From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756623AbdJKLaD (ORCPT ); Wed, 11 Oct 2017 07:30:03 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:53053 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752099AbdJKL37 (ORCPT ); Wed, 11 Oct 2017 07:29:59 -0400 Subject: Re: [PATCH v3 2/5] tpm: ignore burstcount to improve tpm_tis send() performance To: Jarkko Sakkinen Cc: linux-integrity@vger.kernel.org, zohar@linux.vnet.ibm.com, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, peterhuewe@gmx.de, tpmdd@selhorst.net, jgunthorpe@obsidianresearch.com, patrickc@us.ibm.com References: <20171004102924.12355-1-nayna@linux.vnet.ibm.com> <20171004102924.12355-3-nayna@linux.vnet.ibm.com> <20171010150433.vxwxg4wzc3lgqckf@linux.intel.com> From: Nayna Jain Date: Wed, 11 Oct 2017 16:59:30 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: <20171010150433.vxwxg4wzc3lgqckf@linux.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-TM-AS-GCONF: 00 x-cbid: 17101111-0008-0000-0000-000008B247F0 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007878; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000235; SDB=6.00929559; UDB=6.00467862; IPR=6.00709830; BA=6.00005634; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00017488; XFM=3.00000015; UTC=2017-10-11 11:29:55 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17101111-0009-0000-0000-00004450F6B6 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-10-11_02:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000 definitions=main-1710110159 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/10/2017 08:34 PM, Jarkko Sakkinen wrote: > On Wed, Oct 04, 2017 at 06:29:21AM -0400, Nayna Jain wrote: >> 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); > Otherwise, this looks good but I don't understand why you assign 'len - > 1' to 'brustcnt' and pass it to tpm_tis_write_bytes() instead of just > passing 'len - 1'. I mean no relation to burst count, right? Yeah, I can just send 'len - 1'. Will do this change. Thanks & Regards,      - Nayna > > /Jarkko >