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Message-ID: <Z66CUnDenq0yQgBu@kernel.org>
Date: Fri, 14 Feb 2025 01:37:54 +0200
From: Jarkko Sakkinen <jarkko@...nel.org>
To: Stuart Yoder <stuart.yoder@....com>
Cc: linux-integrity@...r.kernel.org, peterhuewe@....de, jgg@...pe.ca,
sudeep.holla@....com, rafael@...nel.org, lenb@...nel.org,
linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/5] tpm_crb: implement driver compliant to CRB over
FF-A
On Thu, Feb 13, 2025 at 04:22:44PM -0600, Stuart Yoder wrote:
>
>
> On 2/13/25 4:14 PM, Jarkko Sakkinen wrote:
> > On Wed, Feb 12, 2025 at 04:05:44PM -0600, Stuart Yoder wrote:
> > > The Arm specification TPM Service CRB over FF-A specification
> > > defines the FF-A messages to interact with a CRB-based TPM
> > > implemented as an FF-A secure partition.
> > >
> > > Spec URL:
> > > https://developer.arm.com/documentation/den0138/latest/
> > >
> > > This driver is probed when a TPM Secure Partition is
> > > discovered by the FF-A subsystem. It exposes APIs
> > > used by the TPM CRB driver to send notifications to
> > > the TPM.
> > >
> > > Signed-off-by: Stuart Yoder <stuart.yoder@....com>
> > > ---
> > > drivers/char/tpm/Kconfig | 9 +
> > > drivers/char/tpm/Makefile | 1 +
> > > drivers/char/tpm/tpm_ffa_crb.c | 310 +++++++++++++++++++++++++++++++++
> > > drivers/char/tpm/tpm_ffa_crb.h | 30 ++++
> > > 4 files changed, 350 insertions(+)
> > > create mode 100644 drivers/char/tpm/tpm_ffa_crb.c
> > > create mode 100644 drivers/char/tpm/tpm_ffa_crb.h
> > >
> > > diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
> > > index 0fc9a510e059..af5ba7c63927 100644
> > > --- a/drivers/char/tpm/Kconfig
> > > +++ b/drivers/char/tpm/Kconfig
> > > @@ -210,6 +210,15 @@ config TCG_CRB
> > > from within Linux. To compile this driver as a module, choose
> > > M here; the module will be called tpm_crb.
> > > +config TCG_ARM_FFA_CRB
> > > + tristate "TPM CRB over Arm FF-A Transport"
> > > + depends on ARM_FFA_TRANSPORT
> > > + default y if (TCG_CRB && ARM_FFA_TRANSPORT)
> > > + help
> > > + If the Arm FF-A transport is used to access the TPM say Yes.
> > > + To compile this driver as a module, choose M here; the module
> > > + will be called tpm_ffa_crb.
> > > +
> > > config TCG_VTPM_PROXY
> > > tristate "VTPM Proxy Interface"
> > > depends on TCG_TPM
> > > diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
> > > index 9bb142c75243..21f2eb5a485e 100644
> > > --- a/drivers/char/tpm/Makefile
> > > +++ b/drivers/char/tpm/Makefile
> > > @@ -42,5 +42,6 @@ obj-$(CONFIG_TCG_IBMVTPM) += tpm_ibmvtpm.o
> > > obj-$(CONFIG_TCG_TIS_ST33ZP24) += st33zp24/
> > > obj-$(CONFIG_TCG_XEN) += xen-tpmfront.o
> > > obj-$(CONFIG_TCG_CRB) += tpm_crb.o
> > > +obj-$(CONFIG_TCG_ARM_FFA_CRB) += tpm_ffa_crb.o
> > > obj-$(CONFIG_TCG_VTPM_PROXY) += tpm_vtpm_proxy.o
> > > obj-$(CONFIG_TCG_FTPM_TEE) += tpm_ftpm_tee.o
> > > diff --git a/drivers/char/tpm/tpm_ffa_crb.c b/drivers/char/tpm/tpm_ffa_crb.c
> > > new file mode 100644
> > > index 000000000000..56bd77864a47
> > > --- /dev/null
> > > +++ b/drivers/char/tpm/tpm_ffa_crb.c
> > > @@ -0,0 +1,310 @@
> > > +// SPDX-License-Identifier: GPL-2.0-only
> > > +/*
> > > + * Copyright (C) 2024 Arm Ltd.
