[Qemu-devel] [RFC v4 3/9] vfio: add pcie extanded capability support

[Chen Fan]

For vfio pcie device, we could expose the extanded capability on
PCIE bus. in order to avoid config space broken, we introduce
a copy config for parsing extended caps. and rebuild the pcie
extended config space.

Signed-off-by: Chen Fan <address@hidden>
---
 hw/vfio/pci.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 82 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 84e9d99..96cb52b 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -2482,6 +2482,21 @@ static uint8_t vfio_std_cap_max_size(PCIDevice *pdev, 
uint8_t pos)
     return next - pos;
 }
 
+
+static uint16_t vfio_ext_cap_max_size(const uint8_t *config, uint16_t pos)
+{
+    uint16_t tmp, next = PCIE_CONFIG_SPACE_SIZE - 1;
+
+    for (tmp = PCI_CONFIG_SPACE_SIZE; tmp;
+        tmp = PCI_EXT_CAP_NEXT(pci_get_long(config + tmp))) {
+        if (tmp > pos && tmp < next) {
+            next = tmp;
+        }
+    }
+
+    return next - pos;
+}
+
 static void vfio_set_word_bits(uint8_t *buf, uint16_t val, uint16_t mask)
 {
     pci_set_word(buf, (pci_get_word(buf) & ~mask) | val);
@@ -2705,16 +2720,82 @@ static int vfio_add_std_cap(VFIOPCIDevice *vdev, 
uint8_t pos)
     return 0;
 }
 
+static int vfio_add_ext_cap(VFIOPCIDevice *vdev, const uint8_t *config,
+                            uint16_t pos)
+{
+    PCIDevice *pdev = &vdev->pdev;
+    uint32_t header;
+    uint16_t cap_id, next, size;
+    uint8_t cap_ver;
+    int ret;
+
+    header = pci_get_long(config + pos);
+    cap_id = PCI_EXT_CAP_ID(header);
+    cap_ver = PCI_EXT_CAP_VER(header);
+    next = PCI_EXT_CAP_NEXT(header);
+
+    /*
+     * If it becomes important to configure extended capabilities to their
+     * actual size, use this as the default when it's something we don't
+     * recognize. Since QEMU doesn't actually handle many of the config
+     * accesses, exact size doesn't seem worthwhile.
+     */
+    size = vfio_ext_cap_max_size(config, pos);
+
+    pcie_add_capability(pdev, cap_id, cap_ver, pos, size);
+    if (pos == PCI_CONFIG_SPACE_SIZE) {
+        /* Begin the rebuild, we should set the next offset zero. */
+        pci_set_long(pdev->config + pos, PCI_EXT_CAP(cap_id, cap_ver, 0));
+    }
+
+    /* Use emulated header pointer to allow dropping extended caps */
+    pci_set_long(vdev->emulated_config_bits + pos, 0xffffffff);
+
+    if (next) {
+        ret = vfio_add_ext_cap(vdev, config, next);
+        if (ret) {
+            return ret;
+        }
+    }
+
+    return 0;
+}
+
 static int vfio_add_capabilities(VFIOPCIDevice *vdev)
 {
     PCIDevice *pdev = &vdev->pdev;
+    int ret;
+    uint8_t *config;
 
     if (!(pdev->config[PCI_STATUS] & PCI_STATUS_CAP_LIST) ||
         !pdev->config[PCI_CAPABILITY_LIST]) {
         return 0; /* Nothing to add */
     }
 
-    return vfio_add_std_cap(vdev, pdev->config[PCI_CAPABILITY_LIST]);
+    ret = vfio_add_std_cap(vdev, pdev->config[PCI_CAPABILITY_LIST]);
+    if (ret) {
+        return ret;
+    }
+
+    /* on PCI bus, it doesn't make sense to expose extended capabilities. */
+    if (!pci_bus_is_express(vdev->pdev.bus) ||
+        !pci_get_long(pdev->config + PCI_CONFIG_SPACE_SIZE)) {
+        return 0;
+    }
+
+    /*
+     * In order to avoid config space broken, here using a copy config to
+     * parse extended capabilitiess.
+     */
+    config = g_malloc0(vdev->config_size);
+    if (!config) {
+        return -ENOMEM;
+    }
+    memcpy(config, pdev->config, vdev->config_size);
+    ret = vfio_add_ext_cap(vdev, config, PCI_CONFIG_SPACE_SIZE);
+
+    g_free(config);
+    return ret;
 }
 
 static void vfio_pci_pre_reset(VFIOPCIDevice *vdev)
-- 
1.9.3