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Date: Wed, 4 May 2022 14:34:31 -0600
From: Alex Williamson <alex.williamson@...hat.com>
To: Yishai Hadas <yishaih@...dia.com>
Cc: <jgg@...dia.com>, <saeedm@...dia.com>, <kvm@...r.kernel.org>,
<netdev@...r.kernel.org>, <kuba@...nel.org>, <leonro@...dia.com>,
<maorg@...dia.com>, <cohuck@...hat.com>
Subject: Re: [PATCH mlx5-next 3/5] vfio/mlx5: Manage the VF attach/detach
callback from the PF
On Wed, 27 Apr 2022 12:31:18 +0300
Yishai Hadas <yishaih@...dia.com> wrote:
> Manage the VF attach/detach callback from the PF.
>
> This lets the driver to enable parallel VFs migration as will be
> introduced in the next patch.
>
> Signed-off-by: Yishai Hadas <yishaih@...dia.com>
> Signed-off-by: Leon Romanovsky <leonro@...dia.com>
> ---
> drivers/vfio/pci/mlx5/cmd.c | 59 +++++++++++++++++++++++++++++++++---
> drivers/vfio/pci/mlx5/cmd.h | 23 +++++++++++++-
> drivers/vfio/pci/mlx5/main.c | 25 ++++-----------
> 3 files changed, 82 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/vfio/pci/mlx5/cmd.c b/drivers/vfio/pci/mlx5/cmd.c
> index d608b8167f58..1f84d7b9b9e5 100644
> --- a/drivers/vfio/pci/mlx5/cmd.c
> +++ b/drivers/vfio/pci/mlx5/cmd.c
> @@ -71,21 +71,70 @@ int mlx5vf_cmd_query_vhca_migration_state(struct pci_dev *pdev, u16 vhca_id,
> return ret;
> }
>
> -bool mlx5vf_cmd_is_migratable(struct pci_dev *pdev)
> +static int mlx5fv_vf_event(struct notifier_block *nb,
> + unsigned long event, void *data)
> {
> - struct mlx5_core_dev *mdev = mlx5_vf_get_core_dev(pdev);
> + struct mlx5vf_pci_core_device *mvdev =
> + container_of(nb, struct mlx5vf_pci_core_device, nb);
> +
> + mutex_lock(&mvdev->state_mutex);
> + switch (event) {
> + case MLX5_PF_NOTIFY_ENABLE_VF:
> + mvdev->mdev_detach = false;
> + break;
> + case MLX5_PF_NOTIFY_DISABLE_VF:
> + mvdev->mdev_detach = true;
> + break;
> + default:
> + break;
> + }
> + mlx5vf_state_mutex_unlock(mvdev);
> + return 0;
> +}
> +
> +void mlx5vf_cmd_remove_migratable(struct mlx5vf_pci_core_device *mvdev)
> +{
> + mlx5_sriov_blocking_notifier_unregister(mvdev->mdev, mvdev->vf_id,
> + &mvdev->nb);
> +}
> +
> +bool mlx5vf_cmd_is_migratable(struct mlx5vf_pci_core_device *mvdev)
Why did the original implementation take a pdev knowing we're going to
gut it in the next patch to use an mvdev? The diff would be easier to
read.
There's also quite a lot of setup here now, it's no longer a simple
test whether the device supports migration which makes the name
misleading. This looks like a "setup migration" function that should
return 0/-errno.
> +{
> + struct pci_dev *pdev = mvdev->core_device.pdev;
> bool migratable = false;
> + int ret;
>
> - if (!mdev)
> + mvdev->mdev = mlx5_vf_get_core_dev(pdev);
> + if (!mvdev->mdev)
> return false;
> + if (!MLX5_CAP_GEN(mvdev->mdev, migration))
> + goto end;
> + mvdev->vf_id = pci_iov_vf_id(pdev);
> + if (mvdev->vf_id < 0)
> + goto end;
>
> - if (!MLX5_CAP_GEN(mdev, migration))
> + mutex_init(&mvdev->state_mutex);
> + spin_lock_init(&mvdev->reset_lock);
> + mvdev->nb.notifier_call = mlx5fv_vf_event;
> + ret = mlx5_sriov_blocking_notifier_register(mvdev->mdev, mvdev->vf_id,
> + &mvdev->nb);
> + if (ret)
> goto end;
>
> + mutex_lock(&mvdev->state_mutex);
> + if (mvdev->mdev_detach)
> + goto unreg;
> +
> + mlx5vf_state_mutex_unlock(mvdev);
> migratable = true;
> + goto end;
>
> +unreg:
> + mlx5vf_state_mutex_unlock(mvdev);
> + mlx5_sriov_blocking_notifier_unregister(mvdev->mdev, mvdev->vf_id,
> + &mvdev->nb);
> end:
> - mlx5_vf_put_core_dev(mdev);
> + mlx5_vf_put_core_dev(mvdev->mdev);
> return migratable;
> }
>
> diff --git a/drivers/vfio/pci/mlx5/cmd.h b/drivers/vfio/pci/mlx5/cmd.h
> index 2da6a1c0ec5c..f47174eab4b8 100644
> --- a/drivers/vfio/pci/mlx5/cmd.h
> +++ b/drivers/vfio/pci/mlx5/cmd.h
> @@ -7,6 +7,7 @@
> #define MLX5_VFIO_CMD_H
>
> #include <linux/kernel.h>
> +#include <linux/vfio_pci_core.h>
> #include <linux/mlx5/driver.h>
>
> struct mlx5_vf_migration_file {
> @@ -24,14 +25,34 @@ struct mlx5_vf_migration_file {
> unsigned long last_offset;
> };
>
> +struct mlx5vf_pci_core_device {
> + struct vfio_pci_core_device core_device;
> + int vf_id;
> + u16 vhca_id;
> + u8 migrate_cap:1;
