The current implementation of pci_find_space does not correctly align PCI capabilities in the PCI configuration space. It also does not support PCI-Express devices. This patch fixes these issues.
Thanks to Alex Williamson for feedback. Signed-off-by: Matt Renzelmann <m...@cs.wisc.edu> --- Re-sending to add CC Michael S. Tsirkin <m...@redhat.com>. Thanks Andreas for pointing out my mistake. hw/pci.c | 36 ++++++++++++++++++++++++++++-------- 1 files changed, 28 insertions(+), 8 deletions(-) diff --git a/hw/pci.c b/hw/pci.c index 2ca6ff6..4b617f6 100644 --- a/hw/pci.c +++ b/hw/pci.c @@ -1644,19 +1644,39 @@ PCIDevice *pci_create_simple(PCIBus *bus, int devfn, const char *name) return pci_create_simple_multifunction(bus, devfn, false, name); } -static int pci_find_space(PCIDevice *pdev, uint8_t size) +static int pci_find_space(PCIDevice *pdev, uint32_t start, + uint32_t end, uint32_t size) { - int config_size = pci_config_size(pdev); - int offset = PCI_CONFIG_HEADER_SIZE; + int offset = start; int i; - for (i = PCI_CONFIG_HEADER_SIZE; i < config_size; ++i) - if (pdev->used[i]) - offset = i + 1; - else if (i - offset + 1 == size) + uint32_t *dword_used = &pdev->used[start]; + + assert(pci_config_size(pdev) >= end); + assert(!(start & 0x3)); + + /* This approach ensures the capability is dword-aligned, as + required by the PCI and PCI-E specifications */ + for (i = start; i < end; i += 4, dword_used++) { + if (*dword_used) { + offset = i + 4; + } else if (i - offset + 4 >= size) { return offset; + } + } + return 0; } +static int pci_find_legacy_space(PCIDevice *pdev, uint8_t size) { + return pci_find_space(pdev, PCI_CONFIG_HEADER_SIZE, + PCI_CONFIG_SPACE_SIZE, size); +} + +static int pci_find_express_space(PCIDevice *pdev, uint16_t size) { + return pci_find_space(pdev, PCI_CONFIG_SPACE_SIZE, + PCIE_CONFIG_SPACE_SIZE, size); +} + static uint8_t pci_find_capability_list(PCIDevice *pdev, uint8_t cap_id, uint8_t *prev_p) { @@ -1844,7 +1864,7 @@ int pci_add_capability(PCIDevice *pdev, uint8_t cap_id, int i, overlapping_cap; if (!offset) { - offset = pci_find_space(pdev, size); + offset = pci_find_legacy_space(pdev, size); if (!offset) { return -ENOSPC; } -- 1.7.5.4