Re: [PATCH v5 09/10] vpci/msi: Free MSI resources when init_msi() fails

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

On Mon, May 26, 2025 at 05:45:58PM +0800, Jiqian Chen wrote:
> When init_msi() fails, current logic return fail and free MSI-related
> resources in vpci_deassign_device(). But the previous new changes will
> hide MSI 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 MSI.
> 
> To do that, implement cleanup function for MSI.
> 
> Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
> ---
> cc: "Roger Pau Monné" <roger.pau@xxxxxxxxxx>
> ---
> v4->v5 changes:
> * Change definition "static void cleanup_msi" to "static int cf_check 
> cleanup_msi" since cleanup hook is changed to be int.
> * Add a read-only register for MSI Control Register in the end of cleanup_msi.
> 
> v3->v4 changes:
> * Change function name from fini_msi() to cleanup_msi().
> * Remove unnecessary comment.
> * Change to use XFREE to free vpci->msi.
> 
> v2->v3 changes:
> * Remove all fail path, and use fini_msi() hook instead.
> * Change the method to calculating the size of msi registers.
> 
> v1->v2 changes:
> * Added a new function fini_msi to free all MSI resources instead of using an 
> array to record registered registers.
> 
> Best regards,
> Jiqian Chen.
> ---
>  xen/drivers/vpci/msi.c | 29 ++++++++++++++++++++++++++++-
>  1 file changed, 28 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/drivers/vpci/msi.c b/xen/drivers/vpci/msi.c
> index 2d45c7867de7..4e106c39efae 100644
> --- a/xen/drivers/vpci/msi.c
> +++ b/xen/drivers/vpci/msi.c
> @@ -193,6 +193,33 @@ static void cf_check mask_write(
>      msi->mask = val;
>  }
>  
> +static int cf_check cleanup_msi(struct pci_dev *pdev)
> +{
> +    int rc;
> +    unsigned int end, size;
> +    struct vpci *vpci = pdev->vpci;
> +    const unsigned int msi_pos = pdev->msi_pos;
> +    const unsigned int ctrl = msi_control_reg(msi_pos);
> +
> +    if ( !msi_pos || !vpci->msi )

Possibly same request as the previous patch, msi_pos should be after
the PCI standard header.

Thanks, Roger.