Re: [PATCH v10 4/4] vpci/msix: Free MSIX resources when init_msix() fails

[Jan Beulich <jbeulich@xxxxxxxx>]

On 05.08.2025 05:49, Jiqian Chen wrote:
> --- a/xen/drivers/vpci/msix.c
> +++ b/xen/drivers/vpci/msix.c
> @@ -655,6 +655,48 @@ int vpci_make_msix_hole(const struct pci_dev *pdev)
>      return 0;
>  }
>  
> +static int cf_check cleanup_msix(const struct pci_dev *pdev)
> +{
> +    int rc;
> +    struct vpci *vpci = pdev->vpci;
> +    const unsigned int msix_pos = pdev->msix_pos;
> +
> +    if ( !msix_pos )
> +        return 0;
> +
> +    rc = vpci_remove_registers(vpci, msix_control_reg(msix_pos), 2);
> +    if ( rc )
> +    {
> +        printk(XENLOG_ERR "%pd %pp: fail to remove MSIX handlers rc=%d\n",
> +               pdev->domain, &pdev->sbdf, rc);
> +        ASSERT_UNREACHABLE();
> +        return rc;
> +    }
> +
> +    if ( vpci->msix )
> +    {
> +        list_del(&vpci->msix->next);
> +        for ( unsigned int i = 0; i < ARRAY_SIZE(vpci->msix->table); i++ )
> +            if ( vpci->msix->table[i] )
> +                iounmap(vpci->msix->table[i]);
> +
> +        XFREE(vpci->msix);
> +    }
> +
> +    /*
> +     * The driver may not traverse the capability list and think device
> +     * supports MSIX by default. So here let the control register of MSIX
> +     * be Read-Only is to ensure MSIX disabled.
> +     */
> +    rc = vpci_add_register(vpci, vpci_hw_read16, NULL,
> +                           msix_control_reg(msix_pos), 2, NULL);
> +    if ( rc )
> +        printk(XENLOG_ERR "%pd %pp: fail to add MSIX ctrl handler rc=%d\n",
> +               pdev->domain, &pdev->sbdf, rc);

Here as well as for MSI: Wouldn't this better be limited to the init-failure
case? No point in adding a register hook (and possibly emitting a misleading
log message) when we're tearing down anyway. IOW I think the ->cleanup()
hook needs a boolean parameter, unless the distinction of the two cases can
be (reliably) inferred from some other property.

> --- a/xen/drivers/vpci/vpci.c
> +++ b/xen/drivers/vpci/vpci.c
> @@ -321,6 +321,27 @@ void vpci_deassign_device(struct pci_dev *pdev)
>                      &pdev->domain->vpci_dev_assigned_map);
>  #endif
>  
> +    for ( i = 0; i < NUM_VPCI_INIT; i++ )
> +    {
> +        const vpci_capability_t *capability = &__start_vpci_array[i];
> +        const unsigned int cap = capability->id;
> +        unsigned int pos = 0;
> +
> +        if ( !capability->is_ext )
> +            pos = pci_find_cap_offset(pdev->sbdf, cap);
> +        else if ( is_hardware_domain(pdev->domain) )
> +            pos = pci_find_ext_capability(pdev->sbdf, cap);
> +
> +        if ( pos && capability->cleanup )
> +        {
> +            int rc = capability->cleanup(pdev);
> +            if ( rc )
> +                printk(XENLOG_ERR "%pd %pp: clean %s cap %u fail rc=%d\n",
> +                       pdev->domain, &pdev->sbdf,
> +                       capability->is_ext ? "extended" : "legacy", cap, rc);
> +        }
> +    }

With this imo the patch subject is now wrong, too.

Jan