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

Max Gurtovoy
2021-04-08T09:57:01Z

On 4/8/2021 11:58 AM, Jason Wang wrote:
>
> 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).

The controller might not be ready or stuck. This is a real use case for
many PCI devices.

For real devices the FW might be in a bad state and it can happen also
for paravirt device if you have a bug in the controller code or if you
entered some error flow (Out of memory).

You don't want to be stuck because of one bad device.

>
>
>>
>> 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.

I'm sure I understand.

Convert to what ?

Thanks.

>
> 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,
>