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vfio/mlx5: Enforce a single SAVE command at a time

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Enforce a single SAVE command at a time.

As the SAVE command is an asynchronous one, we must enforce running only
a single command at a time.

This will preserve ordering between multiple calls and protect from
races on the migration file data structure.

This is a must for the next patches from the series where as part of
PRE_COPY we may have multiple images to be saved and multiple SAVE
commands may be issued from different flows.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Link: https://lore.kernel.org/r/20221206083438.37807-4-yishaih@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Yishai Hadas 2022-12-06 10:34:27 +02:00 committed by Alex Williamson
parent 4db52602a6
commit 0e7caa65d7
3 changed files with 14 additions and 0 deletions
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6
drivers/vfio/pci/mlx5/cmd.c
View File

@ -281,6 +281,7 @@ void mlx5vf_mig_file_cleanup_cb(struct work_struct *_work)
dma_unmap_sgtable(mdev->device, &migf->table.sgt, DMA_FROM_DEVICE, 0);
mlx5_core_dealloc_pd(mdev, async_data->pdn);
kvfree(async_data->out);
complete(&migf->save_comp);
fput(migf->filp);
}
@ -321,6 +322,10 @@ int mlx5vf_cmd_save_vhca_state(struct mlx5vf_pci_core_device *mvdev,
return -ENOTCONN;
mdev = mvdev->mdev;
err = wait_for_completion_interruptible(&migf->save_comp);
if (err)
return err;
err = mlx5_core_alloc_pd(mdev, &pdn);
if (err)
return err;
@ -371,6 +376,7 @@ err_create_mkey:
dma_unmap_sgtable(mdev->device, &migf->table.sgt, DMA_FROM_DEVICE, 0);
err_dma_map:
mlx5_core_dealloc_pd(mdev, pdn);
complete(&migf->save_comp);
return err;
}

1
drivers/vfio/pci/mlx5/cmd.h
View File

@ -37,6 +37,7 @@ struct mlx5_vf_migration_file {
unsigned long last_offset;
struct mlx5vf_pci_core_device *mvdev;
wait_queue_head_t poll_wait;
struct completion save_comp;
struct mlx5_async_ctx async_ctx;
struct mlx5vf_async_data async_data;
};

7
drivers/vfio/pci/mlx5/main.c
View File

@ -245,6 +245,13 @@ mlx5vf_pci_save_device_data(struct mlx5vf_pci_core_device *mvdev)
stream_open(migf->filp->f_inode, migf->filp);
mutex_init(&migf->lock);
init_waitqueue_head(&migf->poll_wait);
init_completion(&migf->save_comp);
/*
* save_comp is being used as a binary semaphore built from
* a completion. A normal mutex cannot be used because the lock is
* passed between kernel threads and lockdep can't model this.
*/
complete(&migf->save_comp);
mlx5_cmd_init_async_ctx(mvdev->mdev, &migf->async_ctx);
INIT_WORK(&migf->async_data.work, mlx5vf_mig_file_cleanup_cb);
ret = mlx5vf_cmd_query_vhca_migration_state(mvdev,