Re: [PATCH v5 10/10] vpci/msix: Free MSIX resources when init_msix() fails

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

On Mon, May 26, 2025 at 05:45:59PM +0800, Jiqian Chen wrote:
> When init_msix() fails, current logic return fail and free MSIX-related
> resources in vpci_deassign_device(). But the previous new changes will
> hide MSIX capability and return success, it can't reach
> vpci_deassign_device() to remove resources if hiding success, so those
> resources must be removed in cleanup function of MSIX.
> 
> To do that, implement cleanup function for MSIX.
> 
> Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>



> ---
> cc: "Roger Pau Monné" <roger.pau@xxxxxxxxxx>
> ---
> v4->v5 changes:
> * Change definition "static void cleanup_msix" to "static int cf_check 
> cleanup_msix" since cleanup hook is changed to be int.
> * Add a read-only register for MSIX Control Register in the end of 
> cleanup_msix().
> 
> v3->v4 changes:
> * Change function name from fini_msix() to cleanup_msix().
> * Change to use XFREE to free vpci->msix.
> * In cleanup function, change the sequence of check and remove action 
> according to init_msix().
> 
> v2->v3 changes:
> * Remove unnecessary clean operations in fini_msix().
> 
> v1->v2 changes:
> new patch.
> 
> Best regards,
> Jiqian Chen.
> ---
>  xen/drivers/vpci/msix.c | 29 ++++++++++++++++++++++++++++-
>  1 file changed, 28 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/drivers/vpci/msix.c b/xen/drivers/vpci/msix.c
> index 674815ead025..cf79320d3b6f 100644
> --- a/xen/drivers/vpci/msix.c
> +++ b/xen/drivers/vpci/msix.c
> @@ -655,6 +655,33 @@ int vpci_make_msix_hole(const struct pci_dev *pdev)
>      return 0;
>  }
>  
> +static int cf_check cleanup_msix(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 )
> +        return rc;
> +
> +    if ( !vpci->msix )
> +        return 0;

You cannot short-circuit here, as it then prevents adding the dummy
handlers done in the last return.

> +
> +    for ( unsigned int i = 0; i < ARRAY_SIZE(vpci->msix->table); i++ )
> +        if ( vpci->msix->table[i] )
> +            iounmap(vpci->msix->table[i]);
> +
> +    list_del(&vpci->msix->next);
> +    XFREE(vpci->msix);
> +
> +    return vpci_add_register(pdev->vpci, vpci_hw_read16, NULL,
> +                             msix_control_reg(msix_pos), 2, NULL);

The above needs to be added even if !vpci->msix.

Thanks, Roger.