From: Jonathan Currier dullfire@yahoo.com
[ 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 dullfire@yahoo.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/20241117234843.19236-2-dullfire@yahoo.com [ Applied workaround to msix_setup_msi_descs() instead of msix_prepare_msi_desc() ] Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pci/msi/msi.c | 3 +++ include/linux/pci.h | 2 ++ 2 files changed, 5 insertions(+)
diff --git a/drivers/pci/msi/msi.c b/drivers/pci/msi/msi.c index c5cc3e453fd0c..7110aed956c75 100644 --- a/drivers/pci/msi/msi.c +++ b/drivers/pci/msi/msi.c @@ -534,6 +534,9 @@ static int msix_setup_msi_descs(struct pci_dev *dev, void __iomem *base,
if (desc.pci.msi_attrib.can_mask) { 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 df36df4695ed5..59dfa59d6d597 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -244,6 +244,8 @@ 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 {