Re: [PATCH v2 2/3] mmc: block: register RPMB partition with the RPMB subsystem

["Jorge Ramirez-Ortiz, Foundries" <jorge@foundries.io>]

On 31/01/24 18:43:46, Jens Wiklander wrote:
> Register eMMC RPMB partition with the RPMB subsystem and provide
> an implementation for the RPMB access operations abstracting
> the actual multi step process.
>
> Add callbacks for getting and putting the needed resources, that is, the
> RPMB data and the RPMB disk.
>
> Add a callback to extract the needed device information at registration
> to avoid accessing the struct mmc_card at a later stage as we're not
> holding a reference counter for this struct.
>
> Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
> Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
> Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
> ---
>  drivers/mmc/core/block.c | 177 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 177 insertions(+)
>
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index 32d49100dff5..5286e0b3a5a2 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -33,6 +33,7 @@
>  #include <linux/cdev.h>
>  #include <linux/mutex.h>
>  #include <linux/scatterlist.h>
> +#include <linux/string.h>
>  #include <linux/string_helpers.h>
>  #include <linux/delay.h>
>  #include <linux/capability.h>
> @@ -40,6 +41,7 @@
>  #include <linux/pm_runtime.h>
>  #include <linux/idr.h>
>  #include <linux/debugfs.h>
> +#include <linux/rpmb.h>
>
>  #include <linux/mmc/ioctl.h>
>  #include <linux/mmc/card.h>
> @@ -163,6 +165,7 @@ struct mmc_rpmb_data {
>  	int id;
>  	unsigned int part_index;
>  	struct mmc_blk_data *md;
> +	struct rpmb_dev *rdev;
>  	struct list_head node;
>  };
>
> @@ -2707,6 +2710,169 @@ static void mmc_blk_rpmb_device_release(struct device *dev)
>  	kfree(rpmb);
>  }
>
> +static void rpmb_op_mmc_get_resources(struct device *dev)
> +{
> +	struct mmc_rpmb_data *rpmb = dev_get_drvdata(dev);
> +
> +	/*
> +	 * When the MMC card is removed rpmb_dev_unregister() is called
> +	 * from mmc_blk_remove_rpmb_part(). That removes references to the
> +	 * devices in struct mmc_rpmb_data and rpmb->md. Since struct
> +	 * rpmb_dev can still reach those structs we must hold a reference
> +	 * until struct rpmb_dev also is released.
> +	 *
> +	 * This is analogous to what's done in mmc_rpmb_chrdev_open() and
> +	 * mmc_rpmb_chrdev_release() below.
> +	 */
> +	get_device(dev);
> +	mmc_blk_get(rpmb->md->disk);
> +}
> +
> +static void rpmb_op_mmc_put_resources(struct device *dev)
> +{
> +	struct mmc_rpmb_data *rpmb = dev_get_drvdata(dev);
> +
> +	mmc_blk_put(rpmb->md);
> +	put_device(dev);
> +}
> +
> +static struct mmc_blk_ioc_data **alloc_idata(struct mmc_rpmb_data *rpmb,
> +					     unsigned int cmd_count)
> +{
> +	struct mmc_blk_ioc_data **idata;
> +	unsigned int n;
> +
> +	idata = kcalloc(cmd_count, sizeof(*idata), GFP_KERNEL);
> +	if (!idata)
> +		return NULL;
> +
> +	for (n = 0; n < cmd_count; n++) {
> +		idata[n] = kcalloc(1, sizeof(**idata), GFP_KERNEL);
> +		if (!idata[n]) {
> +			kfree(idata);

don't you need to unwind these allocations on error?

