linux-kernel - Re: [PATCH v2 2/3] ftpm: firmware TPM running in TEE

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Message-ID: <20190409192240.GA12869@ziepe.ca>
Date:   Tue, 9 Apr 2019 16:22:40 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Sasha Levin <sashal@...nel.org>
Cc:     peterhuewe@....de, jarkko.sakkinen@...ux.intel.com,
        mark.rutland@....com, corbet@....net, robh+dt@...nel.org,
        arnd@...db.de, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-integrity@...r.kernel.org, linux-kernel@...rosoft.com,
        thiruan@...rosoft.com, bryankel@...rosoft.com
Subject: Re: [PATCH v2 2/3] ftpm: firmware TPM running in TEE

On Tue, Apr 09, 2019 at 02:49:57PM -0400, Sasha Levin wrote:

> +/*
> + * Undo what has been done in ftpm_tee_probe
> + */
> +static void ftpm_tee_deinit(struct ftpm_tee_private *pvt_data)
> +{
> +	/* Release the chip */
> +	tpm_chip_unregister(pvt_data->chip);
> +
> +	/* frees chip */
> +	if (pvt_data->chip)
> +		put_device(&pvt_data->chip->dev);
> +
> +	if (pvt_data->ctx) {
> +		/* Free the shared memory pool */
> +		tee_shm_free(pvt_data->shm);
> +
> +		/* close the existing session with fTPM TA*/
> +		tee_client_close_session(pvt_data->ctx, pvt_data->session);
> +
> +		/* close the context with TEE driver */
> +		tee_client_close_context(pvt_data->ctx);
> +	}

None of these if's are necessary, remove is only called if probe
succeeds. Would also make more sense to put this code into remove
instead of having it call one function..

> diff --git a/drivers/char/tpm/tpm_ftpm_tee.h b/drivers/char/tpm/tpm_ftpm_tee.h
> new file mode 100644
> index 000000000000..c1dd416d27c9
> +++ b/drivers/char/tpm/tpm_ftpm_tee.h
> @@ -0,0 +1,52 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) Microsoft Corporation
> + */
> +
> +#ifndef __TPM_FTPM_TEE_H__
> +#define __TPM_FTPM_TEE_H__
> +
> +#include <linux/tee_drv.h>
> +#include <linux/uuid.h>
> +#include <linux/tpm.h>
> +
> +/* The TAFs ID implemented in this TA */
> +#define FTPM_OPTEE_TA_SUBMIT_COMMAND  (0)
> +#define FTPM_OPTEE_TA_EMULATE_PPI     (1)
> +
> +/* max. buffer size supported by fTPM  */
> +#define  MAX_COMMAND_SIZE       4096
> +#define  MAX_RESPONSE_SIZE      4096
> +
> +/**
> + * struct ftpm_tee_private - fTPM's private data
> + * @chip:     struct tpm_chip instance registered with tpm framework.
> + * @state:    internal state
> + * @session:  fTPM TA session identifier.
> + * @resp_len: cached response buffer length.
> + * @resp_buf: cached response buffer.
> + * @ctx:      TEE context handler.
> + * @shm:      Memory pool shared with fTPM TA in TEE.
> + */
> +struct ftpm_tee_private {
> +	struct tpm_chip *chip;
> +	u32 session;
> +	size_t resp_len;
> +	u8 resp_buf[MAX_RESPONSE_SIZE];
> +	struct tee_context *ctx;
> +	struct tee_shm *shm;
> +};
> +
> +/*
> + * Note: ftpm_tee_tpm_op_recv and ftpm_tee_tpm_op_send are called from the
> + * same routine tpm_try_transmit in tpm-interface.c. These calls are protected
> + * by chip->tpm_mutex => There is no need for protecting any data shared
> + * between these routines ex: struct ftpm_tee_private
> + */
> +
> +/* TA_FTPM_UUID: BC50D971-D4C9-42C4-82CB-343FB7F37896 */
> +static const uuid_t ftpm_ta_uuid =
> +	UUID_INIT(0xBC50D971, 0xD4C9, 0x42C4,
> +		  0x82, 0xCB, 0x34, 0x3F, 0xB7, 0xF3, 0x78, 0x96);

Don't put static variables in header files

Jason