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Date:   Fri, 4 Mar 2022 11:29:44 -0700
From:   Mathieu Poirier <mathieu.poirier@linaro.org>
To:     Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Cc:     Bjorn Andersson <bjorn.andersson@linaro.org>,
        linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-stm32@st-md-mailman.stormreply.com,
        Rob Herring <robh@kernel.org>, Christoph Hellwig <hch@lst.de>,
        Stefano Stabellini <stefanos@xilinx.com>,
        Bruce Ashfield <bruce.ashfield@xilinx.com>
Subject: Re: [RFC PATCH v3 1/4] remoteproc: core: Introduce virtio device
 add/remove functions
Message-ID: <20220304182944.GA1660165@p14s>
References: <20220126162405.1131323-1-arnaud.pouliquen@foss.st.com>
 <20220126162405.1131323-2-arnaud.pouliquen@foss.st.com>
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In-Reply-To: <20220126162405.1131323-2-arnaud.pouliquen@foss.st.com>
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Good morning,

It took longer than expected to review this set as I wanted to make sure the
unwind path was handled properly.

On Wed, Jan 26, 2022 at 05:24:02PM +0100, Arnaud Pouliquen wrote:
> In preparation of the migration of the management of rvdev in
> remoteproc_virtio.c, this patch spins off new functions to manage the
> remoteproc virtio device.
>  - rproc_rvdev_add_device
>  - rproc_rvdev_remove_device
> 
> The rproc_rvdev_add_device and rproc_rvdev_remove_device will be
> moved to remoteproc_virtio.c.
> 
> The rproc_vdev_data structure is introduced to provide information for
> the rvdev creation. This structure allows to manage the rvdev and vrings
> allocation in the rproc_rvdev_add_device function.
> Then the rproc_vdev_data structure will be reused in a next patch as
> platform data structure when the rvdev will rely on a platform device.
>

The last sentence is not needed, please remove.

> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
> ---
> update vs previous revision:
>  - rework rproc_rvdev_add_device function to better manage error cases
> 	- introduce rproc_vdev_data struct
> 	- allocate rvdev in rproc_rvdev_add_device
> ---
>  drivers/remoteproc/remoteproc_core.c | 164 ++++++++++++++++-----------
>  1 file changed, 98 insertions(+), 66 deletions(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 69f51acf235e..83ff44a6a4db 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -66,6 +66,13 @@ static const char * const rproc_crash_names[] = {
>  	[RPROC_FATAL_ERROR]	= "fatal error",
>  };
>  
> +struct rproc_vdev_data {
> +	struct fw_rsc_vdev *rsc;
> +	u32 rsc_offset;
> +	unsigned int id;
> +	unsigned int index;
> +};

Here this structure is introduced without documentation and in patch 3/4 it is
moved to remoteproc_internal.h where documentation is added.  Please added there
(with documentation) in the first place.  That way it doesn't have to be moved
again.

