From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B296AC04AB6 for ; Tue, 14 May 2019 23:43:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7FD132084E for ; Tue, 14 May 2019 23:43:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726755AbfENXnA (ORCPT ); Tue, 14 May 2019 19:43:00 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:54374 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726669AbfENXm6 (ORCPT ); Tue, 14 May 2019 19:42:58 -0400 Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x4ENLtDG042043 for ; Tue, 14 May 2019 19:42:57 -0400 Received: from e06smtp05.uk.ibm.com (e06smtp05.uk.ibm.com [195.75.94.101]) by mx0a-001b2d01.pphosted.com with ESMTP id 2sg4n9xa9u-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 14 May 2019 19:42:56 -0400 Received: from localhost by e06smtp05.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 15 May 2019 00:42:53 +0100 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x4ENgq4l46268496 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 14 May 2019 23:42:52 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id EBC95AE055; Tue, 14 May 2019 23:42:51 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D1ED5AE04D; Tue, 14 May 2019 23:42:51 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.152.85.9]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Tue, 14 May 2019 23:42:51 +0000 (GMT) Received: by tuxmaker.boeblingen.de.ibm.com (Postfix, from userid 4958) id 399C8E15C7; Wed, 15 May 2019 01:42:51 +0200 (CEST) From: Eric Farman To: Cornelia Huck , Farhan Ali Cc: Halil Pasic , Pierre Morel , linux-s390@vger.kernel.org, kvm@vger.kernel.org, Eric Farman Subject: [PATCH v2 6/7] s390/cio: Don't pin vfio pages for empty transfers Date: Wed, 15 May 2019 01:42:47 +0200 X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190514234248.36203-1-farman@linux.ibm.com> References: <20190514234248.36203-1-farman@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 19051423-0020-0000-0000-0000033CB800 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19051423-0021-0000-0000-0000218F7681 Message-Id: <20190514234248.36203-7-farman@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-05-14_13:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=793 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905140153 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org If a CCW has a count of zero, then no data will be transferred and pinning/unpinning memory is unnecessary. In addition to that, the skip flag of a CCW offers the possibility of data not being transferred, but is only meaningful for certain commands. Specifically, it is only applicable for a read, read backward, sense, or sense ID CCW and will be ignored for any other command code (SA22-7832-11 page 15-64, and figure 15-30 on page 15-75). (A sense ID is xE4, while a sense is x04 with possible modifiers in the upper four bits. So we will cover the whole "family" of sense CCWs.) For all those scenarios, since there is no requirement for the target address to be valid, we should skip the call to vfio_pin_pages() and rely on the IDAL address we have allocated/built for the channel program. The fact that the individual IDAWs within the IDAL are invalid is fine, since they aren't actually checked in these cases. Set pa_nr to zero, when skipping the pfn_array_pin() call, since it is defined as the number of pages pinned. This will cause the vfio unpin logic to return -EINVAL, but since the return code is not checked it will not harm our cleanup path. As we do this, since the pfn_array_pin() routine returns the number of pages pinned, and we might not be doing that, the logic for converting a CCW from direct-addressed to IDAL needs to ensure there is room for one IDAW in the IDAL being built since a zero-length IDAL isn't great. Signed-off-by: Eric Farman --- drivers/s390/cio/vfio_ccw_cp.c | 61 ++++++++++++++++++++++++++++++---- 1 file changed, 55 insertions(+), 6 deletions(-) diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c index a68711114aab..94888094ed2c 100644 --- a/drivers/s390/cio/vfio_ccw_cp.c +++ b/drivers/s390/cio/vfio_ccw_cp.c @@ -291,6 +291,10 @@ static long copy_ccw_from_iova(struct channel_program *cp, /* * Helpers to operate ccwchain. */ +#define ccw_is_read(_ccw) (((_ccw)->cmd_code & 0x03) == 0x02) +#define ccw_is_read_backward(_ccw) (((_ccw)->cmd_code & 0x0F) == 0x0C) +#define ccw_is_sense(_ccw) (((_ccw)->cmd_code & 0x0F) == CCW_CMD_BASIC_SENSE) + #define ccw_is_test(_ccw) (((_ccw)->cmd_code & 0x0F) == 0) #define ccw_is_noop(_ccw) ((_ccw)->cmd_code == CCW_CMD_NOOP) @@ -298,10 +302,43 @@ static long copy_ccw_from_iova(struct channel_program *cp, #define ccw_is_tic(_ccw) ((_ccw)->cmd_code == CCW_CMD_TIC) #define ccw_is_idal(_ccw) ((_ccw)->flags & CCW_FLAG_IDA) - +#define ccw_is_skip(_ccw) ((_ccw)->flags & CCW_FLAG_SKIP) #define ccw_is_chain(_ccw) ((_ccw)->flags & (CCW_FLAG_CC | CCW_FLAG_DC)) +/* + * ccw_does_data_transfer() + * + * Determine whether a CCW will move any data, such that the guest pages + * would need to be pinned before performing the I/O. + * + * Returns 1 if yes, 0 if no. + */ +static inline int ccw_does_data_transfer(struct ccw1 *ccw) +{ + /* If the count field is zero, then no data will be transferred */ + if (ccw->count == 0) + return 0; + + /* If the skip flag is off, then data will be transferred */ + if (!ccw_is_skip(ccw)) + return 1; + + /* + * If the skip flag is on, it is only meaningful if the command + * code is a read, read backward, sense, or sense ID. In those + * cases, no data will be transferred. + */ + if (ccw_is_read(ccw) || ccw_is_read_backward(ccw)) + return 0; + + if (ccw_is_sense(ccw)) + return 0; + + /* The skip flag is on, but it is ignored for this command code. */ + return 1; +} + /* * is_cpa_within_range() * @@ -554,11 +591,14 @@ static int ccwchain_fetch_direct(struct ccwchain *chain, unsigned long *idaws; int ret; int bytes = 1; + int idaw_nr = 1; ccw = chain->ch_ccw + idx; - if (ccw->count) + if (ccw->count) { bytes = ccw->count; + idaw_nr = idal_nr_words((void *)(u64)ccw->cda, ccw->count); + } /* * Pin data page(s) in memory. @@ -574,12 +614,16 @@ static int ccwchain_fetch_direct(struct ccwchain *chain, if (ret < 0) goto out_unpin; - ret = pfn_array_pin(pat->pat_pa, cp->mdev); - if (ret < 0) - goto out_unpin; + if (ccw_does_data_transfer(ccw)) { + ret = pfn_array_pin(pat->pat_pa, cp->mdev); + if (ret < 0) + goto out_unpin; + } else { + pat->pat_pa->pa_nr = 0; + } /* Translate this direct ccw to a idal ccw. */ - idaws = kcalloc(ret, sizeof(*idaws), GFP_DMA | GFP_KERNEL); + idaws = kcalloc(idaw_nr, sizeof(*idaws), GFP_DMA | GFP_KERNEL); if (!idaws) { ret = -ENOMEM; goto out_unpin; @@ -650,6 +694,11 @@ static int ccwchain_fetch_idal(struct ccwchain *chain, if (ret < 0) goto out_free_idaws; + if (!ccw_does_data_transfer(ccw)) { + pa->pa_nr = 0; + continue; + } + ret = pfn_array_pin(pa, cp->mdev); if (ret < 0) goto out_free_idaws; -- 2.17.1