From 0dce165b1adf8d7f67030bb257e00107db8022de Mon Sep 17 00:00:00 2001 From: Yishai Hadas Date: Tue, 6 Dec 2022 10:34:34 +0200 Subject: [PATCH] vfio/mlx5: Introduce vfio precopy ioctl implementation vfio precopy ioctl returns an estimation of data available for transferring from the device. Whenever a user is using VFIO_MIG_GET_PRECOPY_INFO, track the current state of the device, and if needed, append the dirty data to the transfer FD data. This is done by saving a middle state. As mlx5 runs the SAVE command asynchronously, make sure to query for incremental data only once there is no active save command. Running both in parallel, might end-up with a failure in the incremental query command on un-tracked vhca. Also, a middle state will be saved only after the previous state has finished its SAVE command and has been fully transferred, this prevents endless use resources. Co-developed-by: Shay Drory Signed-off-by: Shay Drory Reviewed-by: Jason Gunthorpe Signed-off-by: Yishai Hadas Link: https://lore.kernel.org/r/20221206083438.37807-11-yishaih@nvidia.com Signed-off-by: Alex Williamson --- drivers/vfio/pci/mlx5/cmd.c | 16 +++++ drivers/vfio/pci/mlx5/main.c | 111 +++++++++++++++++++++++++++++++++++ 2 files changed, 127 insertions(+) diff --git a/drivers/vfio/pci/mlx5/cmd.c b/drivers/vfio/pci/mlx5/cmd.c index 160fa38fc78d..12e74ecebe64 100644 --- a/drivers/vfio/pci/mlx5/cmd.c +++ b/drivers/vfio/pci/mlx5/cmd.c @@ -67,12 +67,25 @@ int mlx5vf_cmd_query_vhca_migration_state(struct mlx5vf_pci_core_device *mvdev, { u32 out[MLX5_ST_SZ_DW(query_vhca_migration_state_out)] = {}; u32 in[MLX5_ST_SZ_DW(query_vhca_migration_state_in)] = {}; + bool inc = query_flags & MLX5VF_QUERY_INC; int ret; lockdep_assert_held(&mvdev->state_mutex); if (mvdev->mdev_detach) return -ENOTCONN; + /* + * In case PRE_COPY is used, saving_migf is exposed while device is + * running. Make sure to run only once there is no active save command. + * Running both in parallel, might end-up with a failure in the + * incremental query command on un-tracked vhca. + */ + if (inc) { + ret = wait_for_completion_interruptible(&mvdev->saving_migf->save_comp); + if (ret) + return ret; + } + MLX5_SET(query_vhca_migration_state_in, in, opcode, MLX5_CMD_OP_QUERY_VHCA_MIGRATION_STATE); MLX5_SET(query_vhca_migration_state_in, in, vhca_id, mvdev->vhca_id); @@ -82,6 +95,9 @@ int mlx5vf_cmd_query_vhca_migration_state(struct mlx5vf_pci_core_device *mvdev, ret = mlx5_cmd_exec_inout(mvdev->mdev, query_vhca_migration_state, in, out); + if (inc) + complete(&mvdev->saving_migf->save_comp); + if (ret) return ret; diff --git a/drivers/vfio/pci/mlx5/main.c b/drivers/vfio/pci/mlx5/main.c index 9a36e36ec33b..2c8ac763057c 100644 --- a/drivers/vfio/pci/mlx5/main.c +++ b/drivers/vfio/pci/mlx5/main.c @@ -294,10 +294,121 @@ static void mlx5vf_mark_err(struct mlx5_vf_migration_file *migf) wake_up_interruptible(&migf->poll_wait); } +static long mlx5vf_precopy_ioctl(struct file *filp, unsigned int cmd, + unsigned long arg) +{ + struct mlx5_vf_migration_file *migf = filp->private_data; + struct mlx5vf_pci_core_device *mvdev = migf->mvdev; + struct mlx5_vhca_data_buffer *buf; + struct vfio_precopy_info info = {}; + loff_t *pos = &filp->f_pos; + unsigned long minsz; + size_t inc_length = 0; + bool end_of_data; + int ret; + + if (cmd != VFIO_MIG_GET_PRECOPY_INFO) + return -ENOTTY; + + minsz = offsetofend(struct vfio_precopy_info, dirty_bytes); + + if (copy_from_user(&info, (void __user *)arg, minsz)) + return -EFAULT; + + if (info.argsz < minsz) + return -EINVAL; + + mutex_lock(&mvdev->state_mutex); + if (mvdev->mig_state != VFIO_DEVICE_STATE_PRE_COPY && + mvdev->mig_state != VFIO_DEVICE_STATE_PRE_COPY_P2P) { + ret = -EINVAL; + goto err_state_unlock; + } + + /* + * We can't issue a SAVE command when the device is suspended, so as + * part of VFIO_DEVICE_STATE_PRE_COPY_P2P no reason to query for extra + * bytes that can't be read. + */ + if (mvdev->mig_state == VFIO_DEVICE_STATE_PRE_COPY) { + /* + * Once the query returns it's guaranteed that there is no + * active SAVE command. + * As so, the other code below is safe with the proper locks. + */ + ret = mlx5vf_cmd_query_vhca_migration_state(mvdev, &inc_length, + MLX5VF_QUERY_INC); + if (ret) + goto err_state_unlock; + } + + mutex_lock(&migf->lock); + if (migf->state == MLX5_MIGF_STATE_ERROR) { + ret = -ENODEV; + goto err_migf_unlock; + } + + buf = mlx5vf_get_data_buff_from_pos(migf, *pos, &end_of_data); + if (buf) { + if (buf->start_pos == 0) { + info.initial_bytes = buf->header_image_size - *pos; + } else if (buf->start_pos == + sizeof(struct mlx5_vf_migration_header)) { + /* First data buffer following the header */ + info.initial_bytes = buf->start_pos + + buf->length - *pos; + } else { + info.dirty_bytes = buf->start_pos + buf->length - *pos; + } + } else { + if (!end_of_data) { + ret = -EINVAL; + goto err_migf_unlock; + } + + info.dirty_bytes = inc_length; + } + + if (!end_of_data || !inc_length) { + mutex_unlock(&migf->lock); + goto done; + } + + mutex_unlock(&migf->lock); + /* + * We finished transferring the current state and the device has a + * dirty state, save a new state to be ready for. + */ + buf = mlx5vf_get_data_buffer(migf, inc_length, DMA_FROM_DEVICE); + if (IS_ERR(buf)) { + ret = PTR_ERR(buf); + mlx5vf_mark_err(migf); + goto err_state_unlock; + } + + ret = mlx5vf_cmd_save_vhca_state(mvdev, migf, buf, true, true); + if (ret) { + mlx5vf_mark_err(migf); + mlx5vf_put_data_buffer(buf); + goto err_state_unlock; + } + +done: + mlx5vf_state_mutex_unlock(mvdev); + return copy_to_user((void __user *)arg, &info, minsz); +err_migf_unlock: + mutex_unlock(&migf->lock); +err_state_unlock: + mlx5vf_state_mutex_unlock(mvdev); + return ret; +} + static const struct file_operations mlx5vf_save_fops = { .owner = THIS_MODULE, .read = mlx5vf_save_read, .poll = mlx5vf_save_poll, + .unlocked_ioctl = mlx5vf_precopy_ioctl, + .compat_ioctl = compat_ptr_ioctl, .release = mlx5vf_release_file, .llseek = no_llseek, };