coop...@citrix.com>
> Signed-off-by: Jan Beulich <jbeul...@suse.com>
Reviewed-by: Roger Pau Monné <roger....@citrix.com>
FWIW, I would be fine with just discarding the stride option if one of
the phantom devices happen to report vendor/device IDs on the config
space.
> --- a/xen/drivers/passthrough/pci.c
> +++ b/xen/drivers/passthrough/pci.c
> @@ -451,7 +451,24 @@ static struct pci_dev *alloc_pdev(struct
> phantom_devs[i].slot == PCI_SLOT(devfn) &&
> phantom_devs[i].stride > PCI_FUNC(devfn) )
> {
> - pdev->phantom_stride = phantom_devs[i].stride;
> + pci_sbdf_t sbdf = pdev->sbdf;
> + unsigned int stride = phantom_devs[i].stride;
> +
> + while ( (sbdf.fn += stride) > PCI_FUNC(devfn) )
> + {
> + if ( pci_conf_read16(sbdf, PCI_VENDOR_ID) ==
> 0xffff &&
> + pci_conf_read16(sbdf, PCI_DEVICE_ID) ==
> 0xffff )
> + continue;
> + stride <<= 1;
> + printk(XENLOG_WARNING
> + "%pp looks to be a real device; bumping
> %04x:%02x:%02x stride to %u\n",
> + &sbdf, phantom_devs[i].seg,
> + phantom_devs[i].bus, phantom_devs[i].slot,
Can't you use pdev->sbdf here?
Thanks, Roger.
