PCI/MSI: Deal with devices lying about their MSI mask capability

commit 2226667a145db2e1f314d7f57fd644fe69863ab9 upstream.

It appears that some devices are lying about their mask capability,
pretending that they don't have it, while they actually do.
The net result is that now that we don't enable MSIs on such
endpoint.

Add a new per-device flag to deal with this. Further patches will
make use of it, sadly.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20211104180130.3825416-2-maz@kernel.org
Cc: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 30bec2482e2733ffb0eb378e1284897f1ea3a20a..da5fbfcda433d34ab4d56595b356e9d4b4eb8ca8 100644 (file)
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -585,6 +585,9 @@ msi_setup_entry(struct pci_dev *dev, int nvec, struct irq_affinity *affd)
                goto out;
 
        pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &control);
+       /* Lies, damned lies, and MSIs */
+       if (dev->dev_flags & PCI_DEV_FLAGS_HAS_MSI_MASKING)
+               control |= PCI_MSI_FLAGS_MASKBIT;
 
        entry->msi_attrib.is_msix       = 0;
        entry->msi_attrib.is_64         = !!(control & PCI_MSI_FLAGS_64BIT);

diff --git a/include/linux/pci.h b/include/linux/pci.h
index acbed2ecf6e8ce599a65a3169899b6b25dd93981..25acd447c9227afb40998e8bd47ec962b96352e5 100644 (file)
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -227,6 +227,8 @@ enum pci_dev_flags {
        PCI_DEV_FLAGS_NO_FLR_RESET = (__force pci_dev_flags_t) (1 << 10),
        /* Don't use Relaxed Ordering for TLPs directed at this device */
        PCI_DEV_FLAGS_NO_RELAXED_ORDERING = (__force pci_dev_flags_t) (1 << 11),
+       /* Device does honor MSI masking despite saying otherwise */
+       PCI_DEV_FLAGS_HAS_MSI_MASKING = (__force pci_dev_flags_t) (1 << 12),
 };
 
 enum pci_irq_reroute_variant {