> +
>  /* translate rproc_crash_type to string */
>  static const char *rproc_crash_to_string(enum rproc_crash_type type)
>  {
> @@ -484,74 +491,23 @@ static int copy_dma_range_map(struct device *to, struct device *from)
>  	return 0;
>  }
>  
> -/**
> - * rproc_handle_vdev() - handle a vdev fw resource
> - * @rproc: the remote processor
> - * @ptr: the vring resource descriptor
> - * @offset: offset of the resource entry
> - * @avail: size of available data (for sanity checking the image)
> - *
> - * This resource entry requests the host to statically register a virtio
> - * device (vdev), and setup everything needed to support it. It contains
> - * everything needed to make it possible: the virtio device id, virtio
> - * device features, vrings information, virtio config space, etc...
> - *
> - * Before registering the vdev, the vrings are allocated from non-cacheable
> - * physically contiguous memory. Currently we only support two vrings per
> - * remote processor (temporary limitation). We might also want to consider
> - * doing the vring allocation only later when ->find_vqs() is invoked, and
> - * then release them upon ->del_vqs().
> - *
> - * Note: @da is currently not really handled correctly: we dynamically
> - * allocate it using the DMA API, ignoring requested hard coded addresses,
> - * and we don't take care of any required IOMMU programming. This is all
> - * going to be taken care of when the generic iommu-based DMA API will be
> - * merged. Meanwhile, statically-addressed iommu-based firmware images should
> - * use RSC_DEVMEM resource entries to map their required @da to the physical
> - * address of their base CMA region (ouch, hacky!).
> - *
> - * Return: 0 on success, or an appropriate error code otherwise
> - */
> -static int rproc_handle_vdev(struct rproc *rproc, void *ptr,
> -			     int offset, int avail)
> +static struct rproc_vdev *
> +rproc_rvdev_add_device(struct rproc *rproc, struct rproc_vdev_data *rvdev_data)
>  {
> -	struct fw_rsc_vdev *rsc = ptr;
> -	struct device *dev = &rproc->dev;
>  	struct rproc_vdev *rvdev;
> -	int i, ret;
> +	struct fw_rsc_vdev *rsc = rvdev_data->rsc;
>  	char name[16];
> -
> -	/* make sure resource isn't truncated */
> -	if (struct_size(rsc, vring, rsc->num_of_vrings) + rsc->config_len >
> -			avail) {
> -		dev_err(dev, "vdev rsc is truncated\n");
> -		return -EINVAL;
> -	}
> -
> -	/* make sure reserved bytes are zeroes */
> -	if (rsc->reserved[0] || rsc->reserved[1]) {
> -		dev_err(dev, "vdev rsc has non zero reserved bytes\n");
> -		return -EINVAL;
> -	}
> -
> -	dev_dbg(dev, "vdev rsc: id %d, dfeatures 0x%x, cfg len %d, %d vrings\n",
> -		rsc->id, rsc->dfeatures, rsc->config_len, rsc->num_of_vrings);
> -
> -	/* we currently support only two vrings per rvdev */
> -	if (rsc->num_of_vrings > ARRAY_SIZE(rvdev->vring)) {
> -		dev_err(dev, "too many vrings: %d\n", rsc->num_of_vrings);
> -		return -EINVAL;
> -	}
> +	int i, ret;
>  
>  	rvdev = kzalloc(sizeof(*rvdev), GFP_KERNEL);
>  	if (!rvdev)
> -		return -ENOMEM;
> +		return ERR_PTR(-ENOMEM);
>  
>  	kref_init(&rvdev->refcount);
>  
> -	rvdev->id = rsc->id;
> +	rvdev->id = rvdev_data->id;
>  	rvdev->rproc = rproc;
> -	rvdev->index = rproc->nb_vdev++;
> +	rvdev->index = rvdev_data->index;
>  
>  	/* Initialise vdev subdevice */
>  	snprintf(name, sizeof(name), "vdev%dbuffer", rvdev->index);
> @@ -563,7 +519,7 @@ static int rproc_handle_vdev(struct rproc *rproc, void *ptr,
>  	ret = device_register(&rvdev->dev);
>  	if (ret) {
>  		put_device(&rvdev->dev);
> -		return ret;
> +		return ERR_PTR(ret);
>  	}
>  
>  	ret = copy_dma_range_map(&rvdev->dev, rproc->dev.parent);
> @@ -576,7 +532,7 @@ static int rproc_handle_vdev(struct rproc *rproc, void *ptr,
>  	ret = dma_coerce_mask_and_coherent(&rvdev->dev,
>  					   dma_get_mask(rproc->dev.parent));
>  	if (ret) {
> -		dev_warn(dev,
> +		dev_warn(&rvdev->dev,
>  			 "Failed to set DMA mask %llx. Trying to continue... (%pe)\n",
>  			 dma_get_mask(rproc->dev.parent), ERR_PTR(ret));
>  	}
> @@ -589,7 +545,7 @@ static int rproc_handle_vdev(struct rproc *rproc, void *ptr,
>  	}
>  
>  	/* remember the resource offset*/