> > > + *
> > > + * Maintained by: <tpmdd-devel@...ts.sourceforge.net>
> > > + *
> > > + * This device driver implements the TPM CRB start method
> > > + * as defined in the TPM Service Command Response Buffer
> > > + * Interface Over FF-A (DEN0138).
> > > + */
> > > +
> > > +#define pr_fmt(fmt) "FFA_CRB: " fmt
> > > +
> > > +#include <linux/arm_ffa.h>
> > > +#include "tpm_ffa_crb.h"
> > > +
> > > +/* TPM service function status codes */
> > > +#define FFA_CRB_OK 0x05000001
> > > +#define FFA_CRB_OK_RESULTS_RETURNED 0x05000002
> > > +#define FFA_CRB_NOFUNC 0x8e000001
> > > +#define FFA_CRB_NOTSUP 0x8e000002
> > > +#define FFA_CRB_INVARG 0x8e000005
> > > +#define FFA_CRB_INV_CRB_CTRL_DATA 0x8e000006
> > > +#define FFA_CRB_ALREADY 0x8e000009
> > > +#define FFA_CRB_DENIED 0x8e00000a
> > > +#define FFA_CRB_NOMEM 0x8e00000b
> > > +
> > > +#define FFA_CRB_VERSION_MAJOR 1
> > > +#define FFA_CRB_VERSION_MINOR 0
> > > +
> > > +/* version encoding */
> > > +#define FFA_CRB_MAJOR_VERSION_MASK GENMASK(30, 16)
> > > +#define FFA_CRB_MINOR_VERSION_MASK GENMASK(15, 0)
> > > +#define FFA_CRB_MAJOR_VERSION(x) ((u16)(FIELD_GET(FFA_CRB_MAJOR_VERSION_MASK, (x))))
> > > +#define FFA_CRB_MINOR_VERSION(x) ((u16)(FIELD_GET(FFA_CRB_MINOR_VERSION_MASK, (x))))
> > > +
> > > +/*
> > > + * Normal world sends requests with FFA_MSG_SEND_DIRECT_REQ and
> > > + * responses are returned with FFA_MSG_SEND_DIRECT_RESP for normal
> > > + * messages.
> > > + *
> > > + * All requests with FFA_MSG_SEND_DIRECT_REQ and FFA_MSG_SEND_DIRECT_RESP
> > > + * are using the AArch32 SMC calling convention with register usage as
> > > + * defined in FF-A specification:
> > > + * w0: Function ID (0x8400006F or 0x84000070)
> > > + * w1: Source/Destination IDs
> > > + * w2: Reserved (MBZ)
> > > + * w3-w7: Implementation defined, free to be used below
> > > + */
> > > +
> > > +/*
> > > + * Returns the version of the interface that is available
> > > + * Call register usage:
> > > + * w3: Not used (MBZ)
> > > + * w4: TPM service function ID, FFA_CRB_GET_INTERFACE_VERSION
> > > + * w5-w7: Reserved (MBZ)
> > > + *
> > > + * Return register usage:
> > > + * w3: Not used (MBZ)
> > > + * w4: TPM service function status
> > > + * w5: TPM service interface version
> > > + * Bits[31:16]: major version
> > > + * Bits[15:0]: minor version
> > > + * w6-w7: Reserved (MBZ)
> > > + *
> > > + * Possible function status codes in register w4:
> > > + * CRB_FFA_OK_RESULTS_RETURNED: The version of the interface has been
> > > + * returned.
