vfio: Add an option to get migration data size

Add an option to get migration data size by introducing a new migration
feature named VFIO_DEVICE_FEATURE_MIG_DATA_SIZE.

Upon VFIO_DEVICE_FEATURE_GET the estimated data length that will be
required to complete STOP_COPY is returned.

This option may better enable user space to consider before moving to
STOP_COPY whether it can meet the downtime SLA based on the returned
data.

The patch also includes the implementation for mlx5 and hisi for this
new option to make it feature complete for the existing drivers in this
area.

Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Longfang Liu <liulongfang@huawei.com>
Link: https://lore.kernel.org/r/20221106174630.25909-2-yishaih@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
index 39eeca18a0f7c884a18827fbe6d4ccf2584920b9..0c0c0c7f05215e7811007b53e13ea1064510958c 100644 (file)
--- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
+++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
@@ -957,6 +957,14 @@ hisi_acc_vfio_pci_set_device_state(struct vfio_device *vdev,
        return res;
 }
 
+static int
+hisi_acc_vfio_pci_get_data_size(struct vfio_device *vdev,
+                               unsigned long *stop_copy_length)
+{
+       *stop_copy_length = sizeof(struct acc_vf_data);
+       return 0;
+}
+
 static int
 hisi_acc_vfio_pci_get_device_state(struct vfio_device *vdev,
                                   enum vfio_device_mig_state *curr_state)
@@ -1213,6 +1221,7 @@ static void hisi_acc_vfio_pci_close_device(struct vfio_device *core_vdev)
 static const struct vfio_migration_ops hisi_acc_vfio_pci_migrn_state_ops = {
        .migration_set_state = hisi_acc_vfio_pci_set_device_state,
        .migration_get_state = hisi_acc_vfio_pci_get_device_state,
+       .migration_get_data_size = hisi_acc_vfio_pci_get_data_size,
 };
 
 static int hisi_acc_vfio_pci_migrn_init_dev(struct vfio_device *core_vdev)

diff --git a/drivers/vfio/pci/mlx5/main.c b/drivers/vfio/pci/mlx5/main.c
index 457138b92f1347f7310c2d2c0eae6028c19b262c..6e9cf2aacc5279bf2ed05fa27d18987ed6a509ec 100644 (file)
--- a/drivers/vfio/pci/mlx5/main.c
+++ b/drivers/vfio/pci/mlx5/main.c
@@ -512,6 +512,23 @@ mlx5vf_pci_set_device_state(struct vfio_device *vdev,
        return res;
 }
 
+static int mlx5vf_pci_get_data_size(struct vfio_device *vdev,
+                                   unsigned long *stop_copy_length)
+{
+       struct mlx5vf_pci_core_device *mvdev = container_of(
+               vdev, struct mlx5vf_pci_core_device, core_device.vdev);
+       size_t state_size;
+       int ret;
+
+       mutex_lock(&mvdev->state_mutex);
+       ret = mlx5vf_cmd_query_vhca_migration_state(mvdev,
+                                                   &state_size);
+       if (!ret)
+               *stop_copy_length = state_size;
+       mlx5vf_state_mutex_unlock(mvdev);
+       return ret;
+}
+
 static int mlx5vf_pci_get_device_state(struct vfio_device *vdev,
                                       enum vfio_device_mig_state *curr_state)
 {
@@ -577,6 +594,7 @@ static void mlx5vf_pci_close_device(struct vfio_device *core_vdev)
 static const struct vfio_migration_ops mlx5vf_pci_mig_ops = {
        .migration_set_state = mlx5vf_pci_set_device_state,
        .migration_get_state = mlx5vf_pci_get_device_state,
+       .migration_get_data_size = mlx5vf_pci_get_data_size,
 };
 
 static const struct vfio_log_ops mlx5vf_pci_log_ops = {

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 9be2d5be5d959cb53bf3acbd2aaabaaf58103b66..189d4930c276d81ce84f717427cb84dfa7402e4b 100644 (file)
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -2127,7 +2127,8 @@ int vfio_pci_core_register_device(struct vfio_pci_core_device *vdev)
 
