Commit 2226667a authored by Marc Zyngier's avatar Marc Zyngier Committed by Thomas Gleixner
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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: default avatarMarc Zyngier <maz@kernel.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20211104180130.3825416-2-maz@kernel.org
Cc: Bjorn Helgaas <helgaas@kernel.org>
parent 9c8e9c96

drivers/pci/msi.c

+3 −0
Original line number Diff line number Diff line
@@ -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);

include/linux/pci.h

+2 −0
Original line number Diff line number Diff line
@@ -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 {