The following commit has been merged into the irq/core branch of tip:
Commit-ID: da181dc974ad667579baece33c2c8d2d1e4558d5 Gitweb: https://git.kernel.org/tip/da181dc974ad667579baece33c2c8d2d1e4558d5 Author: Thomas Gleixner tglx@linutronix.de AuthorDate: Thu, 29 Jul 2021 23:51:42 +02:00 Committer: Thomas Gleixner tglx@linutronix.de CommitterDate: Tue, 10 Aug 2021 10:59:20 +02:00
PCI/MSI: Enforce that MSI-X table entry is masked for update
The specification (PCIe r5.0, sec 6.1.4.5) states:
For MSI-X, a function is permitted to cache Address and Data values from unmasked MSI-X Table entries. However, anytime software unmasks a currently masked MSI-X Table entry either by clearing its Mask bit or by clearing the Function Mask bit, the function must update any Address or Data values that it cached from that entry. If software changes the Address or Data value of an entry while the entry is unmasked, the result is undefined.
The Linux kernel's MSI-X support never enforced that the entry is masked before the entry is modified hence the Fixes tag refers to a commit in: git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Enforce the entry to be masked across the update.
There is no point in enforcing this to be handled at all possible call sites as this is just pointless code duplication and the common update function is the obvious place to enforce this.
Fixes: f036d4ea5fa7 ("[PATCH] ia32 Message Signalled Interrupt support") Reported-by: Kevin Tian kevin.tian@intel.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Tested-by: Marc Zyngier maz@kernel.org Reviewed-by: Marc Zyngier maz@kernel.org Acked-by: Bjorn Helgaas bhelgaas@google.com Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20210729222542.462096385@linutronix.de
--- drivers/pci/msi.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c index 57c9ec9..7ee1ac4 100644 --- a/drivers/pci/msi.c +++ b/drivers/pci/msi.c @@ -289,13 +289,28 @@ void __pci_write_msi_msg(struct msi_desc *entry, struct msi_msg *msg) /* Don't touch the hardware now */ } else if (entry->msi_attrib.is_msix) { void __iomem *base = pci_msix_desc_addr(entry); + bool unmasked = !(entry->masked & PCI_MSIX_ENTRY_CTRL_MASKBIT);
if (!base) goto skip;
+ /* + * The specification mandates that the entry is masked + * when the message is modified: + * + * "If software changes the Address or Data value of an + * entry while the entry is unmasked, the result is + * undefined." + */ + if (unmasked) + __pci_msix_desc_mask_irq(entry, PCI_MSIX_ENTRY_CTRL_MASKBIT); + writel(msg->address_lo, base + PCI_MSIX_ENTRY_LOWER_ADDR); writel(msg->address_hi, base + PCI_MSIX_ENTRY_UPPER_ADDR); writel(msg->data, base + PCI_MSIX_ENTRY_DATA); + + if (unmasked) + __pci_msix_desc_mask_irq(entry, 0); } else { int pos = dev->msi_cap; u16 msgctl;