> -	rvdev->rsc_offset = offset;
> +	rvdev->rsc_offset = rvdev_data->rsc_offset;
>  
>  	/* allocate the vring resources */
>  	for (i = 0; i < rsc->num_of_vrings; i++) {
> @@ -605,21 +561,20 @@ static int rproc_handle_vdev(struct rproc *rproc, void *ptr,
>  
>  	rproc_add_subdev(rproc, &rvdev->subdev);
>  
> -	return 0;
> +	return rvdev;
>  
>  unwind_vring_allocations:
>  	for (i--; i >= 0; i--)
>  		rproc_free_vring(&rvdev->vring[i]);
>  free_rvdev:
>  	device_unregister(&rvdev->dev);
> -	return ret;
> +	return ERR_PTR(ret);
>  }
>  
> -void rproc_vdev_release(struct kref *ref)
> +static void rproc_rvdev_remove_device(struct rproc_vdev *rvdev)
>  {
> -	struct rproc_vdev *rvdev = container_of(ref, struct rproc_vdev, refcount);
> -	struct rproc_vring *rvring;
>  	struct rproc *rproc = rvdev->rproc;
> +	struct rproc_vring *rvring;
>  	int id;
>  
>  	for (id = 0; id < ARRAY_SIZE(rvdev->vring); id++) {
> @@ -632,6 +587,83 @@ void rproc_vdev_release(struct kref *ref)
>  	device_unregister(&rvdev->dev);
>  }
>  
> +/**
> + * rproc_handle_vdev() - handle a vdev fw resource
> + * @rproc: the remote processor
> + * @ptr: the vring resource descriptor
> + * @offset: offset of the resource entry
> + * @avail: size of available data (for sanity checking the image)
> + *
> + * This resource entry requests the host to statically register a virtio
> + * device (vdev), and setup everything needed to support it. It contains
> + * everything needed to make it possible: the virtio device id, virtio
> + * device features, vrings information, virtio config space, etc...
> + *
> + * Before registering the vdev, the vrings are allocated from non-cacheable
> + * physically contiguous memory. Currently we only support two vrings per
> + * remote processor (temporary limitation). We might also want to consider
> + * doing the vring allocation only later when ->find_vqs() is invoked, and
> + * then release them upon ->del_vqs().
> + *
> + * Note: @da is currently not really handled correctly: we dynamically
> + * allocate it using the DMA API, ignoring requested hard coded addresses,
> + * and we don't take care of any required IOMMU programming. This is all
> + * going to be taken care of when the generic iommu-based DMA API will be
> + * merged. Meanwhile, statically-addressed iommu-based firmware images should
> + * use RSC_DEVMEM resource entries to map their required @da to the physical
> + * address of their base CMA region (ouch, hacky!).
> + *
> + * Return: 0 on success, or an appropriate error code otherwise
> + */
> +static int rproc_handle_vdev(struct rproc *rproc, void *ptr,
> +			     int offset, int avail)
> +{
> +	struct fw_rsc_vdev *rsc = ptr;
> +	struct device *dev = &rproc->dev;
> +	struct rproc_vdev *rvdev;
> +	struct rproc_vdev_data rvdev_data;
> +
> +	/* make sure resource isn't truncated */
> +	if (struct_size(rsc, vring, rsc->num_of_vrings) + rsc->config_len >
> +			avail) {
> +		dev_err(dev, "vdev rsc is truncated\n");
> +		return -EINVAL;
> +	}
> +
> +	/* make sure reserved bytes are zeroes */
> +	if (rsc->reserved[0] || rsc->reserved[1]) {
> +		dev_err(dev, "vdev rsc has non zero reserved bytes\n");
> +		return -EINVAL;
> +	}
> +
> +	dev_dbg(dev, "vdev rsc: id %d, dfeatures 0x%x, cfg len %d, %d vrings\n",
> +		rsc->id, rsc->dfeatures, rsc->config_len, rsc->num_of_vrings);
> +
> +	/* we currently support only two vrings per rvdev */
> +	if (rsc->num_of_vrings > ARRAY_SIZE(rvdev->vring)) {
> +		dev_err(dev, "too many vrings: %d\n", rsc->num_of_vrings);
> +		return -EINVAL;
> +	}
> +
> +	rvdev_data.id = rsc->id;
> +	rvdev_data.index = rproc->nb_vdev++;
> +	rvdev_data.rsc_offset = offset;
> +	rvdev_data.rsc = rsc;
> +
> +	rvdev = rproc_rvdev_add_device(rproc, &rvdev_data);
> +	if (IS_ERR(rvdev))
> +		return PTR_ERR(rvdev);
> +
> +	return 0;
> +}
> +
> +void rproc_vdev_release(struct kref *ref)
> +{
> +	struct rproc_vdev *rvdev = container_of(ref, struct rproc_vdev, refcount);
> +
> +	rproc_rvdev_remove_device(rvdev);
> +}
> +
>  /**
>   * rproc_handle_trace() - handle a shared trace buffer resource
>   * @rproc: the remote processor
> -- 
> 2.25.1
>