> + u8 deferred_reset:1;
> + /* protect migration state */
> + struct mutex state_mutex;
> + enum vfio_device_mig_state mig_state;
> + /* protect the reset_done flow */
> + spinlock_t reset_lock;
> + struct mlx5_vf_migration_file *resuming_migf;
> + struct mlx5_vf_migration_file *saving_migf;
> + struct notifier_block nb;
> + struct mlx5_core_dev *mdev;
> + u8 mdev_detach:1;
> +};
> +
> int mlx5vf_cmd_suspend_vhca(struct pci_dev *pdev, u16 vhca_id, u16 op_mod);
> int mlx5vf_cmd_resume_vhca(struct pci_dev *pdev, u16 vhca_id, u16 op_mod);
> int mlx5vf_cmd_query_vhca_migration_state(struct pci_dev *pdev, u16 vhca_id,
> size_t *state_size);
> int mlx5vf_cmd_get_vhca_id(struct pci_dev *pdev, u16 function_id, u16 *vhca_id);
> -bool mlx5vf_cmd_is_migratable(struct pci_dev *pdev);
> +bool mlx5vf_cmd_is_migratable(struct mlx5vf_pci_core_device *mvdev);
> +void mlx5vf_cmd_remove_migratable(struct mlx5vf_pci_core_device *mvdev);
> int mlx5vf_cmd_save_vhca_state(struct pci_dev *pdev, u16 vhca_id,
> struct mlx5_vf_migration_file *migf);
> int mlx5vf_cmd_load_vhca_state(struct pci_dev *pdev, u16 vhca_id,
> struct mlx5_vf_migration_file *migf);
> +void mlx5vf_state_mutex_unlock(struct mlx5vf_pci_core_device *mvdev);
> #endif /* MLX5_VFIO_CMD_H */
> diff --git a/drivers/vfio/pci/mlx5/main.c b/drivers/vfio/pci/mlx5/main.c
> index 2578f61eaeae..445c516d38d9 100644
> --- a/drivers/vfio/pci/mlx5/main.c
> +++ b/drivers/vfio/pci/mlx5/main.c
> @@ -17,7 +17,6 @@
> #include <linux/uaccess.h>
> #include <linux/vfio.h>
> #include <linux/sched/mm.h>
> -#include <linux/vfio_pci_core.h>
> #include <linux/anon_inodes.h>
>
> #include "cmd.h"
> @@ -25,20 +24,6 @@
> /* Arbitrary to prevent userspace from consuming endless memory */
> #define MAX_MIGRATION_SIZE (512*1024*1024)
>
> -struct mlx5vf_pci_core_device {
> - struct vfio_pci_core_device core_device;
> - u16 vhca_id;
> - u8 migrate_cap:1;
> - u8 deferred_reset:1;
> - /* protect migration state */
> - struct mutex state_mutex;
> - enum vfio_device_mig_state mig_state;
> - /* protect the reset_done flow */
> - spinlock_t reset_lock;
> - struct mlx5_vf_migration_file *resuming_migf;
> - struct mlx5_vf_migration_file *saving_migf;
> -};
> -
> static struct page *
> mlx5vf_get_migration_page(struct mlx5_vf_migration_file *migf,
> unsigned long offset)
> @@ -444,7 +429,7 @@ mlx5vf_pci_step_device_state_locked(struct mlx5vf_pci_core_device *mvdev,
> * This function is called in all state_mutex unlock cases to
> * handle a 'deferred_reset' if exists.
> */
> -static void mlx5vf_state_mutex_unlock(struct mlx5vf_pci_core_device *mvdev)
> +void mlx5vf_state_mutex_unlock(struct mlx5vf_pci_core_device *mvdev)
> {
> again:
> spin_lock(&mvdev->reset_lock);
> @@ -597,13 +582,11 @@ static int mlx5vf_pci_probe(struct pci_dev *pdev,
> return -ENOMEM;
> vfio_pci_core_init_device(&mvdev->core_device, pdev, &mlx5vf_pci_ops);
>
> - if (pdev->is_virtfn && mlx5vf_cmd_is_migratable(pdev)) {
> + if (pdev->is_virtfn && mlx5vf_cmd_is_migratable(mvdev)) {
> mvdev->migrate_cap = 1;
> mvdev->core_device.vdev.migration_flags =
> VFIO_MIGRATION_STOP_COPY |
> VFIO_MIGRATION_P2P;
Why do these aspects of setting up migration remain here? Do we even
need this new function to have a return value? It looks like all of
this and testing whether the pdev->is_virtfn could be pushed into the
new function, which could then return void. Thanks,
Alex
> - mutex_init(&mvdev->state_mutex);
> - spin_lock_init(&mvdev->reset_lock);
> }
>
> ret = vfio_pci_core_register_device(&mvdev->core_device);
> @@ -614,6 +597,8 @@ static int mlx5vf_pci_probe(struct pci_dev *pdev,
> return 0;
>
> out_free:
> + if (mvdev->migrate_cap)
> + mlx5vf_cmd_remove_migratable(mvdev);
> vfio_pci_core_uninit_device(&mvdev->core_device);
> kfree(mvdev);
> return ret;
> @@ -624,6 +609,8 @@ static void mlx5vf_pci_remove(struct pci_dev *pdev)
> struct mlx5vf_pci_core_device *mvdev = dev_get_drvdata(&pdev->dev);
>
> vfio_pci_core_unregister_device(&mvdev->core_device);
> + if (mvdev->migrate_cap)
> + mlx5vf_cmd_remove_migratable(mvdev);
> vfio_pci_core_uninit_device(&mvdev->core_device);
> kfree(mvdev);
> }
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