        if (vdev->vdev.mig_ops) {
                if (!(vdev->vdev.mig_ops->migration_get_state &&
-                     vdev->vdev.mig_ops->migration_set_state) ||
+                     vdev->vdev.mig_ops->migration_set_state &&
+                     vdev->vdev.mig_ops->migration_get_data_size) ||
                    !(vdev->vdev.migration_flags & VFIO_MIGRATION_STOP_COPY))
                        return -EINVAL;
        }

diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 9835757e2bee40dcac858aba11e8f1a21739d10e..662e267a3e13deeed3456aef54d9d008b4d5a1ee 100644 (file)
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -1242,6 +1242,34 @@ out_copy:
        return 0;
 }
 
+static int
+vfio_ioctl_device_feature_migration_data_size(struct vfio_device *device,
+                                             u32 flags, void __user *arg,
+                                             size_t argsz)
+{
+       struct vfio_device_feature_mig_data_size data_size = {};
+       unsigned long stop_copy_length;
+       int ret;
+
+       if (!device->mig_ops)
+               return -ENOTTY;
+
+       ret = vfio_check_feature(flags, argsz, VFIO_DEVICE_FEATURE_GET,
+                                sizeof(data_size));
+       if (ret != 1)
+               return ret;
+
+       ret = device->mig_ops->migration_get_data_size(device, &stop_copy_length);
+       if (ret)
+               return ret;
+
+       data_size.stop_copy_length = stop_copy_length;
+       if (copy_to_user(arg, &data_size, sizeof(data_size)))
+               return -EFAULT;
+
+       return 0;
+}
+
 static int vfio_ioctl_device_feature_migration(struct vfio_device *device,
                                               u32 flags, void __user *arg,
                                               size_t argsz)
@@ -1469,6 +1497,10 @@ static int vfio_ioctl_device_feature(struct vfio_device *device,
                return vfio_ioctl_device_feature_logging_report(
                        device, feature.flags, arg->data,
                        feature.argsz - minsz);
+       case VFIO_DEVICE_FEATURE_MIG_DATA_SIZE:
+               return vfio_ioctl_device_feature_migration_data_size(
+                       device, feature.flags, arg->data,
+                       feature.argsz - minsz);
        default:
                if (unlikely(!device->ops->device_feature))
                        return -EINVAL;

diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index e7480154825ece86fdd6769100538ea4df23cb98..43b67e46a2cb50fdff3de38597a15755138224a7 100644 (file)
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -107,6 +107,9 @@ struct vfio_device_ops {
  * @migration_get_state: Optional callback to get the migration state for
  *         devices that support migration. It's mandatory for
  *         VFIO_DEVICE_FEATURE_MIGRATION migration support.
+ * @migration_get_data_size: Optional callback to get the estimated data
+ *          length that will be required to complete stop copy. It's mandatory for
+ *          VFIO_DEVICE_FEATURE_MIGRATION migration support.
  */
 struct vfio_migration_ops {
        struct file *(*migration_set_state)(
@@ -114,6 +117,8 @@ struct vfio_migration_ops {
                enum vfio_device_mig_state new_state);
        int (*migration_get_state)(struct vfio_device *device,
                                   enum vfio_device_mig_state *curr_state);
+       int (*migration_get_data_size)(struct vfio_device *device,
+                                      unsigned long *stop_copy_length);
 };
 
 /**

diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index d7d8e0922376cce4cf4893fee9d4939aa90d1e9e..3e45dbaf190ef528275bd3b0ea1d94036981cdc2 100644 (file)
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -1128,6 +1128,19 @@ struct vfio_device_feature_dma_logging_report {
 
 #define VFIO_DEVICE_FEATURE_DMA_LOGGING_REPORT 8
 
+/*
+ * Upon VFIO_DEVICE_FEATURE_GET read back the estimated data length that will
+ * be required to complete stop copy.
+ *
+ * Note: Can be called on each device state.
+ */
+
+struct vfio_device_feature_mig_data_size {
+       __aligned_u64 stop_copy_length;
+};
+
+#define VFIO_DEVICE_FEATURE_MIG_DATA_SIZE 9
+
 /* -------- API for Type1 VFIO IOMMU -------- */
 
 /**