> > > + */
> > > +#define FFA_CRB_GET_INTERFACE_VERSION 0x0f000001
> > > +
> > > +/*
> > > + * Return information on a given feature of the TPM service
> > > + * Call register usage:
> > > + * w3: Not used (MBZ)
> > > + * w4: TPM service function ID, FFA_CRB_START
> > > + * w5: Start function qualifier
> > > + * Bits[31:8] (MBZ)
> > > + * Bits[7:0]
> > > + * 0: Notifies TPM that a command is ready to be processed
> > > + * 1: Notifies TPM that a locality request is ready to be processed
> > > + * w6: TPM locality, one of 0..4
> > > + * -If the start function qualifier is 0, identifies the locality
> > > + * from where the command originated.
> > > + * -If the start function qualifier is 1, identifies the locality
> > > + * of the locality request
> > > + * w6-w7: Reserved (MBZ)
> > > + *
> > > + * Return register usage:
> > > + * w3: Not used (MBZ)
> > > + * w4: TPM service function status
> > > + * w5-w7: Reserved (MBZ)
> > > + *
> > > + * Possible function status codes in register w4:
> > > + * FFA_CRB_OK: the TPM service has been notified successfully
> > > + * FFA_CRB_INVARG: one or more arguments are not valid
> > > + * FFA_CRB_INV_CRB_CTRL_DATA: CRB control data or locality control
> > > + * data at the given TPM locality is not valid
> > > + * FFA_CRB_DENIED: the TPM has previously disabled locality requests and
> > > + * command processing at the given locality
> > > + */
> > > +#define FFA_CRB_START 0x0f000201
> > > +
> > > +struct ffa_crb {
> > > + struct ffa_device *ffa_dev;
> > > + u16 major_version;
> > > + u16 minor_version;
> > > + struct mutex msg_data_lock;
> > > + struct ffa_send_direct_data direct_msg_data;
> > > +};
> > > +
> > > +static struct ffa_crb *ffa_crb;
> > > +
> > > +static int ffa_crb_to_linux_errno(int errno)
> > > +{
> > > + int rc;
> > > +
> > > + switch (errno) {
> > > + case FFA_CRB_OK:
> > > + rc = 0;
> > > + break;
> > > + case FFA_CRB_OK_RESULTS_RETURNED:
> > > + rc = 0;
> > > + break;
> > > + case FFA_CRB_NOFUNC:
> > > + rc = -ENOENT;
> > > + break;
> > > + case FFA_CRB_NOTSUP:
> > > + rc = -EPERM;
> > > + break;
> > > + case FFA_CRB_INVARG:
> > > + rc = -EINVAL;
> > > + break;
> > > + case FFA_CRB_INV_CRB_CTRL_DATA:
> > > + rc = -ENOEXEC;
> > > + break;
> > > + case FFA_CRB_ALREADY:
> > > + rc = -EEXIST;
> > > + break;
> > > + case FFA_CRB_DENIED:
> > > + rc = -EACCES;
> > > + break;
> > > + case FFA_CRB_NOMEM:
> > > + rc = -ENOMEM;
> > > + break;
> > > + default:
> > > + rc = -EINVAL;
> > > + }
> > > +
> > > + return rc;
> > > +}
> > > +
> > > +int ffa_crb_init(void)
> > > +{
> > > + if (ffa_crb == NULL)
> > > + return -ENOENT;
> > > +
> > > + if (IS_ERR_VALUE(ffa_crb))
> > > + return -ENODEV;
> > > +
> > > + return 0;
> > > +}
> > > +EXPORT_SYMBOL_GPL(ffa_crb_init);
> > > +
> > > +static int __ffa_crb_send_recieve(unsigned long func_id,
> > > + unsigned long a0, unsigned long a1, unsigned long a2)
> > > +{
> > > + int ret;
> > > + const struct ffa_msg_ops *msg_ops;
> > > +
> > > + if (ffa_crb == NULL)
