Re: [PATCH v2 1/3] virtio: update reset callback to return status

[Jason Wang <jasowang@redhat.com>]

在 2021/4/8 下午4:11, Max Gurtovoy 写道:
> The reset device operation, usually is an operation that might fail from
> various reasons. For example, the controller might be in a bad state and
> can't answer to any request. Usually, the paravirt SW based virtio
> devices always succeed in reset operation but this is not the case for
> HW based virtio devices.


I would like to know under what condition that the reset operation may 
fail (except for the case of a bugg guest).


>
> This commit is also a preparation for adding a timeout mechanism for
> resetting virtio devices.
>
> Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
> ---
>
> changes from v1:
>   - update virtio_ccw.c (Cornelia)
>   - update virtio_uml.c
>   - update mlxbf-tmfifo.c


Note that virtio driver may call reset, so you probably need to convert 
them.

Thanks


>
> ---
>   arch/um/drivers/virtio_uml.c             |  4 +++-
>   drivers/platform/mellanox/mlxbf-tmfifo.c |  4 +++-
>   drivers/remoteproc/remoteproc_virtio.c   |  4 +++-
>   drivers/s390/virtio/virtio_ccw.c         |  9 ++++++---
>   drivers/virtio/virtio.c                  | 22 +++++++++++++++-------
>   drivers/virtio/virtio_mmio.c             |  3 ++-
>   drivers/virtio/virtio_pci_legacy.c       |  4 +++-
>   drivers/virtio/virtio_pci_modern.c       |  3 ++-
>   drivers/virtio/virtio_vdpa.c             |  4 +++-
>   include/linux/virtio_config.h            |  5 +++--
>   10 files changed, 43 insertions(+), 19 deletions(-)
>
> diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c
> index 91ddf74ca888..b6e66265ed32 100644
> --- a/arch/um/drivers/virtio_uml.c
> +++ b/arch/um/drivers/virtio_uml.c
> @@ -827,11 +827,13 @@ static void vu_set_status(struct virtio_device *vdev, u8 status)
>   	vu_dev->status = status;
>   }
>   
> -static void vu_reset(struct virtio_device *vdev)
> +static int vu_reset(struct virtio_device *vdev)
>   {
>   	struct virtio_uml_device *vu_dev = to_virtio_uml_device(vdev);
>   
>   	vu_dev->status = 0;
> +
> +	return 0;
>   }
>   
>   static void vu_del_vq(struct virtqueue *vq)
> diff --git a/drivers/platform/mellanox/mlxbf-tmfifo.c b/drivers/platform/mellanox/mlxbf-tmfifo.c
> index bbc4e71a16ff..c192b8ac5d9e 100644
> --- a/drivers/platform/mellanox/mlxbf-tmfifo.c
> +++ b/drivers/platform/mellanox/mlxbf-tmfifo.c
> @@ -980,11 +980,13 @@ static void mlxbf_tmfifo_virtio_set_status(struct virtio_device *vdev,
>   }
>   
>   /* Reset the device. Not much here for now. */
> -static void mlxbf_tmfifo_virtio_reset(struct virtio_device *vdev)
> +static int mlxbf_tmfifo_virtio_reset(struct virtio_device *vdev)
>   {
>   	struct mlxbf_tmfifo_vdev *tm_vdev = mlxbf_vdev_to_tmfifo(vdev);
>   
>   	tm_vdev->status = 0;
> +
> +	return 0;
>   }
>   
>   /* Read the value of a configuration field. */
> diff --git a/drivers/remoteproc/remoteproc_virtio.c b/drivers/remoteproc/remoteproc_virtio.c
> index 0cc617f76068..ca9573c62c3d 100644
> --- a/drivers/remoteproc/remoteproc_virtio.c
> +++ b/drivers/remoteproc/remoteproc_virtio.c
> @@ -191,7 +191,7 @@ static void rproc_virtio_set_status(struct virtio_device *vdev, u8 status)
>   	dev_dbg(&vdev->dev, "status: %d\n", status);
>   }
>   
> -static void rproc_virtio_reset(struct virtio_device *vdev)
> +static int rproc_virtio_reset(struct virtio_device *vdev)
>   {
>   	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
>   	struct fw_rsc_vdev *rsc;
> @@ -200,6 +200,8 @@ static void rproc_virtio_reset(struct virtio_device *vdev)
>   
>   	rsc->status = 0;
>   	dev_dbg(&vdev->dev, "reset !\n");
