Re: [PATCH v5 2/3] mmc: block: register RPMB partition with the RPMB subsystem

[Manuel Traut <manut@mecka.net>]

On Fri, Apr 26, 2024 at 03:24:21PM +0200, Jens Wiklander wrote:
> On Thu, Apr 25, 2024 at 10:43 AM Manuel Traut <manut@mecka.net> wrote:
> >
> > On Mon, Apr 22, 2024 at 11:19:35AM +0200, 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 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.
> > >
> > > Taking the needed reference to md->disk in mmc_blk_alloc_rpmb_part()
> > > instead of in mmc_rpmb_chrdev_open(). This is needed by the
> > > route_frames() function pointer in struct rpmb_ops.
> > >
> > > 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 | 241 ++++++++++++++++++++++++++++++++++++++-
> > >  1 file changed, 239 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> > > index 32d49100dff5..a7f126fbc605 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>
> > > @@ -76,6 +78,48 @@ MODULE_ALIAS("mmc:block");
> > >  #define MMC_EXTRACT_INDEX_FROM_ARG(x) ((x & 0x00FF0000) >> 16)
> > >  #define MMC_EXTRACT_VALUE_FROM_ARG(x) ((x & 0x0000FF00) >> 8)
> > >
> > > +/**
> > > + * struct rpmb_frame - rpmb frame as defined by eMMC 5.1 (JESD84-B51)
> > > + *
> > > + * @stuff        : stuff bytes
> > > + * @key_mac      : The authentication key or the message authentication
> > > + *                 code (MAC) depending on the request/response type.
> > > + *                 The MAC will be delivered in the last (or the only)
> > > + *                 block of data.
> > > + * @data         : Data to be written or read by signed access.
> > > + * @nonce        : Random number generated by the host for the requests
> > > + *                 and copied to the response by the RPMB engine.
> > > + * @write_counter: Counter value for the total amount of the successful
> > > + *                 authenticated data write requests made by the host.
> > > + * @addr         : Address of the data to be programmed to or read
> > > + *                 from the RPMB. Address is the serial number of
> > > + *                 the accessed block (half sector 256B).
> > > + * @block_count  : Number of blocks (half sectors, 256B) requested to be
> > > + *                 read/programmed.
> > > + * @result       : Includes information about the status of the write counter
> > > + *                 (valid, expired) and result of the access made to the RPMB.
> > > + * @req_resp     : Defines the type of request and response to/from the memory.
> > > + *
> > > + * The stuff bytes and big-endian properties are modeled to fit to the spec.
> > > + */
> > > +struct rpmb_frame {
> > > +     u8     stuff[196];
> > > +     u8     key_mac[32];
> > > +     u8     data[256];
> > > +     u8     nonce[16];
> > > +     __be32 write_counter;
> > > +     __be16 addr;
> > > +     __be16 block_count;
> > > +     __be16 result;
> > > +     __be16 req_resp;
> > > +} __packed;
> > > +
> > > +#define RPMB_PROGRAM_KEY       0x1    /* Program RPMB Authentication Key */
> > > +#define RPMB_GET_WRITE_COUNTER 0x2    /* Read RPMB write counter */
> > > +#define RPMB_WRITE_DATA        0x3    /* Write data to RPMB partition */
> > > +#define RPMB_READ_DATA         0x4    /* Read data from RPMB partition */
> > > +#define RPMB_RESULT_READ       0x5    /* Read result request  (Internal) */
> > > +
> > >  static DEFINE_MUTEX(block_mutex);
> > >
> > >  /*
> > > @@ -163,6 +207,7 @@ struct mmc_rpmb_data {
> > >       int id;
> > >       unsigned int part_index;
> > >       struct mmc_blk_data *md;
> > > +     struct rpmb_dev *rdev;
> > >       struct list_head node;
> > >  };
> > >
> > > @@ -2672,7 +2717,6 @@ static int mmc_rpmb_chrdev_open(struct inode *inode, struct file *filp)
> > >
> > >       get_device(&rpmb->dev);
> > >       filp->private_data = rpmb;
> > > -     mmc_blk_get(rpmb->md->disk);
> > >
> > >       return nonseekable_open(inode, filp);
> > >  }
> > > @@ -2682,7 +2726,6 @@ static int mmc_rpmb_chrdev_release(struct inode *inode, struct file *filp)
> > >       struct mmc_rpmb_data *rpmb = container_of(inode->i_cdev,
> > >                                                 struct mmc_rpmb_data, chrdev);
> > >
> > > -     mmc_blk_put(rpmb->md);
> > >       put_device(&rpmb->dev);
> > >
> > >       return 0;
> > > @@ -2703,10 +2746,165 @@ static void mmc_blk_rpmb_device_release(struct device *dev)
> > >  {
> > >       struct mmc_rpmb_data *rpmb = dev_get_drvdata(dev);
> > >
> > > +     rpmb_dev_unregister(rpmb->rdev);
> > > +     mmc_blk_put(rpmb->md);
> > >       ida_simple_remove(&mmc_rpmb_ida, rpmb->id);
> > >       kfree(rpmb);
> > >  }
> > >
> > > +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 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]) {
> > > +                     free_idata(idata, n);
> > > +                     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)
> > > +{
> > > +     /*
> > > +      * The size of an RPMB frame must match what's expected by the
> > > +      * hardware.
> > > +      */
> > > +     BUILD_BUG_ON(sizeof(struct rpmb_frame) != 512);
> > > +
> > > +     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;
> >
> > I tested the series on a i.MX8MM with a eMMC connected via the imx-sdhci
> > controller. Reading from RPMB does not work. It ends in timeouts due to
> > no response from the SDHCI controller.
> >
> > If idata->buf is allocated here with kmalloc(buf_bytes, GFP_KERNEL) and
> > the content of buf is copied to the new allocated area, transfers succeed.
> >
> > Is it possible that idata->buf is not DMA capable? Any other ideas?
> 
> Thanks for testing. I don't know, the idata->buf is allocated using
> alloc_pages_exact(nr_pages * PAGE_SIZE, GFP_KERNEL | __GFP_ZERO); in
> optee_pool_op_alloc_helper().

Is this really true for idata->buf or isnt the complete RPMB frame memory
allocated like this and therefore idata->buf not page aligned?

For RPMB via tee-supplicant the idata->buf is allocated within memdup_user
and therefore page aligned.

> Alternatively, it's from the memory
> range mapped using memremap() in optee_config_shm_memremap(), but
> that's only if you don't have "dynamic shared memory is enabled" in
> the boot log.

"dynamic shared memory is enabled" is in the bootlog, ..

Thanks for your comments,
Manuel