From 4bb571d857d973d9308d9fdb1f48d983d6639bd4 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Wed, 15 Feb 2017 22:37:45 +0200 Subject: [PATCH] pci/pcie: don't assume cap id 0 is reserved VFIO actually wants to create a capability with ID == 0. This is done to make guest drivers skip the given capability. pcie_add_capability then trips up on this capability when looking for end of capability list. To support this use-case, it's easy enough to switch to e.g. 0xffffffff for these comparisons - we can be sure it will never match a 16-bit capability ID. Signed-off-by: Michael S. Tsirkin Reviewed-by: Peter Xu Reviewed-by: Alex Williamson --- hw/pci/pcie.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c index cbd4bb4f8c..f4dd177bc4 100644 --- a/hw/pci/pcie.c +++ b/hw/pci/pcie.c @@ -610,7 +610,8 @@ bool pcie_cap_is_arifwd_enabled(const PCIDevice *dev) * uint16_t ext_cap_size */ -static uint16_t pcie_find_capability_list(PCIDevice *dev, uint16_t cap_id, +/* Passing a cap_id value > 0xffff will return 0 and put end of list in prev */ +static uint16_t pcie_find_capability_list(PCIDevice *dev, uint32_t cap_id, uint16_t *prev_p) { uint16_t prev = 0; @@ -679,9 +680,11 @@ void pcie_add_capability(PCIDevice *dev, } else { uint16_t prev; - /* 0 is reserved cap id. use internally to find the last capability - in the linked list */ - next = pcie_find_capability_list(dev, 0, &prev); + /* + * 0xffffffff is not a valid cap id (it's a 16 bit field). use + * internally to find the last capability in the linked list. + */ + next = pcie_find_capability_list(dev, 0xffffffff, &prev); assert(prev >= PCI_CONFIG_SPACE_SIZE); assert(next == 0); -- 2.11.4.GIT