> +
> +	return 0;
>   }
>   
>   /* provide the vdev features as retrieved from the firmware */
> diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
> index 54e686dca6de..52b32555e746 100644
> --- a/drivers/s390/virtio/virtio_ccw.c
> +++ b/drivers/s390/virtio/virtio_ccw.c
> @@ -732,14 +732,15 @@ static int virtio_ccw_find_vqs(struct virtio_device *vdev, unsigned nvqs,
>   	return ret;
>   }
>   
> -static void virtio_ccw_reset(struct virtio_device *vdev)
> +static int virtio_ccw_reset(struct virtio_device *vdev)
>   {
>   	struct virtio_ccw_device *vcdev = to_vc_device(vdev);
>   	struct ccw1 *ccw;
> +	int ret;
>   
>   	ccw = ccw_device_dma_zalloc(vcdev->cdev, sizeof(*ccw));
>   	if (!ccw)
> -		return;
> +		return -ENOMEM;
>   
>   	/* Zero status bits. */
>   	vcdev->dma_area->status = 0;
> @@ -749,8 +750,10 @@ static void virtio_ccw_reset(struct virtio_device *vdev)
>   	ccw->flags = 0;
>   	ccw->count = 0;
>   	ccw->cda = 0;
> -	ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_RESET);
> +	ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_RESET);
>   	ccw_device_dma_free(vcdev->cdev, ccw, sizeof(*ccw));
> +
> +	return ret;
>   }
>   
>   static u64 virtio_ccw_get_features(struct virtio_device *vdev)
> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> index 4b15c00c0a0a..ddbfd5b5f3bd 100644
> --- a/drivers/virtio/virtio.c
> +++ b/drivers/virtio/virtio.c
> @@ -338,7 +338,7 @@ int register_virtio_device(struct virtio_device *dev)
>   	/* Assign a unique device index and hence name. */
>   	err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
>   	if (err < 0)
> -		goto out;
> +		goto out_err;
>   
>   	dev->index = err;
>   	dev_set_name(&dev->dev, "virtio%u", dev->index);
> @@ -349,7 +349,9 @@ int register_virtio_device(struct virtio_device *dev)
>   
>   	/* We always start by resetting the device, in case a previous
>   	 * driver messed it up.  This also tests that code path a little. */
> -	dev->config->reset(dev);
> +	err = dev->config->reset(dev);
> +	if (err)
> +		goto out_ida;
>   
>   	/* Acknowledge that we've seen the device. */
>   	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
> @@ -362,10 +364,14 @@ int register_virtio_device(struct virtio_device *dev)
>   	 */
>   	err = device_add(&dev->dev);
>   	if (err)
> -		ida_simple_remove(&virtio_index_ida, dev->index);
> -out:
> -	if (err)
> -		virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
> +		goto out_ida;
> +
> +	return 0;
> +
> +out_ida:
> +	ida_simple_remove(&virtio_index_ida, dev->index);
> +out_err:
> +	virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
>   	return err;
>   }
>   EXPORT_SYMBOL_GPL(register_virtio_device);
> @@ -408,7 +414,9 @@ int virtio_device_restore(struct virtio_device *dev)
>   
>   	/* We always start by resetting the device, in case a previous
>   	 * driver messed it up. */
> -	dev->config->reset(dev);
> +	ret = dev->config->reset(dev);
> +	if (ret)
> +		goto err;
>   
>   	/* Acknowledge that we've seen the device. */
>   	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
> diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
> index 56128b9c46eb..12b8f048c48d 100644
> --- a/drivers/virtio/virtio_mmio.c
> +++ b/drivers/virtio/virtio_mmio.c
> @@ -256,12 +256,13 @@ static void vm_set_status(struct virtio_device *vdev, u8 status)
>   	writel(status, vm_dev->base + VIRTIO_MMIO_STATUS);
>   }
>   
> -static void vm_reset(struct virtio_device *vdev)
> +static int vm_reset(struct virtio_device *vdev)
>   {
>   	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
>   
>   	/* 0 status means a reset. */
>   	writel(0, vm_dev->base + VIRTIO_MMIO_STATUS);
