From: Jonathan Currier Date: Sat, 6 Sep 2025 19:50:14 +0000 (-0400) Subject: PCI/MSI: Add an option to write MSIX ENTRY_DATA before any reads X-Git-Tag: v6.6.105~39 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b088ae4e41845d0a93c0acf072e72eca4df20085;p=thirdparty%2Fkernel%2Fstable.git PCI/MSI: Add an option to write MSIX ENTRY_DATA before any reads [ Upstream commit cf761e3dacc6ad5f65a4886d00da1f9681e6805a ] Commit 7d5ec3d36123 ("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: 7d5ec3d36123 ("PCI/MSI: Mask all unused MSI-X entries") Signed-off-by: Jonathan Currier Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/20241117234843.19236-2-dullfire@yahoo.com [ Adjust context ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/pci/msi/msi.c b/drivers/pci/msi/msi.c index 053bb9fac6e3e..b638731aa5ff2 100644 --- a/drivers/pci/msi/msi.c +++ b/drivers/pci/msi/msi.c @@ -610,6 +610,9 @@ void msix_prepare_msi_desc(struct pci_dev *dev, struct msi_desc *desc) if (desc->pci.msi_attrib.can_mask) { void __iomem *addr = pci_msix_desc_addr(desc); + /* 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); } } diff --git a/include/linux/pci.h b/include/linux/pci.h index ac5bd1718af24..0511f6f9a4e6a 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -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 {