vfio/pci: Introduce vfio_[attach/detach]_device

We want the VFIO devices to be able to use two different
IOMMU backends, 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 from the security context.

At the moment only the implementation based on the legacy
container/group exists. Let's use it from the vfio-pci device.
Subsequent patches will handle other devices.

We also take benefit of this patch to properly free
vbasedev->name on failure.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>

hw/vfio/common.c

@@ -2611,3 +2611,77 @@ 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;
+}
+
+/*
+ * vfio_attach_device: attach a device to a security context
+ * @name and @vbasedev->name are likely to be different depending
+ * on the type of the device, hence the need for passing @name
+ */
+int vfio_attach_device(char *name, 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_attach_device(vbasedev->name, groupid);
+
+    group = vfio_get_group(groupid, as, errp);
+    if (!group) {
+        return -ENOENT;
+    }
+
+    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 -EBUSY;
+        }
+    }
+    ret = vfio_get_device(group, name, vbasedev, errp);
+    if (ret) {
+        vfio_put_group(group);
+    }
+
+    return ret;
+}
+
+void vfio_detach_device(VFIODevice *vbasedev)
+{
+    VFIOGroup *group = vbasedev->group;
+
+    trace_vfio_detach_device(vbasedev->name, group->groupid);
+    vfio_put_base_device(vbasedev);
+    vfio_put_group(group);
+}

hw/vfio/pci.c

@@ -2895,10 +2895,10 @@ static void vfio_populate_device(VFIOPCIDevice *vdev, Error **errp)
 
 static void vfio_pci_put_device(VFIOPCIDevice *vdev)
 {
+    vfio_detach_device(&vdev->vbasedev);
+
     g_free(vdev->vbasedev.name);
     g_free(vdev->msix);
-
-    vfio_put_base_device(&vdev->vbasedev);
 }
 
 static void vfio_err_notifier_handler(void *opaque)
@@ -3045,13 +3045,9 @@ 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;
     char uuid[UUID_FMT_LEN];
@@ -3082,39 +3078,6 @@ 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
@@ -3132,7 +3095,6 @@ 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;
     }
 
@@ -3143,17 +3105,17 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
         name = g_strdup(vbasedev->name);
     }
 
-    ret = vfio_get_device(group, name, vbasedev, errp);
+    ret = vfio_attach_device(name, vbasedev,
+                             pci_device_iommu_address_space(pdev), errp);
     g_free(name);
     if (ret) {
-        vfio_put_group(group);
         goto error;
     }
 
     vfio_populate_device(vdev, &err);
     if (err) {
         error_propagate(errp, err);
-        goto error;
+        goto out_detach;
     }
 
     /* Get a copy of config space */
@@ -3163,7 +3125,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     if (ret < (int)MIN(pci_config_size(&vdev->pdev), vdev->config_size)) {
         ret = ret < 0 ? -errno : -EFAULT;
         error_setg_errno(errp, -ret, "failed to read device config space");
-        goto error;
+        goto out_detach;
     }
 
     /* vfio emulates a lot for us, but some bits need extra love */
@@ -3182,7 +3144,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     if (vdev->vendor_id != PCI_ANY_ID) {
         if (vdev->vendor_id >= 0xffff) {
             error_setg(errp, "invalid PCI vendor ID provided");
-            goto error;
+            goto out_detach;
         }
         vfio_add_emulated_word(vdev, PCI_VENDOR_ID, vdev->vendor_id, ~0);
         trace_vfio_pci_emulated_vendor_id(vbasedev->name, vdev->vendor_id);
@@ -3193,7 +3155,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     if (vdev->device_id != PCI_ANY_ID) {
         if (vdev->device_id > 0xffff) {
             error_setg(errp, "invalid PCI device ID provided");
-            goto error;
+            goto out_detach;
         }
         vfio_add_emulated_word(vdev, PCI_DEVICE_ID, vdev->device_id, ~0);
         trace_vfio_pci_emulated_device_id(vbasedev->name, vdev->device_id);
@@ -3204,7 +3166,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     if (vdev->sub_vendor_id != PCI_ANY_ID) {
         if (vdev->sub_vendor_id > 0xffff) {
             error_setg(errp, "invalid PCI subsystem vendor ID provided");
-            goto error;
+            goto out_detach;
         }
         vfio_add_emulated_word(vdev, PCI_SUBSYSTEM_VENDOR_ID,
                                vdev->sub_vendor_id, ~0);
@@ -3215,7 +3177,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     if (vdev->sub_device_id != PCI_ANY_ID) {
         if (vdev->sub_device_id > 0xffff) {
             error_setg(errp, "invalid PCI subsystem device ID provided");
-            goto error;
+            goto out_detach;
         }
         vfio_add_emulated_word(vdev, PCI_SUBSYSTEM_ID, vdev->sub_device_id, ~0);
         trace_vfio_pci_emulated_sub_device_id(vbasedev->name,
@@ -3248,7 +3210,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     vfio_msix_early_setup(vdev, &err);
     if (err) {
         error_propagate(errp, err);
-        goto error;
+        goto out_detach;
     }
 
     vfio_bars_register(vdev);
@@ -3364,6 +3326,8 @@ out_deregister:
 out_teardown:
     vfio_teardown_msi(vdev);
     vfio_bars_exit(vdev);
+out_detach:
+    vfio_detach_device(vbasedev);
 error:
     error_prepend(errp, VFIO_MSG_PREFIX, vbasedev->name);
 }
@@ -3371,7 +3335,6 @@ error:
 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);
@@ -3385,7 +3348,6 @@ static void vfio_instance_finalize(Object *obj)
      * g_free(vdev->igd_opregion);
      */
     vfio_pci_put_device(vdev);
-    vfio_put_group(group);
 }
 
 static void vfio_exitfn(PCIDevice *pdev)

hw/vfio/trace-events

@@ -37,7 +37,8 @@ vfio_pci_hot_reset_dep_devices(int domain, int bus, int slot, int function, int
 vfio_pci_hot_reset_result(const char *name, const char *result) "%s hot reset: %s"
 vfio_populate_device_config(const char *name, unsigned long size, unsigned long offset, unsigned long flags) "Device %s config:\n  size: 0x%lx, offset: 0x%lx, flags: 0x%lx"
 vfio_populate_device_get_irq_info_failure(const char *errstr) "VFIO_DEVICE_GET_IRQ_INFO failure: %s"
-vfio_realize(const char *name, int group_id) " (%s) group %d"
+vfio_attach_device(const char *name, int group_id) " (%s) group %d"
+vfio_detach_device(const char *name, int group_id) " (%s) group %d"
 vfio_mdev(const char *name, bool is_mdev) " (%s) is_mdev %d"
 vfio_add_ext_cap_dropped(const char *name, uint16_t cap, uint16_t offset) "%s 0x%x@0x%x"
 vfio_pci_reset(const char *name) " (%s)"

include/hw/vfio/vfio-common.h

@@ -225,6 +225,9 @@ void vfio_put_group(VFIOGroup *group);
 struct vfio_device_info *vfio_get_device_info(int fd);
 int vfio_get_device(VFIOGroup *group, const char *name,
                     VFIODevice *vbasedev, Error **errp);
+int vfio_attach_device(char *name, VFIODevice *vbasedev,
+                       AddressSpace *as, Error **errp);
+void vfio_detach_device(VFIODevice *vbasedev);
 
 int vfio_kvm_device_add_fd(int fd, Error **errp);
 int vfio_kvm_device_del_fd(int fd, Error **errp);