[Qemu-devel] [RfC PATCH] virtio-pci: place msix regions in modern virtio bar

[Gerd Hoffmann <kraxel@redhat.com>]

Only for legacy-free virtio devices, to avoid unpleasent
surprises with old drivers.

mtree snippet:

    00000000fea00000-00000000fea7ffff (prio 1, RW): virtio-pci
      00000000fea00000-00000000fea00fff (prio 0, RW): virtio-pci-common
      00000000fea01000-00000000fea01fff (prio 0, RW): virtio-pci-isr
      00000000fea02000-00000000fea02fff (prio 0, RW): virtio-pci-device
      00000000fea03000-00000000fea42fff (prio 0, RW): virtio-pci-notify
      00000000fea7e000-00000000fea7e02f (prio 0, RW): msix-table
      00000000fea7f000-00000000fea7f007 (prio 0, RW): msix-pba

Applies on top of mst's virtio-1.0 branch, plus my three virtio-pci
patches posted to the list yesterday.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/virtio/virtio-pci.c | 39 +++++++++++++++++++++++++++------------
 1 file changed, 27 insertions(+), 12 deletions(-)

diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index ba1405f..934ca7a 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -1235,7 +1235,7 @@ static void virtio_pci_device_plugged(DeviceState *d)
     bool modern = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_MODERN);
     int modern_mem_bar;
     uint8_t *config;
-    uint32_t size;
+    uint32_t modern_mem_size, legacy_io_size;
 
     config = proxy->pci_dev.config;
     if (proxy->class_code) {
@@ -1339,9 +1339,10 @@ static void virtio_pci_device_plugged(DeviceState *d)
         virtio_pci_add_mem_cap(proxy, &notify.cap);
 
         virtio_add_feature(&proxy->host_features, VIRTIO_F_VERSION_1);
+        modern_mem_size = 2 * QEMU_VIRTIO_PCI_QUEUE_MEM_MULT *
+            VIRTIO_PCI_QUEUE_MAX;
         memory_region_init(&proxy->modern_bar, OBJECT(proxy), "virtio-pci",
-                           2 * QEMU_VIRTIO_PCI_QUEUE_MEM_MULT *
-                           VIRTIO_PCI_QUEUE_MAX);
+                           modern_mem_size);
         memory_region_init_io(&proxy->common, OBJECT(proxy),
                               &common_ops,
                               proxy,
@@ -1369,25 +1370,39 @@ static void virtio_pci_device_plugged(DeviceState *d)
                          &proxy->modern_bar);
     }
 
-    if (proxy->nvectors &&
-        msix_init_exclusive_bar(&proxy->pci_dev, proxy->nvectors, 1)) {
-        error_report("unable to init msix vectors to %" PRIu32,
-                     proxy->nvectors);
-        proxy->nvectors = 0;
+    if (proxy->nvectors) {
+        if (modern && modern_mem_bar == 0) {
+            if (msix_init(&proxy->pci_dev, proxy->nvectors,
+                          &proxy->modern_bar, modern_mem_bar,
+                          modern_mem_size - 0x2000,
+                          &proxy->modern_bar, modern_mem_bar,
+                          modern_mem_size - 0x1000,
+                          0x90)) {
+                error_report("unable to init msix vectors to %" PRIu32,
+                             proxy->nvectors);
+                proxy->nvectors = 0;
+            }
+        } else {
+            if (msix_init_exclusive_bar(&proxy->pci_dev, proxy->nvectors, 1)) {
+                error_report("unable to init msix vectors to %" PRIu32,
+                             proxy->nvectors);
+                proxy->nvectors = 0;
+            }
+        }
     }
 
     proxy->pci_dev.config_write = virtio_write_config;
 
     if (legacy) {
-        size = VIRTIO_PCI_REGION_SIZE(&proxy->pci_dev)
+        legacy_io_size = VIRTIO_PCI_REGION_SIZE(&proxy->pci_dev)
             + virtio_bus_get_vdev_config_len(bus);
-        if (size & (size - 1)) {
-            size = 1 << qemu_fls(size);
+        if (legacy_io_size & (legacy_io_size - 1)) {
+            legacy_io_size = 1 << qemu_fls(legacy_io_size);
         }
 
         memory_region_init_io(&proxy->bar, OBJECT(proxy),
                               &virtio_pci_config_ops,
-                              proxy, "virtio-pci", size);
+                              proxy, "virtio-pci", legacy_io_size);
 
         pci_register_bar(&proxy->pci_dev, 0, PCI_BASE_ADDRESS_SPACE_IO,
                          &proxy->bar);
-- 
1.8.3.1