Commit 4bb571d8 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin
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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: default avatarMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: default avatarPeter Xu <peterx@redhat.com>
Reviewed-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent ad584d37

hw/pci/pcie.c

+7 −4
Original line number Diff line number Diff line
@@ -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);