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 <m...@redhat.com>
---
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 cbd4bb4..f4dd177 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);
--
MST