> > > + return -ENOENT;
> > > +
> > > + msg_ops = ffa_crb->ffa_dev->ops->msg_ops;
> > > +
> > > + memset(&ffa_crb->direct_msg_data, 0x00,
> > > + sizeof(struct ffa_send_direct_data));
> > > +
> > > + ffa_crb->direct_msg_data.data1 = func_id;
> > > + ffa_crb->direct_msg_data.data2 = a0;
> > > + ffa_crb->direct_msg_data.data3 = a1;
> > > + ffa_crb->direct_msg_data.data4 = a2;
> > > +
> > > + ret = msg_ops->sync_send_receive(ffa_crb->ffa_dev,
> > > + &ffa_crb->direct_msg_data);
> > > + if (!ret)
> > > + ret = ffa_crb_to_linux_errno(ffa_crb->direct_msg_data.data1);
> > > +
> > > + return ret;
> > > +}
> > > +
> > > +int ffa_crb_get_interface_version(uint16_t *major, uint16_t *minor)
> > > +{
> > > + int rc;
> > > +
> > > + if (ffa_crb == NULL)
> > > + return -ENOENT;
> > > +
> > > + if (IS_ERR_VALUE(ffa_crb))
> > > + return -ENODEV;
> > > +
> > > + if (major == NULL || minor == NULL)
> > > + return -EINVAL;
> > > +
> > > + guard(mutex)(&ffa_crb->msg_data_lock);
> > > +
> > > + rc = __ffa_crb_send_recieve(FFA_CRB_GET_INTERFACE_VERSION, 0x00, 0x00, 0x00);
> > > + if (!rc) {
> > > + *major = FFA_CRB_MAJOR_VERSION(ffa_crb->direct_msg_data.data2);
> > > + *minor = FFA_CRB_MINOR_VERSION(ffa_crb->direct_msg_data.data2);
> > > + }
> > > +
> > > + return rc;
> > > +}
> > > +EXPORT_SYMBOL_GPL(ffa_crb_get_interface_version);
> > > +
> > > +int ffa_crb_start(int request_type, int locality)
> > > +{
> > > + if (ffa_crb == NULL)
> > > + return -ENOENT;
> > > +
> > > + if (IS_ERR_VALUE(ffa_crb))
> > > + return -ENODEV;
> > > +
> > > + guard(mutex)(&ffa_crb->msg_data_lock);
> > > +
> > > + return __ffa_crb_send_recieve(FFA_CRB_START, request_type, locality, 0x00);
> > > +}
> > > +EXPORT_SYMBOL_GPL(ffa_crb_start);
> > > +
> > > +static int ffa_crb_probe(struct ffa_device *ffa_dev)
> > > +{
> > > + int rc;
> > > + struct ffa_crb *p;
> > > +
> > > + /* only one instance of a TPM partition is supported */
> > > + if (ffa_crb && !IS_ERR_VALUE(ffa_crb))
> > > + return -EEXIST;
> > > +
> > > + ffa_crb = ERR_PTR(-ENODEV); // set ffa_crb so we can detect probe failure
> > > +
> > > + if (!ffa_partition_supports_direct_recv(ffa_dev)) {
> > > + pr_err("TPM partition doesn't support direct message receive.\n");
> > > + return -EINVAL;
> > > + }
> > > +
> > > + p = kzalloc(sizeof(*ffa_crb), GFP_KERNEL);
> > > + if (!p)
> > > + return -ENOMEM;
> > > + ffa_crb = p;
> > > +
> > > + mutex_init(&ffa_crb->msg_data_lock);
> > > + ffa_crb->ffa_dev = ffa_dev;
> > > + ffa_dev_set_drvdata(ffa_dev, ffa_crb);
> > > +
> > > + /* if TPM is aarch32 use 32-bit SMCs */
> > > + if (!ffa_partition_check_property(ffa_dev, FFA_PARTITION_AARCH64_EXEC))
> > > + ffa_dev->ops->msg_ops->mode_32bit_set(ffa_dev);
> > > +
> > > + /* verify compatibility of TPM service version number */
> > > + rc = ffa_crb_get_interface_version(&ffa_crb->major_version,
> > > + &ffa_crb->minor_version);
> > > + if (rc) {
> > > + pr_err("failed to get crb interface version. rc:%d", rc);
> > > + goto out;
