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

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>
This commit is contained in:
Marc Zyngier 2021-11-04 18:01:29 +00:00 committed by Thomas Gleixner
parent 9c8e9c9681
commit 2226667a14
2 changed files with 5 additions and 0 deletions
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3
drivers/pci/msi.c
View File

@ -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);

2
include/linux/pci.h
View File

@ -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 {