[Qemu-devel] [PATCH] virtio-pci: make pci bar layout more flexible.

[Gerd Hoffmann]

This patch makes the bar layout for virtio pci devices configurable.
This is used to
  (a) create different layouts for legacy/transitional vs. modern
      devices.
  (b) make sure we use unused pci bars, by checking
      PCIDevice->io_regions

VirtIOPCIProxy subclasses which need additional pci bars, such as
virtio-vga, just need to make sure they register the additinal bars
before initializing virtio-pci, so the superclass can see the registered
bars and shuffle around the virtio bars accordingly.

The patch also makes sure the modern bar is properly aligned so it can
be a 64bit bar, and the prefetchable + 64bit attributes are enabled.

Signed-off-by: Gerd Hoffmann <kra...@redhat.com>
---
 hw/virtio/virtio-pci.c | 36 +++++++++++++++++++++++++++++++-----
 1 file changed, 31 insertions(+), 5 deletions(-)

diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 6b1f422..a2cfb1f 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -965,8 +965,6 @@ static void virtio_pci_add_mem_cap(VirtIOPCIProxy *proxy,
     PCIDevice *dev = &proxy->pci_dev;
     int offset;
 
-    cap->bar = 2;
-
     offset = pci_add_capability(dev, PCI_CAP_ID_VNDR, 0, cap->cap_len);
     assert(offset > 0);
 
@@ -1232,9 +1230,12 @@ static void virtio_pci_device_write(void *opaque, hwaddr 
addr,
 static void virtio_pci_device_plugged(DeviceState *d)
 {
     VirtIOPCIProxy *proxy = VIRTIO_PCI(d);
+    PCIDevice *pci = PCI_DEVICE(d);
     VirtioBusState *bus = &proxy->bus;
     bool legacy = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_LEGACY);
     bool modern = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_MODERN);
+    uint32_t modern_mem_bar;  /* 64bit bar */
+    uint32_t msix_bar;        /* 32bit bar */
     uint8_t *config;
     uint32_t size;
 
@@ -1248,6 +1249,12 @@ static void virtio_pci_device_plugged(DeviceState *d)
         pci_set_word(config + PCI_SUBSYSTEM_VENDOR_ID,
                      pci_get_word(config + PCI_VENDOR_ID));
         pci_set_word(config + PCI_SUBSYSTEM_ID, virtio_bus_get_vdev_id(bus));
+        msix_bar = 1;
+        modern_mem_bar = 2;
+        while (pci->io_regions[modern_mem_bar].size ||
+               pci->io_regions[modern_mem_bar+1].size) {
+            modern_mem_bar += 2;
+        }
     } else {
         /* pure virtio-1.0 */
         pci_set_word(config + PCI_VENDOR_ID,
@@ -1255,7 +1262,18 @@ static void virtio_pci_device_plugged(DeviceState *d)
         pci_set_word(config + PCI_DEVICE_ID,
                      0x1040 + virtio_bus_get_vdev_id(bus));
         pci_config_set_revision(config, 1);
+        modern_mem_bar = 0;
+        while (pci->io_regions[modern_mem_bar].size ||
+               pci->io_regions[modern_mem_bar+1].size) {
+            modern_mem_bar += 2;
+        }
+        msix_bar = modern_mem_bar + 2;
+        while (pci->io_regions[msix_bar].size) {
+            msix_bar++;
+        }
     }
+    assert(modern_mem_bar <= 4);
+    assert(msix_bar <= 5);
     config[PCI_INTERRUPT_PIN] = 1;
 
 
@@ -1263,29 +1281,34 @@ static void virtio_pci_device_plugged(DeviceState *d)
         struct virtio_pci_cap common = {
             .cfg_type = VIRTIO_PCI_CAP_COMMON_CFG,
             .cap_len = sizeof common,
+            .bar = modern_mem_bar,
             .offset = cpu_to_le32(0x0),
             .length = cpu_to_le32(0x1000),
         };
         struct virtio_pci_cap isr = {
             .cfg_type = VIRTIO_PCI_CAP_ISR_CFG,
             .cap_len = sizeof isr,
+            .bar = modern_mem_bar,
             .offset = cpu_to_le32(0x1000),
             .length = cpu_to_le32(0x1000),
         };
         struct virtio_pci_cap device = {
             .cfg_type = VIRTIO_PCI_CAP_DEVICE_CFG,
             .cap_len = sizeof device,
+            .bar = modern_mem_bar,
             .offset = cpu_to_le32(0x2000),
             .length = cpu_to_le32(0x1000),
         };
         struct virtio_pci_notify_cap notify = {
             .cap.cfg_type = VIRTIO_PCI_CAP_NOTIFY_CFG,
             .cap.cap_len = sizeof notify,
+            .cap.bar = modern_mem_bar,
             .cap.offset = cpu_to_le32(0x3000),
             .cap.length = cpu_to_le32(QEMU_VIRTIO_PCI_QUEUE_MEM_MULT *
                                       VIRTIO_PCI_QUEUE_MAX),
             .notify_off_multiplier = 
cpu_to_le32(QEMU_VIRTIO_PCI_QUEUE_MEM_MULT),
         };
+        uint32_t modern_mem_attr;
 
         static const MemoryRegionOps common_ops = {
             .read = virtio_pci_common_read,
@@ -1359,12 +1382,15 @@ static void virtio_pci_device_plugged(DeviceState *d)
                               QEMU_VIRTIO_PCI_QUEUE_MEM_MULT *
                               VIRTIO_PCI_QUEUE_MAX);
         memory_region_add_subregion(&proxy->modern_bar, 0x3000, 
&proxy->notify);
-        pci_register_bar(&proxy->pci_dev, 2, PCI_BASE_ADDRESS_SPACE_MEMORY,
-                         &proxy->modern_bar);
+        modern_mem_attr = (PCI_BASE_ADDRESS_SPACE_MEMORY |
+                           PCI_BASE_ADDRESS_MEM_PREFETCH |
+                           PCI_BASE_ADDRESS_MEM_TYPE_64);
+        pci_register_bar(&proxy->pci_dev, modern_mem_bar,
+                         modern_mem_attr, &proxy->modern_bar);
     }
 
     if (proxy->nvectors &&
-        msix_init_exclusive_bar(&proxy->pci_dev, proxy->nvectors, 1)) {
+        msix_init_exclusive_bar(&proxy->pci_dev, proxy->nvectors, msix_bar)) {
         error_report("unable to init msix vectors to %" PRIu32,
                      proxy->nvectors);
         proxy->nvectors = 0;
-- 
1.8.3.1