From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752632AbeDRPCB (ORCPT ); Wed, 18 Apr 2018 11:02:01 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:5854 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751204AbeDRPB7 (ORCPT ); Wed, 18 Apr 2018 11:01:59 -0400 Subject: Re: [PATCH v2 1/2] tpm: reduce poll sleep time in tpm_transmit() From: Mimi Zohar To: Nayna Jain , linux-integrity@vger.kernel.org Cc: 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 Date: Wed, 18 Apr 2018 11:01:48 -0400 In-Reply-To: <20180417131246.434-2-nayna@linux.vnet.ibm.com> References: <20180417131246.434-1-nayna@linux.vnet.ibm.com> <20180417131246.434-2-nayna@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.20.5 (3.20.5-1.fc24) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 18041815-0012-0000-0000-000005CC463C X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18041815-0013-0000-0000-000019489845 Message-Id: <1524063708.3272.301.camel@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-04-18_03:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1804180135 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2018-04-17 at 09:12 -0400, Nayna Jain wrote: > The TPM polling code in tpm_transmit sleeps in each loop iteration for > 5 msecs. However, the TPM might return earlier, and thus waiting for > 5 msecs adds an unnecessary delay. This patch reduces the polling sleep > time in tpm_transmit() from 5 msecs to 1 msecs. > > Additionally, this patch renames TPM_POLL_SLEEP and moves it to tpm.h as > an enum value. > > After this change, performance on a TPM 1.2 with an 8 byte burstcount > for 1000 extends improved from ~14 sec to ~10.7 sec. > > Signed-off-by: Nayna Jain Reviewed-by: Mimi Zohar > --- > drivers/char/tpm/tpm-interface.c | 2 +- > drivers/char/tpm/tpm.h | 3 ++- > drivers/char/tpm/tpm_tis_core.c | 10 ++-------- > 3 files changed, 5 insertions(+), 10 deletions(-) > > diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c > index 9e80a953d693..a676d8ad5992 100644 > --- a/drivers/char/tpm/tpm-interface.c > +++ b/drivers/char/tpm/tpm-interface.c > @@ -470,7 +470,7 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space, > goto out; > } > > - tpm_msleep(TPM_TIMEOUT); > + tpm_msleep(TPM_TIMEOUT_POLL); > rmb(); > } while (time_before(jiffies, stop)); > > diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h > index f895fba4e20d..7e797377e1eb 100644 > --- a/drivers/char/tpm/tpm.h > +++ b/drivers/char/tpm/tpm.h > @@ -53,7 +53,8 @@ enum tpm_const { > enum tpm_timeout { > TPM_TIMEOUT = 5, /* msecs */ > TPM_TIMEOUT_RETRY = 100, /* msecs */ > - TPM_TIMEOUT_RANGE_US = 300 /* usecs */ > + TPM_TIMEOUT_RANGE_US = 300, /* usecs */ > + TPM_TIMEOUT_POLL = 1 /* msecs */ > }; > > /* TPM addresses */ > diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c > index da074e3db19b..021e6b68f2db 100644 > --- a/drivers/char/tpm/tpm_tis_core.c > +++ b/drivers/char/tpm/tpm_tis_core.c > @@ -31,12 +31,6 @@ > #include "tpm.h" > #include "tpm_tis_core.h" > > -/* This is a polling delay to check for status and burstcount. > - * As per ddwg input, expectation is that status check and burstcount > - * check should return within few usecs. > - */ > -#define TPM_POLL_SLEEP 1 /* msec */ > - > static void tpm_tis_clkrun_enable(struct tpm_chip *chip, bool value); > > static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask, > @@ -90,7 +84,7 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, > } > } else { > do { > - tpm_msleep(TPM_POLL_SLEEP); > + tpm_msleep(TPM_TIMEOUT_POLL); > status = chip->ops->status(chip); > if ((status & mask) == mask) > return 0; > @@ -232,7 +226,7 @@ static int get_burstcount(struct tpm_chip *chip) > burstcnt = (value >> 8) & 0xFFFF; > if (burstcnt) > return burstcnt; > - tpm_msleep(TPM_POLL_SLEEP); > + tpm_msleep(TPM_TIMEOUT_POLL); > } while (time_before(jiffies, stop)); > return -EBUSY; > }