Commit cf761e3d authored by Jonathan Currier's avatar Jonathan Currier Committed by Thomas Gleixner
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PCI/MSI: Add an option to write MSIX ENTRY_DATA before any reads 



Commit 7d5ec3d3 ("PCI/MSI: Mask all unused MSI-X entries") introduced a
readl() from ENTRY_VECTOR_CTRL before the writel() to ENTRY_DATA.

This is correct, however some hardware, like the Sun Neptune chips, the NIU
module, will cause an error and/or fatal trap if any MSIX table entry is
read before the corresponding ENTRY_DATA field is written to.

Add an optional early writel() in msix_prepare_msi_desc().

Fixes: 7d5ec3d3 ("PCI/MSI: Mask all unused MSI-X entries")
Signed-off-by: default avatarJonathan Currier <dullfire@yahoo.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20241117234843.19236-2-dullfire@yahoo.com
parent 8ffd015d

drivers/pci/msi/msi.c

+3 −0
Original line number Diff line number Diff line
@@ -615,6 +615,9 @@ void msix_prepare_msi_desc(struct pci_dev *dev, struct msi_desc *desc) 
		void __iomem *addr = pci_msix_desc_addr(desc);



		desc->pci.msi_attrib.can_mask = 1;

		/* Workaround for SUN NIU insanity, which requires write before read */

		if (dev->dev_flags & PCI_DEV_FLAGS_MSIX_TOUCH_ENTRY_DATA_FIRST)

			writel(0, addr + PCI_MSIX_ENTRY_DATA);

		desc->pci.msix_ctrl = readl(addr + PCI_MSIX_ENTRY_VECTOR_CTRL);

	}

}

include/linux/pci.h

+2 −0
Original line number Diff line number Diff line
@@ -245,6 +245,8 @@ enum pci_dev_flags { 
	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),

	/* Device requires write to PCI_MSIX_ENTRY_DATA before any MSIX reads */

	PCI_DEV_FLAGS_MSIX_TOUCH_ENTRY_DATA_FIRST = (__force pci_dev_flags_t) (1 << 13),

};



enum pci_irq_reroute_variant {