[Qemu-devel] [PATCH 4/8] vfio: Create VFIOAddressSpace objects as needed

[Alexey Kardashevskiy <aik@ozlabs.ru>]

From: 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 | 42 ++++++++++++++++++++++++++++++++++--------
 1 file changed, 34 insertions(+), 8 deletions(-)

diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
index bcd67a0..e1ee56e 100644
--- a/hw/misc/vfio.c
+++ b/hw/misc/vfio.c
@@ -133,9 +133,10 @@ 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;
 
@@ -2609,10 +2610,33 @@ static int vfio_load_rom(VFIODevice *vdev)
     return 0;
 }
 
-static void vfio_address_space_init(VFIOAddressSpace *space, AddressSpace *as)
+static VFIOAddressSpace *vfio_get_address_space(AddressSpace *as)
 {
+    VFIOAddressSpace *space;
+
+    QLIST_FOREACH(space, &vfio_address_spaces, list) {
+        if (space->as == as)
+            return space;
+    }
+
+    /* No suitable VFIOAddressSpace, create a new one */
+    space = g_malloc0(sizeof(*space));
     space->as = as;
     QLIST_INIT(&space->containers);
+
+    QLIST_INSERT_HEAD(&vfio_address_spaces, space, list);
+
+    return space;
+}
+
+static void vfio_put_address_space(VFIOAddressSpace *space)
+{
+    if (!QLIST_EMPTY(&space->containers)) {
+        return;
+    }
+
+    QLIST_REMOVE(space, list);
+    g_free(space);
 }
 
 static int vfio_connect_container(VFIOGroup *group, VFIOAddressSpace *space)
@@ -2707,6 +2731,8 @@ static void vfio_disconnect_container(VFIOGroup *group)
     group->container = NULL;
 
     if (QLIST_EMPTY(&container->group_list)) {
+        VFIOAddressSpace *space = container->space;
+
         if (container->iommu_data.release) {
             container->iommu_data.release(container);
         }
@@ -2714,6 +2740,8 @@ static void vfio_disconnect_container(VFIOGroup *group)
         DPRINTF("vfio_disconnect_container: close container->fd\n");
         close(container->fd);
         g_free(container);
+
+        vfio_put_address_space(space);
     }
 }
 
@@ -3085,6 +3113,7 @@ static int vfio_initfn(PCIDevice *pdev)
 {
     VFIODevice *pvdev, *vdev = DO_UPCAST(VFIODevice, pdev, pdev);
     VFIOGroup *group;
+    VFIOAddressSpace *space;
     char path[PATH_MAX], iommu_group_path[PATH_MAX], *group_name;
     ssize_t len;
     struct stat st;
@@ -3120,14 +3149,12 @@ 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;
-    }
+    space = vfio_get_address_space(pci_iommu_as(pdev));
 
-    group = vfio_get_group(groupid, &vfio_address_space_memory);
+    group = vfio_get_group(groupid, space);
     if (!group) {
         error_report("vfio: failed to get group %d", groupid);
+        vfio_put_address_space(space);
         return -ENOENT;
     }
 
@@ -3348,7 +3375,6 @@ 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);
 }
 
-- 
1.8.3.2