[Qemu-devel] [PATCH RFC 2/9] vfio: No-IOMMU mode support

[Xiao Feng Ren]

Add qemu support for the newly introduced VFIO No-IOMMU driver.

We need to add special handling for:
- Group character device is /dev/vfio/noiommu-$GROUP.
- No-IOMMU does not rely on a memory listener.
- No IOMMU will be set for its group, so no need to call
  vfio_kvm_device_add_group.

Signed-off-by: Xiao Feng Ren <address@hidden>
---
 hw/vfio/common.c              | 66 ++++++++++++++++++++++++++++++++++---------
 include/hw/vfio/vfio-common.h |  2 ++
 2 files changed, 55 insertions(+), 13 deletions(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index f27db36..656c303 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -789,6 +789,33 @@ static int vfio_connect_container(VFIOGroup *group, 
AddressSpace *as)
     container = g_malloc0(sizeof(*container));
     container->space = space;
     container->fd = fd;
+    container->noiommu = group->noiommu;
+
+    if (container->noiommu) {
+        ret = ioctl(group->fd, VFIO_GROUP_SET_CONTAINER, &fd);
+        if (ret) {
+            error_report("vfio: failed to set group container: %m");
+            ret = -errno;
+            goto free_container_exit;
+        }
+
+        ret = ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_NOIOMMU_IOMMU);
+        if (!ret) {
+            error_report("vfio: No available IOMMU models");
+            ret = -EINVAL;
+            goto free_container_exit;
+        }
+
+        ret = ioctl(fd, VFIO_SET_IOMMU, VFIO_NOIOMMU_IOMMU);
+        if (ret) {
+            error_report("vfio: failed to set iommu for container: %m");
+            ret = -errno;
+            goto free_container_exit;
+        }
+
+        goto listener_register;
+    }
+
     if (ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_TYPE1_IOMMU) ||
         ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_TYPE1v2_IOMMU)) {
         bool v2 = !!ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_TYPE1v2_IOMMU);
@@ -878,14 +905,16 @@ static int vfio_connect_container(VFIOGroup *group, 
AddressSpace *as)
         goto free_container_exit;
     }
 
-    container->listener = vfio_memory_listener;
-
-    memory_listener_register(&container->listener, container->space->as);
-
-    if (container->error) {
-        ret = container->error;
-        error_report("vfio: memory listener initialization failed for 
container");
-        goto listener_release_exit;
+listener_register:
+    if (!container->noiommu) {
+        container->listener = vfio_memory_listener;
+        memory_listener_register(&container->listener, container->space->as);
+        if (container->error) {
+            ret = container->error;
+            error_report("vfio: memory listener initialization failed for "
+                         "container");
+            goto listener_release_exit;
+        }
     }
 
     container->initialized = true;
@@ -898,7 +927,9 @@ static int vfio_connect_container(VFIOGroup *group, 
AddressSpace *as)
 
     return 0;
 listener_release_exit:
-    vfio_listener_release(container);
+    if (!container->noiommu) {
+        vfio_listener_release(container);
+    }
 
 free_container_exit:
     g_free(container);
@@ -928,7 +959,9 @@ static void vfio_disconnect_container(VFIOGroup *group)
         VFIOAddressSpace *space = container->space;
         VFIOGuestIOMMU *giommu, *tmp;
 
-        vfio_listener_release(container);
+        if (!container->noiommu) {
+            vfio_listener_release(container);
+        }
         QLIST_REMOVE(container, next);
 
         QLIST_FOREACH_SAFE(giommu, &container->giommu_list, giommu_next, tmp) {
@@ -969,8 +1002,13 @@ VFIOGroup *vfio_get_group(int groupid, AddressSpace *as)
     snprintf(path, sizeof(path), "/dev/vfio/%d", groupid);
     group->fd = qemu_open(path, O_RDWR);
     if (group->fd < 0) {
-        error_report("vfio: error opening %s: %m", path);
-        goto free_group_exit;
+        snprintf(path, sizeof(path), "/dev/vfio/noiommu-%d", groupid);
+        group->fd = qemu_open(path, O_RDWR);
+        if (group->fd < 0) {
+            error_report("vfio: error opening %s: %m", path);
+            goto free_group_exit;
+        }
+        group->noiommu = 1;
     }
 
     if (ioctl(group->fd, VFIO_GROUP_GET_STATUS, &status)) {
@@ -999,7 +1037,9 @@ VFIOGroup *vfio_get_group(int groupid, AddressSpace *as)
 
     QLIST_INSERT_HEAD(&vfio_group_list, group, next);
 
-    vfio_kvm_device_add_group(group);
+    if (!group->noiommu) {
+        vfio_kvm_device_add_group(group);
+    }
 
     return group;
 
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index eb0e1b0..85c2a74 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -72,6 +72,7 @@ struct VFIOGroup;
 typedef struct VFIOContainer {
     VFIOAddressSpace *space;
     int fd; /* /dev/vfio/vfio, empowered by the attached groups */
+    bool noiommu;
     MemoryListener listener;
     int error;
     bool initialized;
@@ -121,6 +122,7 @@ struct VFIODeviceOps {
 typedef struct VFIOGroup {
     int fd;
     int groupid;
+    bool noiommu;
     VFIOContainer *container;
     QLIST_HEAD(, VFIODevice) device_list;
     QLIST_ENTRY(VFIOGroup) next;
-- 
2.6.6