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vfio/mlx5: Introduce vfio precopy ioctl implementation

Browse source 
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 <shayd@nvidia.com>
Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Link: https://lore.kernel.org/r/20221206083438.37807-11-yishaih@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Yishai Hadas 2022-12-06 10:34:34 +02:00 committed by Alex Williamson
parent 0c9a38fee8
commit 0dce165b1a
2 changed files with 127 additions and 0 deletions
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16
drivers/vfio/pci/mlx5/cmd.c
View file

@ -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;

111
drivers/vfio/pci/mlx5/main.c
View file

@ -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,
};