5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Naveen Naidu <naveennaidu479@xxxxxxxxx> [ Upstream commit 57bdeef4716689d9b0e3571034d65cf420f6efcd ] A config or MMIO read from a PCI device that doesn't exist or doesn't respond causes a PCI error. There's no real data to return to satisfy the CPU read, so most hardware fabricates ~0 data. Add a PCI_ERROR_RESPONSE definition for that and use it where appropriate to make these checks consistent and easier to find. Also add helper definitions PCI_SET_ERROR_RESPONSE() and PCI_POSSIBLE_ERROR() to make the code more readable. Suggested-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> Link: https://lore.kernel.org/r/55563bf4dfc5d3fdc96695373c659d099bf175b1.1637243717.git.naveennaidu479@xxxxxxxxx Signed-off-by: Naveen Naidu <naveennaidu479@xxxxxxxxx> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> Reviewed-by: Pali Rohár <pali@xxxxxxxxxx> Stable-dep-of: c625dabbf1c4 ("x86/amd_nb: Check for invalid SMN reads") Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- include/linux/pci.h | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/include/linux/pci.h b/include/linux/pci.h index 1cd5caa567cf5..7edc6de9e88c2 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -129,6 +129,15 @@ enum pci_interrupt_pin { /* The number of legacy PCI INTx interrupts */ #define PCI_NUM_INTX 4 +/* + * Reading from a device that doesn't respond typically returns ~0. A + * successful read from a device may also return ~0, so you need additional + * information to reliably identify errors. + */ +#define PCI_ERROR_RESPONSE (~0ULL) +#define PCI_SET_ERROR_RESPONSE(val) (*(val) = ((typeof(*(val))) PCI_ERROR_RESPONSE)) +#define PCI_POSSIBLE_ERROR(val) ((val) == ((typeof(val)) PCI_ERROR_RESPONSE)) + /* * pci_power_t values must match the bits in the Capabilities PME_Support * and Control/Status PowerState fields in the Power Management capability. -- 2.43.0
