Re: [PATCH v10 2/4] vpci/rebar: Free Rebar resources when init_rebar() fails

[Jan Beulich <jbeulich@xxxxxxxx>]

On 05.08.2025 05:49, Jiqian Chen wrote:
> --- a/xen/drivers/vpci/rebar.c
> +++ b/xen/drivers/vpci/rebar.c
> @@ -49,6 +49,32 @@ static void cf_check rebar_ctrl_write(const struct pci_dev 
> *pdev,
>      bar->guest_addr = bar->addr;
>  }
>  
> +static int cf_check cleanup_rebar(const struct pci_dev *pdev)
> +{
> +    int rc;
> +    uint32_t ctrl;
> +    unsigned int nbars;
> +    unsigned int rebar_offset = pci_find_ext_capability(pdev->sbdf,
> +                                                        
> PCI_EXT_CAP_ID_REBAR);
> +
> +    if ( !rebar_offset || !is_hardware_domain(pdev->domain) )
> +    {
> +        ASSERT_UNREACHABLE();
> +        return 0;
> +    }
> +
> +    ctrl = pci_conf_read32(pdev->sbdf, rebar_offset + PCI_REBAR_CTRL(0));
> +    nbars = MASK_EXTR(ctrl, PCI_REBAR_CTRL_NBAR_MASK);
> +
> +    rc = vpci_remove_registers(pdev->vpci, rebar_offset + PCI_REBAR_CAP(0),
> +                               PCI_REBAR_CTRL(nbars - 1));
> +    if ( rc )
> +        printk(XENLOG_ERR "%pd %pp: fail to remove Rebar handlers rc=%d\n",
> +               pdev->domain, &pdev->sbdf, rc);

MSI and MSI-X (now) have ASSERT_UNREACHABLE() on their respective paths. Is
there a reason this shouldn't be done here as well?

MSI and MSI-X further have another add-register below here, to ensure the
control register cannot be written. Again - is there a reason the same
shouldn't be done here? (If so, I think this may want putting in a comment.)

Jan