> +			return NULL;
> +		}
> +		idata[n]->rpmb = rpmb;
> +	}
> +
> +	return idata;
> +}
> +
> +static void set_idata(struct mmc_blk_ioc_data *idata, u32 opcode,
> +		      int write_flag, u8 *buf, unsigned int buf_bytes)
> +{
> +	idata->ic.opcode = opcode;
> +	idata->ic.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
> +	idata->ic.write_flag = write_flag;
> +	idata->ic.blksz = sizeof(struct rpmb_frame);
> +	idata->ic.blocks = buf_bytes /  idata->ic.blksz;
> +	idata->buf = buf;
> +	idata->buf_bytes = buf_bytes;
> +}
> +
> +static void free_idata(struct mmc_blk_ioc_data **idata, unsigned int cmd_count)
> +{
> +	unsigned int n;
> +
> +	for (n = 0; n < cmd_count; n++)
> +		kfree(idata[n]);
> +	kfree(idata);
> +}
> +
> +static int rpmb_op_mmc_route_frames(struct device *dev, bool write, u8 *req,
> +				    unsigned int req_len, u8 *resp,
> +				    unsigned int resp_len)
> +{
> +	struct mmc_rpmb_data *rpmb = dev_get_drvdata(dev);
> +	struct mmc_blk_data *md = rpmb->md;
> +	struct mmc_blk_ioc_data **idata;
> +	unsigned int cmd_count;
> +	struct request *rq;
> +	int ret;
> +
> +	if (write)
> +		cmd_count = 3;
> +	else
> +		cmd_count = 2;
> +
> +	if (IS_ERR(md->queue.card))
> +		return PTR_ERR(md->queue.card);
> +
> +	idata = alloc_idata(rpmb, cmd_count);
> +	if (!idata)
> +		return -ENOMEM;
> +
> +	if (write) {
> +		struct rpmb_frame *frm = (struct rpmb_frame *)resp;
> +
> +		/* Send write request frame(s) */
> +		set_idata(idata[0], MMC_WRITE_MULTIPLE_BLOCK,
> +			  1 | MMC_CMD23_ARG_REL_WR, req, req_len);
> +
> +		/* Send result request frame */
> +		memset(frm, 0, sizeof(*frm));
> +		frm->req_resp = cpu_to_be16(RPMB_RESULT_READ);
> +		set_idata(idata[1], MMC_WRITE_MULTIPLE_BLOCK, 1, resp,
> +			  resp_len);
> +
> +		/* Read response frame */
> +		set_idata(idata[2], MMC_READ_MULTIPLE_BLOCK, 0, resp, resp_len);
> +	} else {
> +		/* Send write request frame(s) */
> +		set_idata(idata[0], MMC_WRITE_MULTIPLE_BLOCK, 1, req, req_len);
> +
> +		/* Read response frame */
> +		set_idata(idata[1], MMC_READ_MULTIPLE_BLOCK, 0, resp, resp_len);
> +	}
> +
> +	rq = blk_mq_alloc_request(md->queue.queue, REQ_OP_DRV_OUT, 0);
> +	if (IS_ERR(rq)) {
> +		ret = PTR_ERR(rq);
> +		goto out;
> +	}
> +
> +	req_to_mmc_queue_req(rq)->drv_op = MMC_DRV_OP_IOCTL_RPMB;
> +	req_to_mmc_queue_req(rq)->drv_op_result = -EIO;
> +	req_to_mmc_queue_req(rq)->drv_op_data = idata;
> +	req_to_mmc_queue_req(rq)->ioc_count = cmd_count;
> +	blk_execute_rq(rq, false);
> +	ret = req_to_mmc_queue_req(rq)->drv_op_result;
> +
> +	blk_mq_free_request(rq);
> +
> +out:
> +	free_idata(idata, cmd_count);
> +	return ret;
> +}
> +
> +static int rpmb_op_mmc_set_dev_info(struct device *dev, struct rpmb_dev *rdev)
> +{
> +	struct mmc_rpmb_data *rpmb = dev_get_drvdata(dev);
> +	struct mmc_card *card = rpmb->md->queue.card;
> +	unsigned int n;
> +	u32 cid[4];
> +
> +	for (n = 0; n < 4; n++)
> +		cid[n] = be32_to_cpu(card->raw_cid[n]);
> +
> +	rdev->dev_id = kmemdup(cid, sizeof(cid), GFP_KERNEL);
> +	if (!rdev->dev_id)
> +		return -ENOMEM;
> +	rdev->dev_id_len = sizeof(cid);
> +	rdev->reliable_wr_count = card->ext_csd.raw_rpmb_size_mult;
> +	rdev->capacity = card->ext_csd.rel_sectors;
> +
> +	return 0;
> +}
> +
> +static struct rpmb_ops rpmb_mmc_ops = {
> +	.type = RPMB_TYPE_EMMC,
> +	.get_resources = rpmb_op_mmc_get_resources,
> +	.put_resources = rpmb_op_mmc_put_resources,
> +	.route_frames = rpmb_op_mmc_route_frames,
> +	.set_dev_info = rpmb_op_mmc_set_dev_info,
> +};
> +
>  static int mmc_blk_alloc_rpmb_part(struct mmc_card *card,
>  				   struct mmc_blk_data *md,
>  				   unsigned int part_index,
> @@ -2751,6 +2917,14 @@ static int mmc_blk_alloc_rpmb_part(struct mmc_card *card,
>  		goto out_put_device;
>  	}
>
> +	rpmb->rdev = rpmb_dev_register(&rpmb->dev, &rpmb_mmc_ops);
> +	if (IS_ERR(rpmb->rdev)) {
> +		pr_err("%s: could not register RPMB device\n", rpmb_name);
> +		ret = PTR_ERR(rpmb->rdev);
> +		rpmb->rdev = NULL;
> +		goto out_cdev_device_del;
> +	}
> +
>  	list_add(&rpmb->node, &md->rpmbs);
>
>  	string_get_size((u64)size, 512, STRING_UNITS_2,
> @@ -2762,6 +2936,8 @@ static int mmc_blk_alloc_rpmb_part(struct mmc_card *card,
>
>  	return 0;
>
> +out_cdev_device_del:
> +	cdev_device_del(&rpmb->chrdev, &rpmb->dev);
>  out_put_device:
>  	put_device(&rpmb->dev);
>  	return ret;
> @@ -2770,6 +2946,7 @@ static int mmc_blk_alloc_rpmb_part(struct mmc_card *card,
>  static void mmc_blk_remove_rpmb_part(struct mmc_rpmb_data *rpmb)
>
>  {
> +	rpmb_dev_unregister(rpmb->rdev);
>  	cdev_device_del(&rpmb->chrdev, &rpmb->dev);
>  	put_device(&rpmb->dev);
>  }
> --
> 2.34.1
>