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Date:   Thu, 10 Aug 2023 15:44:56 -0400
From:   "Michael S. Tsirkin" <mst@redhat.com>
To:     Anvesh Jain P <quic_ajainp@quicinc.com>
Cc:     Jason Wang <jasowang@redhat.com>,
        Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
        Venkata Rao Kakani <quic_vkakani@quicinc.com>,
        virtualization@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] virtio_mmio: add suspend and resume calls for
 virtio_mmio devices
Message-ID: <20230810154334-mutt-send-email-mst@kernel.org>
References: <20230728070127.18452-1-quic_ajainp@quicinc.com>
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In-Reply-To: <20230728070127.18452-1-quic_ajainp@quicinc.com>
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On Fri, Jul 28, 2023 at 12:31:27PM +0530, Anvesh Jain P wrote:
> Handle suspend and resume calls for virtio mmio devices from
> PM core. Expose these notifications to virtio drivers that can quiesce and
> resume vq operations. Update virtio pm ops to handle freeze& restore and
> suspend & resume callbacks separately.
> 
> Signed-off-by: Anvesh Jain P <quic_ajainp@quicinc.com>
> Signed-off-by: Venkata Rao Kakani <quic_vkakani@quicinc.com>

okey but what is the motivation? does this addition of 200 LOC
achieve something new? what is the issue fixed here?


> ---
>  drivers/virtio/virtio.c      | 112 +++++++++++++++++++++++++++++++++++
>  drivers/virtio/virtio_mmio.c |  50 +++++++++++++++-
>  include/linux/virtio.h       |  12 ++++
>  3 files changed, 173 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> index 3893dc29eb26..c6f25a267600 100644
> --- a/drivers/virtio/virtio.c
> +++ b/drivers/virtio/virtio.c
> @@ -551,6 +551,118 @@ int virtio_device_restore(struct virtio_device *dev)
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(virtio_device_restore);
> +
> +int virtio_device_suspend(struct virtio_device *dev)
> +{
> +	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
> +
> +	virtio_config_disable(dev);
> +
> +	dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
> +
> +	if (drv && drv->suspend)
> +		return drv->suspend(dev);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(virtio_device_suspend);
> +
> +int virtio_device_resume(struct virtio_device *dev)
> +{
> +	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
> +	int ret;
> +
> +	if (drv && drv->resume) {
> +		ret = drv->resume(dev);
> +		if (ret)
> +			goto err;
> +
> +		if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
> +			virtio_device_ready(dev);
> +
> +		virtio_config_enable(dev);
> +	}
> +
> +	return 0;
> +err:
> +	virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(virtio_device_resume);
> +
> +int virtio_device_suspend_late(struct virtio_device *dev)
> +{
> +	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
> +
> +	virtio_config_disable(dev);
> +
> +	dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
> +
> +	if (drv && drv->suspend_late)
> +		return drv->suspend_late(dev);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(virtio_device_suspend_late);
> +
> +int virtio_device_resume_early(struct virtio_device *dev)
> +{
> +	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
> +	int ret;
> +
> +	if (drv && drv->resume_early) {
> +		ret = drv->resume_early(dev);
> +		if (ret)
> +			goto err;
> +		if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
> +			virtio_device_ready(dev);
> +
> +		virtio_config_enable(dev);
> +	}
> +
> +	return 0;
> +err:
> +	virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(virtio_device_resume_early);
> +
> +int virtio_device_suspend_noirq(struct virtio_device *dev)
> +{
> +	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
> +
> +	virtio_config_disable(dev);
> +
> +	dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
> +
> +	if (drv && drv->suspend_noirq)
> +		return drv->suspend_noirq(dev);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(virtio_device_suspend_noirq);
