Re: [PATCH] xen/vpci: do not use pci_sanitize_bar_memory for domU

[Jan Beulich <jbeulich@xxxxxxxx>]

On 25.02.2026 00:12, Ariadne Conill wrote:
> From: Steven Noonan <steven@xxxxxxxxx>
> 
> This function should only be used for the hardware domain, because it
> compares addresses against the host e820 map.

The same is true for its sibling function, pci_check_bar(). For both the
question is whether skipping is the right thing, or whether for DomU-s
checking against their memory map is what is needed instead.

> --- a/xen/drivers/vpci/header.c
> +++ b/xen/drivers/vpci/header.c
> @@ -394,13 +394,15 @@ static int modify_bars(const struct pci_dev *pdev, 
> uint16_t cmd, bool rom_only)
>              }
>          }
>  
> -        rc = pci_sanitize_bar_memory(bar->mem);
> -        if ( rc )
> -        {
> -            gprintk(XENLOG_WARNING,
> -                    "%pp: failed to sanitize BAR#%u memory: %d\n",
> -                    &pdev->sbdf, i, rc);
> -            return rc;
> +        if (is_hardware_domain(pdev->domain)) {

Nit: Style (see surrounding code you alter).

> +            rc = pci_sanitize_bar_memory(mem);
> +            if ( rc )
> +            {
> +                gprintk(XENLOG_WARNING,
> +                        "%pp: failed to sanitize BAR#%u memory: %d\n",
> +                        &pdev->sbdf, i, rc);
> +                return rc;
> +            }

To avoid the need for re-indentation here (reducing churn) you may want
to leverage that rc is 0 ahead of the call to pci_sanitize_bar_memory().
I.e. you could make just the call conditional, without touching anything
else.

Jan