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 ea6371eb9b257959c3b0ad1d243cf28536caa6dc..e2dedfa9072db483d4c2c08a91a15b31990d369d 100644 (file)
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -477,6 +477,9 @@ 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 cd8aa6fce2041c47725b2009f34669ac274f2290..152a4d74f87f02aa3c2ce072f254690615eb7bf6 100644 (file)
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -233,6 +233,8 @@ 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 {