> +
> +int virtio_device_resume_noirq(struct virtio_device *dev)
> +{
> +	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
> +	int ret;
> +
> +	if (drv && drv->resume_noirq) {
> +		ret = drv->resume_noirq(dev);
> +		if (ret)
> +			goto err;
> +		if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
> +			virtio_device_ready(dev);
> +
> +		virtio_config_enable(dev);
> +	}
> +
> +	return 0;
> +err:
> +	virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(virtio_device_resume_noirq);
>  #endif
>  
>  static int virtio_init(void)
> diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
> index a46a4a29e929..9385c7e65da9 100644
> --- a/drivers/virtio/virtio_mmio.c
> +++ b/drivers/virtio/virtio_mmio.c
> @@ -596,9 +596,57 @@ static int virtio_mmio_restore(struct device *dev)
>  
>  	return virtio_device_restore(&vm_dev->vdev);
>  }
> +static int virtio_mmio_suspend(struct device *dev)
> +{
> +       struct virtio_mmio_device *vm_dev = dev_get_drvdata(dev);
> +
> +       return virtio_device_suspend(&vm_dev->vdev);
> +}
> +
> +static int virtio_mmio_resume(struct device *dev)
> +{
> +       struct virtio_mmio_device *vm_dev = dev_get_drvdata(dev);
> +
> +       return virtio_device_resume(&vm_dev->vdev);
> +}
> +
> +static int virtio_mmio_suspend_late(struct device *dev)
> +{
> +       struct virtio_mmio_device *vm_dev = dev_get_drvdata(dev);
> +
> +       return virtio_device_suspend_late(&vm_dev->vdev);
> +}
> +
> +static int virtio_mmio_resume_early(struct device *dev)
> +{
> +       struct virtio_mmio_device *vm_dev = dev_get_drvdata(dev);
> +
> +       return virtio_device_resume_early(&vm_dev->vdev);
> +}
> +
> +static int virtio_mmio_suspend_noirq(struct device *dev)
> +{
> +       struct virtio_mmio_device *vm_dev = dev_get_drvdata(dev);
> +
> +       return virtio_device_suspend_noirq(&vm_dev->vdev);
> +}
> +
> +static int virtio_mmio_resume_noirq(struct device *dev)
> +{
> +       struct virtio_mmio_device *vm_dev = dev_get_drvdata(dev);
> +
> +       return virtio_device_resume_noirq(&vm_dev->vdev);
> +}
>  
>  static const struct dev_pm_ops virtio_mmio_pm_ops = {
> -	SET_SYSTEM_SLEEP_PM_OPS(virtio_mmio_freeze, virtio_mmio_restore)
> +       .freeze         = virtio_mmio_freeze,
> +       .restore        = virtio_mmio_restore,
> +       .suspend        = virtio_mmio_suspend,
> +       .resume         = virtio_mmio_resume,
> +       .suspend_late   = virtio_mmio_suspend_late,
> +       .resume_early   = virtio_mmio_resume_early,
> +       .suspend_noirq  = virtio_mmio_suspend_noirq,
> +       .resume_noirq   = virtio_mmio_resume_noirq,
>  };
>  #endif
>  
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index de6041deee37..e88b321408e9 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -145,6 +145,12 @@ void virtio_config_changed(struct virtio_device *dev);
>  #ifdef CONFIG_PM_SLEEP
>  int virtio_device_freeze(struct virtio_device *dev);
>  int virtio_device_restore(struct virtio_device *dev);
> +int virtio_device_suspend(struct virtio_device *dev);
> +int virtio_device_resume(struct virtio_device *dev);
> +int virtio_device_suspend_late(struct virtio_device *dev);
> +int virtio_device_resume_early(struct virtio_device *dev);
> +int virtio_device_suspend_noirq(struct virtio_device *dev);
> +int virtio_device_resume_noirq(struct virtio_device *dev);
>  #endif
>  void virtio_reset_device(struct virtio_device *dev);
>  
> @@ -187,6 +193,12 @@ struct virtio_driver {
>  #ifdef CONFIG_PM
>  	int (*freeze)(struct virtio_device *dev);
>  	int (*restore)(struct virtio_device *dev);
> +	int (*suspend)(struct virtio_device *dev);
> +	int (*resume)(struct virtio_device *dev);
> +	int (*suspend_late)(struct virtio_device *dev);
> +	int (*resume_early)(struct virtio_device *dev);
> +	int (*suspend_noirq)(struct virtio_device *dev);
> +	int (*resume_noirq)(struct virtio_device *dev);
>  #endif
>  };
>  
> 
> base-commit: 3f01e9fed8454dcd89727016c3e5b2fbb8f8e50c
> -- 
> 2.17.1