[RFC 08/18] vfio/container: Introduce vfio_[attach/detach]_device

[Yi Liu <yi.l.liu@intel.com>]

From: Eric Auger <eric.auger@redhat.com>

We want the VFIO devices to be able to use two different
IOMMU callbacks, the legacy VFIO one and the new iommufd one.

Introduce vfio_[attach/detach]_device which aim at hiding the
underlying IOMMU backend (IOCTLs, datatypes, ...).

Once vfio_attach_device completes, the device is attached
to a security context and its fd can be used. Conversely
When vfio_detach_device completes, the device has been
detached to the security context.

In this patch, only the vfio-pci device gets converted to use
the new API. Subsequent patches will handle other devices.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
 hw/vfio/container.c           | 65 +++++++++++++++++++++++++++++++++++
 hw/vfio/pci.c                 | 50 +++------------------------
 include/hw/vfio/vfio-common.h |  2 ++
 3 files changed, 72 insertions(+), 45 deletions(-)

diff --git a/hw/vfio/container.c b/hw/vfio/container.c
index 79972064d3..c74a3cd4ae 100644
--- a/hw/vfio/container.c
+++ b/hw/vfio/container.c
@@ -1214,6 +1214,71 @@ int vfio_eeh_as_op(AddressSpace *as, uint32_t op)
     return vfio_eeh_container_op(container, op);
 }
 
+static int vfio_device_groupid(VFIODevice *vbasedev, Error **errp)
+{
+    char *tmp, group_path[PATH_MAX], *group_name;
+    int ret, groupid;
+    ssize_t len;
+
+    tmp = g_strdup_printf("%s/iommu_group", vbasedev->sysfsdev);
+    len = readlink(tmp, group_path, sizeof(group_path));
+    g_free(tmp);
+
+    if (len <= 0 || len >= sizeof(group_path)) {
+        ret = len < 0 ? -errno : -ENAMETOOLONG;
+        error_setg_errno(errp, -ret, "no iommu_group found");
+        return ret;
+    }
+
+    group_path[len] = 0;
+
+    group_name = basename(group_path);
+    if (sscanf(group_name, "%d", &groupid) != 1) {
+        error_setg_errno(errp, errno, "failed to read %s", group_path);
+        return -errno;
+    }
+    return groupid;
+}
+
+int vfio_attach_device(VFIODevice *vbasedev, AddressSpace *as, Error **errp)
+{
+    int groupid = vfio_device_groupid(vbasedev, errp);
+    VFIODevice *vbasedev_iter;
+    VFIOGroup *group;
+    int ret;
+
+    if (groupid < 0) {
+        return groupid;
+    }
+
+    trace_vfio_realize(vbasedev->name, groupid);
+    group = vfio_get_group(groupid, as, errp);
+    if (!group) {
+        return -1;
+    }
+
+    QLIST_FOREACH(vbasedev_iter, &group->device_list, next) {
+        if (strcmp(vbasedev_iter->name, vbasedev->name) == 0) {
+            error_setg(errp, "device is already attached");
+            vfio_put_group(group);
+            return -1;
+        }
+    }
+    ret = vfio_get_device(group, vbasedev->name, vbasedev, errp);
+    if (ret) {
+        vfio_put_group(group);
+        return -1;
+    }
+
+    return 0;
+}
+
+void vfio_detach_device(VFIODevice *vbasedev)
+{
+    vfio_put_base_device(vbasedev);
+    vfio_put_group(vbasedev->group);
+}
+
 static void vfio_legacy_container_class_init(ObjectClass *klass,
                                              void *data)
 {
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index a00a485e46..0363f81017 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -2654,10 +2654,9 @@ static void vfio_populate_device(VFIOPCIDevice *vdev, Error **errp)
 
 static void vfio_put_device(VFIOPCIDevice *vdev)
 {
-    g_free(vdev->vbasedev.name);
     g_free(vdev->msix);
 
