Re: [patch 36/39] PCI/MSI: Validate MSIX contiguous restriction early

Bjorn Helgaas
2022-11-16T16:39:49Z

On Fri, Nov 11, 2022 at 02:55:12PM +0100, Thomas Gleixner wrote:
> With interrupt domains the sanity check for MSI-X vector validation can be
> done _before_ any allocation happens. The sanity check only applies to the
> allocation functions which have an 'entries' array argument. The entries
> array is filled by the caller with the requested MSI-X indicies. Some drivers
> have gaps in the index space which is not supported on all architectures.
>
> The PCI/MSI irqdomain has a 'feature' bit to enforce this validation late
> during the allocation phase.
>
> Just do it right away before doing any other work along with the other
> sanity checks on that array.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

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

s/indicies/indices/ (commit log)
s/irqdomain/irq domain/? IIRC previous logs used "irq domain"
s/MSIX/MSI-X/ (subject line)

> ---
> drivers/pci/msi/msi.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> --- a/drivers/pci/msi/msi.c
> +++ b/drivers/pci/msi/msi.c
> @@ -725,13 +725,17 @@ static int msix_capability_init(struct p
> return ret;
> }
>
> -static bool pci_msix_validate_entries(struct msix_entry *entries, int nvec, int hwsize)
> +static bool pci_msix_validate_entries(struct pci_dev *dev, struct msix_entry *entries,
> + int nvec, int hwsize)
> {
> + bool nogap;
> int i, j;
>
> if (!entries)
> return true;
>
> + nogap = pci_msi_domain_supports(dev, MSI_FLAG_MSIX_CONTIGUOUS, DENY_LEGACY);
> +
> for (i = 0; i < nvec; i++) {
> /* Entry within hardware limit? */
> if (entries[i].entry >= hwsize)
> @@ -742,6 +746,9 @@ static bool pci_msix_validate_entries(st
> if (entries[i].entry == entries[j].entry)
> return false;
> }
> + /* Check for unsupported gaps */
> + if (nogap && entries[i].entry != i)
> + return false;
> }
> return true;
> }
> @@ -773,7 +780,7 @@ int __pci_enable_msix_range(struct pci_d
> if (hwsize < 0)
> return hwsize;
>
> - if (!pci_msix_validate_entries(entries, nvec, hwsize))
> + if (!pci_msix_validate_entries(dev, entries, nvec, hwsize))
> return -EINVAL;
>
> /* PCI_IRQ_VIRTUAL is a horrible hack! */
>