> +	return 0;
>   }
>   
>   
> diff --git a/drivers/virtio/virtio_pci_legacy.c b/drivers/virtio/virtio_pci_legacy.c
> index d62e9835aeec..0b5d95e3efa1 100644
> --- a/drivers/virtio/virtio_pci_legacy.c
> +++ b/drivers/virtio/virtio_pci_legacy.c
> @@ -89,7 +89,7 @@ static void vp_set_status(struct virtio_device *vdev, u8 status)
>   	iowrite8(status, vp_dev->ioaddr + VIRTIO_PCI_STATUS);
>   }
>   
> -static void vp_reset(struct virtio_device *vdev)
> +static int vp_reset(struct virtio_device *vdev)
>   {
>   	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
>   	/* 0 status means a reset. */
> @@ -99,6 +99,8 @@ static void vp_reset(struct virtio_device *vdev)
>   	ioread8(vp_dev->ioaddr + VIRTIO_PCI_STATUS);
>   	/* Flush pending VQ/configuration callbacks. */
>   	vp_synchronize_vectors(vdev);
> +
> +	return 0;
>   }
>   
>   static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
> diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> index fbd4ebc00eb6..cc3412a96a17 100644
> --- a/drivers/virtio/virtio_pci_modern.c
> +++ b/drivers/virtio/virtio_pci_modern.c
> @@ -158,7 +158,7 @@ static void vp_set_status(struct virtio_device *vdev, u8 status)
>   	vp_modern_set_status(&vp_dev->mdev, status);
>   }
>   
> -static void vp_reset(struct virtio_device *vdev)
> +static int vp_reset(struct virtio_device *vdev)
>   {
>   	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
>   	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> @@ -174,6 +174,7 @@ static void vp_reset(struct virtio_device *vdev)
>   		msleep(1);
>   	/* Flush pending VQ/configuration callbacks. */
>   	vp_synchronize_vectors(vdev);
> +	return 0;
>   }
>   
>   static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
> diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
> index e28acf482e0c..5fd4e627a9b0 100644
> --- a/drivers/virtio/virtio_vdpa.c
> +++ b/drivers/virtio/virtio_vdpa.c
> @@ -97,11 +97,13 @@ static void virtio_vdpa_set_status(struct virtio_device *vdev, u8 status)
>   	return ops->set_status(vdpa, status);
>   }
>   
> -static void virtio_vdpa_reset(struct virtio_device *vdev)
> +static int virtio_vdpa_reset(struct virtio_device *vdev)
>   {
>   	struct vdpa_device *vdpa = vd_get_vdpa(vdev);
>   
>   	vdpa_reset(vdpa);
> +
> +	return 0;
>   }
>   
>   static bool virtio_vdpa_notify(struct virtqueue *vq)
> diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
> index 8519b3ae5d52..d2b0f1699a75 100644
> --- a/include/linux/virtio_config.h
> +++ b/include/linux/virtio_config.h
> @@ -44,9 +44,10 @@ struct virtio_shm_region {
>    *	status: the new status byte
>    * @reset: reset the device
>    *	vdev: the virtio device
> - *	After this, status and feature negotiation must be done again
> + *	Upon success, status and feature negotiation must be done again
>    *	Device must not be reset from its vq/config callbacks, or in
>    *	parallel with being added/removed.
> + *	Returns 0 on success or error status.
>    * @find_vqs: find virtqueues and instantiate them.
>    *	vdev: the virtio_device
>    *	nvqs: the number of virtqueues to find
> @@ -82,7 +83,7 @@ struct virtio_config_ops {
>   	u32 (*generation)(struct virtio_device *vdev);
>   	u8 (*get_status)(struct virtio_device *vdev);
>   	void (*set_status)(struct virtio_device *vdev, u8 status);
> -	void (*reset)(struct virtio_device *vdev);
> +	int (*reset)(struct virtio_device *vdev);
>   	int (*find_vqs)(struct virtio_device *, unsigned nvqs,
>   			struct virtqueue *vqs[], vq_callback_t *callbacks[],
>   			const char * const names[], const bool *ctx,

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