Re: [patch 33/39] PCI/MSI: Sanitize MSI-X checks

Bjorn Helgaas
2022-11-16T16:36:47Z

On Fri, Nov 11, 2022 at 02:55:07PM +0100, Thomas Gleixner wrote:
> There is no point in doing the same sanity checks over and over in a loop
> during MSI-X enablement. Put them in front of the loop and return early
> when they fail.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

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

> ---
> drivers/pci/msi/msi.c | 67 +++++++++++++++++++++++++-------------------------
> 1 file changed, 34 insertions(+), 33 deletions(-)
>
> --- a/drivers/pci/msi/msi.c
> +++ b/drivers/pci/msi/msi.c
> @@ -721,47 +721,31 @@ static int msix_capability_init(struct p
> return ret;
> }
>
> -static int __pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries,
> - int nvec, struct irq_affinity *affd, int flags)
> +static bool pci_msix_validate_entries(struct msix_entry *entries, int nvec, int hwsize)
> {
> - int nr_entries;
> int i, j;
>
> - if (!pci_msi_supported(dev, nvec) || dev->current_state != PCI_D0)
> - return -EINVAL;
> + if (!entries)
> + return true;
>
> - nr_entries = pci_msix_vec_count(dev);
> - if (nr_entries < 0)
> - return nr_entries;
> - if (nvec > nr_entries && !(flags & PCI_IRQ_VIRTUAL))
> - return nr_entries;
> -
> - if (entries) {
> - /* Check for any invalid entries */
> - for (i = 0; i < nvec; i++) {
> - if (entries[i].entry >= nr_entries)
> - return -EINVAL; /* invalid entry */
> - for (j = i + 1; j < nvec; j++) {
> - if (entries[i].entry == entries[j].entry)
> - return -EINVAL; /* duplicate entry */
> - }
> + for (i = 0; i < nvec; i++) {
> + /* Entry within hardware limit? */
> + if (entries[i].entry >= hwsize)
> + return false;
> +
> + /* Check for duplicate entries */
> + for (j = i + 1; j < nvec; j++) {
> + if (entries[i].entry == entries[j].entry)
> + return false;
> }
> }
> -
> - /* Check whether driver already requested for MSI IRQ */
> - if (dev->msi_enabled) {
> - pci_info(dev, "can't enable MSI-X (MSI IRQ already assigned)\n");
> - return -EINVAL;
> - }
> - return msix_capability_init(dev, entries, nvec, affd);
> + return true;
> }
>
> -int __pci_enable_msix_range(struct pci_dev *dev,
> - struct msix_entry *entries, int minvec,
> - int maxvec, struct irq_affinity *affd,
> - int flags)
> +int __pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries, int minvec,
> + int maxvec, struct irq_affinity *affd, int flags)
> {
> - int rc, nvec = maxvec;
> + int hwsize, rc, nvec = maxvec;
>
> if (maxvec < minvec)
> return -ERANGE;
> @@ -774,6 +758,23 @@ int __pci_enable_msix_range(struct pci_d
> if (WARN_ON_ONCE(dev->msix_enabled))
> return -EINVAL;
>
> + if (!pci_msi_supported(dev, nvec) || dev->current_state != PCI_D0)
> + return -EINVAL;
> +
> + hwsize = pci_msix_vec_count(dev);
> + if (hwsize < 0)
> + return hwsize;
> +
> + if (!pci_msix_validate_entries(entries, nvec, hwsize))
> + return -EINVAL;
> +
> + /* PCI_IRQ_VIRTUAL is a horrible hack! */
> + if (nvec > hwsize && !(flags & PCI_IRQ_VIRTUAL))
> + nvec = hwsize;
> +
> + if (nvec < minvec)
> + return -ENOSPC;
> +
> rc = pci_setup_msi_context(dev);
> if (rc)
> return rc;
> @@ -785,7 +786,7 @@ int __pci_enable_msix_range(struct pci_d
> return -ENOSPC;
> }
>
> - rc = __pci_enable_msix(dev, entries, nvec, affd, flags);
> + rc = msix_capability_init(dev, entries, nvec, affd);
> if (rc == 0)
> return nvec;
>
>