-    vfio_put_base_device(&vdev->vbasedev);
+    vfio_detach_device(&vdev->vbasedev);
 }
 
 static void vfio_err_notifier_handler(void *opaque)
@@ -2804,13 +2803,9 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
 {
     VFIOPCIDevice *vdev = VFIO_PCI(pdev);
     VFIODevice *vbasedev = &vdev->vbasedev;
-    VFIODevice *vbasedev_iter;
-    VFIOGroup *group;
-    char *tmp, *subsys, group_path[PATH_MAX], *group_name;
+    char *tmp, *subsys;
     Error *err = NULL;
-    ssize_t len;
     struct stat st;
-    int groupid;
     int i, ret;
     bool is_mdev;
 
@@ -2839,39 +2834,6 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     vbasedev->type = VFIO_DEVICE_TYPE_PCI;
     vbasedev->dev = DEVICE(vdev);
 
-    tmp = g_strdup_printf("%s/iommu_group", vbasedev->sysfsdev);
-    len = readlink(tmp, group_path, sizeof(group_path));
-    g_free(tmp);
-
-    if (len <= 0 || len >= sizeof(group_path)) {
-        error_setg_errno(errp, len < 0 ? errno : ENAMETOOLONG,
-                         "no iommu_group found");
-        goto error;
-    }
-
-    group_path[len] = 0;
-
-    group_name = basename(group_path);
-    if (sscanf(group_name, "%d", &groupid) != 1) {
-        error_setg_errno(errp, errno, "failed to read %s", group_path);
-        goto error;
-    }
-
-    trace_vfio_realize(vbasedev->name, groupid);
-
-    group = vfio_get_group(groupid, pci_device_iommu_address_space(pdev), errp);
-    if (!group) {
-        goto error;
-    }
-
-    QLIST_FOREACH(vbasedev_iter, &group->device_list, next) {
-        if (strcmp(vbasedev_iter->name, vbasedev->name) == 0) {
-            error_setg(errp, "device is already attached");
-            vfio_put_group(group);
-            goto error;
-        }
-    }
-
     /*
      * Mediated devices *might* operate compatibly with discarding of RAM, but
      * we cannot know for certain, it depends on whether the mdev vendor driver
@@ -2889,13 +2851,12 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     if (vbasedev->ram_block_discard_allowed && !is_mdev) {
         error_setg(errp, "x-balloon-allowed only potentially compatible "
                    "with mdev devices");
-        vfio_put_group(group);
         goto error;
     }
 
-    ret = vfio_get_device(group, vbasedev->name, vbasedev, errp);
+    ret = vfio_attach_device(vbasedev,
+                             pci_device_iommu_address_space(pdev), errp);
     if (ret) {
-        vfio_put_group(group);
         goto error;
     }
 
@@ -3124,12 +3085,12 @@ out_teardown:
     vfio_bars_exit(vdev);
 error:
     error_prepend(errp, VFIO_MSG_PREFIX, vbasedev->name);
+    vfio_detach_device(vbasedev);
 }
 
 static void vfio_instance_finalize(Object *obj)
 {
     VFIOPCIDevice *vdev = VFIO_PCI(obj);
-    VFIOGroup *group = vdev->vbasedev.group;
 
     vfio_display_finalize(vdev);
     vfio_bars_finalize(vdev);
@@ -3143,7 +3104,6 @@ static void vfio_instance_finalize(Object *obj)
      * g_free(vdev->igd_opregion);
      */
     vfio_put_device(vdev);
-    vfio_put_group(group);
 }
 
 static void vfio_exitfn(PCIDevice *pdev)
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 02a6f36a9e..978b2c2f6e 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -180,6 +180,8 @@ VFIOGroup *vfio_get_group(int groupid, AddressSpace *as, Error **errp);
 void vfio_put_group(VFIOGroup *group);
 int vfio_get_device(VFIOGroup *group, const char *name,
                     VFIODevice *vbasedev, Error **errp);
+int vfio_attach_device(VFIODevice *vbasedev, AddressSpace *as, Error **errp);
+void vfio_detach_device(VFIODevice *vbasedev);
 
 extern const MemoryRegionOps vfio_region_ops;
 typedef QLIST_HEAD(VFIOGroupList, VFIOGroup) VFIOGroupList;
-- 
2.27.0