> > > + }
> > > +
> > > + pr_info("ABI version %u.%u", ffa_crb->major_version,
> > > + ffa_crb->minor_version);
> > > +
> > > + if ((ffa_crb->major_version != FFA_CRB_VERSION_MAJOR) ||
> > > + (ffa_crb->minor_version < FFA_CRB_VERSION_MINOR)) {
> > > + pr_err("Incompatible ABI version");
> > > + goto out;
> > > + }
> > > +
> > > + return 0;
> > > +
> > > +out:
> > > + kfree(ffa_crb);
> > > + ffa_crb = ERR_PTR(-ENODEV);
> > > + return -EINVAL;
> > > +}
> > > +
> > > +static void ffa_crb_remove(struct ffa_device *ffa_dev)
> > > +{
> > > + kfree(ffa_crb);
> > > + ffa_crb = NULL;
> > > +}
> > > +
> > > +static const struct ffa_device_id ffa_crb_device_id[] = {
> > > + /* 17b862a4-1806-4faf-86b3-089a58353861 */
> > > + { UUID_INIT(0x17b862a4, 0x1806, 0x4faf,
> > > + 0x86, 0xb3, 0x08, 0x9a, 0x58, 0x35, 0x38, 0x61) },
> > > + {}
> > > +};
> > > +
> > > +static struct ffa_driver ffa_crb_driver = {
> > > + .name = "ffa-crb",
> > > + .probe = ffa_crb_probe,
> > > + .remove = ffa_crb_remove,
> > > + .id_table = ffa_crb_device_id,
> > > +};
> > > +
> > > +module_ffa_driver(ffa_crb_driver);
> > > +
> > > +MODULE_AUTHOR("Arm");
> > > +MODULE_DESCRIPTION("FFA CRB driver");
> > > +MODULE_VERSION("1.0");
> > > +MODULE_LICENSE("GPL");
> > > diff --git a/drivers/char/tpm/tpm_ffa_crb.h b/drivers/char/tpm/tpm_ffa_crb.h
> > > new file mode 100644
> > > index 000000000000..42327d285165
> > > --- /dev/null
> > > +++ b/drivers/char/tpm/tpm_ffa_crb.h
> > > @@ -0,0 +1,30 @@
> > > +/* SPDX-License-Identifier: GPL-2.0-only */
> > > +/*
> > > + * Copyright (C) 2024 Arm Ltd.
> > > + *
> > > + * Authors:
> > > + * Stuart Yoder <stuart.yoder@....com>
> > > + *
> > > + * Maintained by: <tpmdd-devel@...ts.sourceforge.net>
> > > + *
> > > + * This device driver implements the TPM CRB start method
> > > + * as defined in the TPM Service Command Response Buffer
> > > + * Interface Over FF-A (DEN0138).
> > > + */
> > > +#ifndef _FFA_CRB_H
> > > +#define _FFA_CRB_H
> > > +
> > > +#if IS_ENABLED(CONFIG_TCG_ARM_FFA_CRB)
> > > +int ffa_crb_init(void);
> > > +int ffa_crb_get_interface_version(uint16_t *major, uint16_t *minor);
> > > +int ffa_crb_start(int request_type, int locality);
> > > +#else
> > > +static inline int ffa_crb_init(void) { return 0; }
> > > +static inline int ffa_crb_get_interface_version(uint16_t *major, uint16_t *minor) { return 0; }
> > > +static inline int ffa_crb_start(int request_type, int locality) { return 0; }
> > > +#endif
> > > +
> > > +#define FFA_CRB_START_TYPE_COMMAND 0
> > > +#define FFA_CRB_START_TYPE_LOCALITY_REQUEST 1
> > > +
> > > +#endif
> > > --
> > > 2.34.1
> > >
> > >
> >
> > tpm_crb_ffa_*
>
> I had renamed the source file to be tpm_ffa_crb.c based on your
> previous feedback. It would be good to be consistent. Would
> you prefer:
>
> tpm_crb_ffa_*
> or
> tpm_ffa_crb_*
I made a mistake and apologize for that!
I thought about tpm_crb_ffa_* but wrote in misorder.
Sorry about this!
BR, Jarkko
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