On Fri, Nov 11, 2022 at 02:58:49PM +0100, Thomas Gleixner wrote:
> Dynamic MSI-X vector allocation post MSI-X allows to allocate vectors at a
> given index or at any free index in the available table range.
Is "post MSI-X" missing something? "post MSI-X enablement" or
something?
> The latter
> requires that the core code selects the index at descriptor allocation time.
>
> This requires that the PCI/MSI-X specific setup of the MSI-X descriptor,
> which is partially depending on the chosen index happens after allocation.
Is there a comma missing after "index"? I.e., setup of the descriptor
partially depends on the chosen index? And the above requires that
setup happens after allocation?
> Implement the prepare_desc() op in the PCI/MSI-X specific msi_domain_ops
> which is invoked before the core interrupt descriptor and the associated
> Linux interrupt number is allocated. That callback is also provided for the
> upcoming PCI/IMS implementations so the implementation specific interrupt
> domain can do their domain specific initialization of the MSI descriptors.
>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> ---
> drivers/pci/msi/irqdomain.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> --- a/drivers/pci/msi/irqdomain.c
> +++ b/drivers/pci/msi/irqdomain.c
> @@ -202,6 +202,14 @@ static void pci_unmask_msix(struct irq_d
> pci_msix_unmask(irq_data_get_msi_desc(data));
> }
>
> +static void pci_msix_prepare_desc(struct irq_domain *domain, msi_alloc_info_t *arg,
> + struct msi_desc *desc)
> +{
> + /* Don't fiddle with preallocated MSI descriptors */
> + if (!desc->pci.mask_base)
> + msix_prepare_msi_desc(to_pci_dev(desc->dev), desc);
> +}
> +
> static struct msi_domain_template pci_msix_template = {
> .chip = {
> .name = "PCI-MSIX",
> @@ -212,6 +220,7 @@ static struct msi_domain_template pci_ms
> },
>
> .ops = {
> + .prepare_desc = pci_msix_prepare_desc,
> .set_desc = pci_device_domain_set_desc,
> },
>
>
