[Qemu-devel] [PATCH 8/8] vfio: Create VFIOAddressSpace objects as needed

[David Gibson <david@gibson.dropbear.id.au>]

So far, VFIO has a notion of different logical DMA address spaces, but
only ever uses one (system memory).  This patch extends this, creating
new VFIOAddressSpace objects as necessary, according to the AddressSpace
reported by the PCI subsystem for this device's DMAs.

This isn't enough yet to support guest side IOMMUs with VFIO, but it does
mean we could now support VFIO devices on, for example, a guest side PCI
host bridge which maps system memory at somewhere other than 0 in PCI
space.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/misc/vfio.c |   36 +++++++++++++++++++++++++++++-------
 1 file changed, 29 insertions(+), 7 deletions(-)

diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
index b1e9220..3850d39 100644
--- a/hw/misc/vfio.c
+++ b/hw/misc/vfio.c
@@ -116,9 +116,10 @@ enum {
 typedef struct VFIOAddressSpace {
     AddressSpace *as;
     QLIST_HEAD(, VFIOContainer) containers;
+    QLIST_ENTRY(VFIOAddressSpace) list;
 } VFIOAddressSpace;
 
-static VFIOAddressSpace vfio_address_space_memory;
+QLIST_HEAD(, VFIOAddressSpace) vfio_address_spaces;
 
 struct VFIOGroup;
 
@@ -2635,6 +2636,23 @@ static void vfio_address_space_init(VFIOAddressSpace *vas, AddressSpace *as)
     QLIST_INIT(&vas->containers);
 }
 
+static VFIOAddressSpace *vfio_address_space_get(AddressSpace *as)
+{
+    VFIOAddressSpace *vas;
+
+    QLIST_FOREACH(vas, &vfio_address_spaces, list) {
+        if (vas->as == as)
+            return vas;
+    }
+
+    /* No suitable VFIOAddressSpace, create a new one */
+    vas = g_malloc0(sizeof(*vas));
+    vfio_address_space_init(vas, as);
+    QLIST_INSERT_HEAD(&vfio_address_spaces, vas, list);
+
+    return vas;
+}
+
 static int vfio_connect(VFIOGroup *group, VFIOAddressSpace *vas)
 {
     VFIOContainer *container;
@@ -2727,6 +2745,8 @@ static void vfio_disconnect(VFIOGroup *group)
     group->container = NULL;
 
     if (QLIST_EMPTY(&container->group_list)) {
+        VFIOAddressSpace *vas = container->vas;
+
         if (container->iommu_data.release) {
             container->iommu_data.release(container);
         }
@@ -2734,6 +2754,11 @@ static void vfio_disconnect(VFIOGroup *group)
         DPRINTF("vfio_disconnect: close container->fd\n");
         close(container->fd);
         g_free(container);
+
+        if (QLIST_EMPTY(&vas->containers)) {
+            QLIST_REMOVE(vas, list);
+            g_free(vas);
+        }
     }
 }
 
@@ -2984,6 +3009,7 @@ static int vfio_initfn(PCIDevice *pdev)
 {
     VFIODevice *pvdev, *vdev = DO_UPCAST(VFIODevice, pdev, pdev);
     VFIOGroup *group;
+    VFIOAddressSpace *vas;
     char path[PATH_MAX], iommu_group_path[PATH_MAX], *group_name;
     ssize_t len;
     struct stat st;
@@ -3019,12 +3045,9 @@ static int vfio_initfn(PCIDevice *pdev)
     DPRINTF("%s(%04x:%02x:%02x.%x) group %d\n", __func__, vdev->host.domain,
             vdev->host.bus, vdev->host.slot, vdev->host.function, groupid);
 
-    if (pci_iommu_as(pdev) != &address_space_memory) {
-        error_report("vfio: DMA address space must be system memory");
-        return -ENXIO;
-    }
+    vas = vfio_address_space_get(pci_iommu_as(pdev));
 
-    group = vfio_get_group(groupid, &vfio_address_space_memory);
+    group = vfio_get_group(groupid, vas);
     if (!group) {
         error_report("vfio: failed to get group %d", groupid);
         return -ENOENT;
@@ -3244,7 +3267,6 @@ static const TypeInfo vfio_pci_dev_info = {
 
 static void register_vfio_pci_dev_type(void)
 {
-    vfio_address_space_init(&vfio_address_space_memory, &address_space_memory);
     type_register_static(&vfio_pci_dev_info);
 }
 
-- 
1.7.10.4