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Message-ID: <7c8945be-2549-ee79-fbdf-4870eca6f908@acm.org>
Date: Mon, 7 Aug 2023 14:02:18 -0700
From: Bart Van Assche <bvanassche@....org>
To: Shyam Saini <shyamsaini@...ux.microsoft.com>,
linux-kernel@...r.kernel.org
Cc: linux-mmc@...r.kernel.org, op-tee@...ts.trustedfirmware.org,
linux-scsi@...r.kernel.org,
Alex Bennée <alex.bennee@...aro.org>,
Tomas Winkler <tomas.winkler@...el.com>,
Ulf Hansson <ulf.hansson@...aro.org>,
Linus Walleij <linus.walleij@...aro.org>,
Arnd Bergmann <arnd.bergmann@...aro.org>,
Ilias Apalodimas <ilias.apalodimas@...aro.org>,
Sumit Garg <sumit.garg@...aro.org>,
Tyler Hicks <code@...icks.com>,
"Srivatsa S . Bhat" <srivatsa@...il.mit.edu>,
Paul Moore <paul@...l-moore.com>,
Allen Pais <apais@...ux.microsoft.com>
Subject: Re: [RFC, PATCH 1/1] rpmb: add Replay Protected Memory Block (RPMB)
driver
On 7/21/23 18:40, Shyam Saini wrote:
> +config RPMB
> + tristate "RPMB partition interface"
> + help
> + Unified RPMB partition interface for RPMB capable devices such as
> + eMMC and UFS. Provides interface for in kernel security controllers to
> + access RPMB partition.
> +
> + If unsure, select N.
Please also mention NVMe.
Please change the word "partition" into "unit" to avoid confusion with
the concept "LBA range partition".
> +static DEFINE_IDA(rpmb_ida);
How are accesses to this IDA serialized?
> +/**
> + * rpmb_get_capacity() - returns the capacity of the rpmb device
> + * @rdev: rpmb device
> + *
> + * Return:
> + * * capacity of the device in units of 128K, on success
> + * * -EINVAL on wrong parameters
> + * * -EOPNOTSUPP if device doesn't support the requested operation
> + * * < 0 if the operation fails
> + */
Why in units of 128 KiB?
> +/**
> + * rpmb_dev_find_by_device() - retrieve rpmb device from the parent device
> + * @parent: parent device of the rpmb device
> + * @target: RPMB target/region within the physical device
> + *
> + * Return: NULL if there is no rpmb device associated with the parent device
> + */
Can an NVMe controller have multiple RPMB units? From the NVMe
specification: "The controller may support multiple RPMB targets."
Can rpmb_dev_find_by_device() be used if multiple RPMB units are
associated with a single controller?
> +/**
> + * rpmb_dev_register - register RPMB partition with the RPMB subsystem
> + * @dev: storage device of the rpmb device
> + * @target: RPMB target/region within the physical device
> + * @ops: device specific operations
> + *
> + * Return: a pointer to rpmb device
> + */
> +struct rpmb_dev *rpmb_dev_register(struct device *dev, u8 target,
> + const struct rpmb_ops *ops)
> +{
> + struct rpmb_dev *rdev;
> + int id;
> + int ret;
> +
> + if (!dev || !ops)
> + return ERR_PTR(-EINVAL);
> +
> + if (!ops->program_key)
> + return ERR_PTR(-EINVAL);
> +
> + if (!ops->get_capacity)
> + return ERR_PTR(-EINVAL);
> +
> + if (!ops->get_write_counter)
> + return ERR_PTR(-EINVAL);
> +
> + if (!ops->write_blocks)
> + return ERR_PTR(-EINVAL);
> +
> + if (!ops->read_blocks)
> + return ERR_PTR(-EINVAL);
> +
> + rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
> + if (!rdev)
> + return ERR_PTR(-ENOMEM);
> +
> + id = ida_simple_get(&rpmb_ida, 0, 0, GFP_KERNEL);
> + if (id < 0) {
> + ret = id;
> + goto exit;
> + }
> +
> + mutex_init(&rdev->lock);
> + rdev->ops = ops;
> + rdev->id = id;
> + rdev->target = target;
> +
> + dev_set_name(&rdev->dev, "rpmb%d", id);
> + rdev->dev.class = &rpmb_class;
> + rdev->dev.parent = dev;
> +
> + rpmb_cdev_prepare(rdev);
> +
> + ret = device_register(&rdev->dev);
> + if (ret)
> + goto exit;
> +
> + rpmb_cdev_add(rdev);
> +
> + dev_dbg(&rdev->dev, "registered device\n");
> +
> + return rdev;
> +
> +exit:
> + if (id >= 0)
> + ida_simple_remove(&rpmb_ida, id);
> + kfree(rdev);
> + return ERR_PTR(ret);
> +}
How is user space software supposed to map an NVMe RPMB target ID to an
RPMB device name?
> +MODULE_AUTHOR("Intel Corporation");
Shouldn't this be the name of a person instead of the name of a company?
Thanks,
Bart.
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