Re: [patch V2 25/36] PCI/MSI: Provide MSI_FLAG_MSIX_CONTIGUOUS

Bjorn Helgaas
2021-12-07T21:05:42Z

On Mon, Dec 06, 2021 at 11:39:36PM +0100, Thomas Gleixner wrote:
> Provide a domain info flag which makes the core code check for a contiguous
> MSI-X index on allocation. That's simpler than checking it at some other
> domain callback in architecture code.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
> drivers/pci/msi/irqdomain.c | 16 ++++++++++++++--
> include/linux/msi.h | 2 ++
> 2 files changed, 16 insertions(+), 2 deletions(-)
>
> --- a/drivers/pci/msi/irqdomain.c
> +++ b/drivers/pci/msi/irqdomain.c
> @@ -89,9 +89,21 @@ static int pci_msi_domain_check_cap(stru
> if (pci_msi_desc_is_multi_msi(desc) &&
> !(info->flags & MSI_FLAG_MULTI_PCI_MSI))
> return 1;
> - else if (desc->pci.msi_attrib.is_msix && !(info->flags & MSI_FLAG_PCI_MSIX))
> - return -ENOTSUPP;
>
> + if (desc->pci.msi_attrib.is_msix) {
> + if (!(info->flags & MSI_FLAG_PCI_MSIX))
> + return -ENOTSUPP;
> +
> + if (info->flags & MSI_FLAG_MSIX_CONTIGUOUS) {
> + unsigned int idx = 0;
> +
> + /* Check for gaps in the entry indices */
> + for_each_msi_entry(desc, dev) {
> + if (desc->msi_index != idx++)
> + return -ENOTSUPP;
> + }
> + }
> + }
> return 0;
> }
>
> --- a/include/linux/msi.h
> +++ b/include/linux/msi.h
> @@ -376,6 +376,8 @@ enum {
> MSI_FLAG_LEVEL_CAPABLE = (1 << 6),
> /* Populate sysfs on alloc() and destroy it on free() */
> MSI_FLAG_DEV_SYSFS = (1 << 7),
> + /* MSI-X entries must be contiguous */
> + MSI_FLAG_MSIX_CONTIGUOUS = (1 << 8),
> };
>
> int msi_domain_set_affinity(struct irq_data *data, const struct cpumask *mask,
>