From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:59340 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751385AbdJDK3x (ORCPT ); Wed, 4 Oct 2017 06:29:53 -0400 Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v94ATALB140527 for ; Wed, 4 Oct 2017 06:29:53 -0400 Received: from e23smtp04.au.ibm.com (e23smtp04.au.ibm.com [202.81.31.146]) by mx0a-001b2d01.pphosted.com with ESMTP id 2dcvyxucfe-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 04 Oct 2017 06:29:52 -0400 Received: from localhost by e23smtp04.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 4 Oct 2017 20:29:50 +1000 From: Nayna Jain To: linux-integrity@vger.kernel.org Cc: zohar@linux.vnet.ibm.com, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, peterhuewe@gmx.de, jarkko.sakkinen@linux.intel.com, tpmdd@selhorst.net, jgunthorpe@obsidianresearch.com, patrickc@us.ibm.com, Nayna Jain Subject: [PATCH v3 2/5] tpm: ignore burstcount to improve tpm_tis send() performance Date: Wed, 4 Oct 2017 06:29:21 -0400 In-Reply-To: <20171004102924.12355-1-nayna@linux.vnet.ibm.com> References: <20171004102924.12355-1-nayna@linux.vnet.ibm.com> Message-Id: <20171004102924.12355-3-nayna@linux.vnet.ibm.com> Sender: linux-integrity-owner@vger.kernel.org List-ID: The TPM burstcount status indicates the number of bytes that can be sent to the TPM without causing bus wait states. Effectively, it is the number of empty bytes in the command FIFO. Further, some TPMs have a static burstcount, when the value remains zero until the entire FIFO is empty. This patch optimizes the tpm_tis_send_data() function by checking the burstcount only once. And if the burstcount is valid, it writes all the bytes at once, permitting wait states. The performance of a 34 byte extend on a TPM 1.2 with an 8 byte burstcount improved from 41msec to 14msec. After this change, performance on a TPM 1.2 with an 8 byte burstcount for 1000 extends improved from ~41sec to ~14sec. Suggested-by: Ken Goldman in conjunction with the TPM Device Driver work group. Signed-off-by: Nayna Jain Acked-by: Mimi Zohar --- drivers/char/tpm/tpm_tis_core.c | 42 ++++++++++++++++------------------------- 1 file changed, 16 insertions(+), 26 deletions(-) diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index b33126a35694..8da425e1783f 100644 --- a/drivers/char/tpm/tpm_tis_core.c +++ b/drivers/char/tpm/tpm_tis_core.c @@ -316,7 +316,6 @@ static int tpm_tis_send_data(struct tpm_chip *chip, u8 *buf, size_t len) { struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev); int rc, status, burstcnt; - size_t count = 0; bool itpm = priv->flags & TPM_TIS_ITPM_WORKAROUND; status = tpm_tis_status(chip); @@ -330,35 +329,26 @@ static int tpm_tis_send_data(struct tpm_chip *chip, u8 *buf, size_t len) } } - while (count < len - 1) { - burstcnt = get_burstcount(chip); - if (burstcnt < 0) { - dev_err(&chip->dev, "Unable to read burstcount\n"); - rc = burstcnt; - goto out_err; - } - burstcnt = min_t(int, burstcnt, len - count - 1); - rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality), - burstcnt, buf + count); - if (rc < 0) - goto out_err; + /* + * Get the initial burstcount to ensure TPM is ready to + * accept data. + */ + burstcnt = get_burstcount(chip); + if (burstcnt < 0) { + dev_err(&chip->dev, "Unable to read burstcount\n"); + rc = burstcnt; + goto out_err; + } - count += burstcnt; + burstcnt = len - 1; - if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c, - &priv->int_queue, false) < 0) { - rc = -ETIME; - goto out_err; - } - status = tpm_tis_status(chip); - if (!itpm && (status & TPM_STS_DATA_EXPECT) == 0) { - rc = -EIO; - goto out_err; - } - } + rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality), + burstcnt, buf); + if (rc < 0) + goto out_err; /* write last byte */ - rc = tpm_tis_write8(priv, TPM_DATA_FIFO(priv->locality), buf[count]); + rc = tpm_tis_write8(priv, TPM_DATA_FIFO(priv->locality), buf[len-1]); if (rc < 0) goto out_err; -- 2.13.3