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Fri, 31 Jan 2020 20:15:03 +0000 Received: from b01ledav006.gho.pok.ibm.com (b01ledav006.gho.pok.ibm.com [9.57.199.111]) by b01cxnp23032.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 00VKF3Lv45547790 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 31 Jan 2020 20:15:03 GMT Received: from b01ledav006.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 554F8AC060; Fri, 31 Jan 2020 20:15:01 +0000 (GMT) Received: from b01ledav006.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CF68FAC05E; Fri, 31 Jan 2020 20:15:00 +0000 (GMT) Received: from [9.160.119.184] (unknown [9.160.119.184]) by b01ledav006.gho.pok.ibm.com (Postfix) with ESMTP; Fri, 31 Jan 2020 20:15:00 +0000 (GMT) Subject: Re: [RFC PATCH v1 5/8] vfio-ccw: Add support for the schib region To: Cornelia Huck References: <20191115033437.37926-1-farman@linux.ibm.com> <20191115033437.37926-6-farman@linux.ibm.com> <20191120121329.73dbddc2.cohuck@redhat.com> From: Eric Farman Message-ID: <70370f47-b36b-d36a-c8b7-f7cace7f47b4@linux.ibm.com> Date: Fri, 31 Jan 2020 15:15:00 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <20191120121329.73dbddc2.cohuck@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.572 definitions=2020-01-31_06:2020-01-31, 2020-01-31 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 phishscore=0 impostorscore=0 mlxscore=0 clxscore=1011 spamscore=0 mlxlogscore=999 bulkscore=0 lowpriorityscore=0 adultscore=0 malwarescore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1911200001 definitions=main-2001310169 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] X-Received-From: 148.163.158.5 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Halil Pasic , Jason Herne , qemu-s390x@nongnu.org, qemu-devel@nongnu.org, Jared Rossi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" [Had two un-addressed QEMU comments on my todo list; let's do that now.] On 11/20/19 6:13 AM, Cornelia Huck wrote: > On Fri, 15 Nov 2019 04:34:34 +0100 > Eric Farman wrote: > >> From: Farhan Ali >> >> The schib region can be used to obtain the latest SCHIB from the host >> passthrough subchannel. Since the guest SCHIB is virtualized, >> we currently only update the path related information so that the >> guest is aware of any path related changes when it issues the >> 'stsch' instruction. > > One important information here is that you tweak the generic stsch > handling, although the behaviour remains the same for non-vfio > subchannels. > >> >> Signed-off-by: Farhan Ali >> Signed-off-by: Eric Farman >> --- >> >> Notes: >> v0->v1: [EF] >> - Change various incarnations of "update chp status" to >> "handle_store", to reflect the STSCH instruction that will >> drive this code >> - Remove temporary variable for casting/testing purposes in >> s390_ccw_store(), and add a block comment of WHY its there. >> - Add a few comments to vfio_ccw_handle_store() >> >> hw/s390x/css.c | 8 ++++-- >> hw/s390x/s390-ccw.c | 20 +++++++++++++ >> hw/vfio/ccw.c | 57 +++++++++++++++++++++++++++++++++++++ >> include/hw/s390x/css.h | 3 +- >> include/hw/s390x/s390-ccw.h | 1 + >> target/s390x/ioinst.c | 3 +- >> 6 files changed, 87 insertions(+), 5 deletions(-) >> >> diff --git a/hw/s390x/css.c b/hw/s390x/css.c >> index 844caab408..6ee6a96d75 100644 >> --- a/hw/s390x/css.c >> +++ b/hw/s390x/css.c >> @@ -1335,11 +1335,15 @@ static void copy_schib_to_guest(SCHIB *dest, const SCHIB *src) >> } >> } >> >> -int css_do_stsch(SubchDev *sch, SCHIB *schib) >> +IOInstEnding css_do_stsch(SubchDev *sch, SCHIB *schib) >> { >> + int ret = IOINST_CC_EXPECTED; > > It's a bit useless initializing ret here, given that you use it right > below :) > >> + > > Maybe add a comment here: > > /* > * For some subchannels, we may want to update parts of > * the schib (e.g. update path masks from the host device > * for passthrough subchannels). > */ > >> + ret = s390_ccw_store(sch); >> + >> /* Use current status. */ >> copy_schib_to_guest(schib, &sch->curr_status); >> - return 0; >> + return ret; >> } >> >> static void copy_pmcw_from_guest(PMCW *dest, const PMCW *src) >> diff --git a/hw/s390x/s390-ccw.c b/hw/s390x/s390-ccw.c >> index 0c5a5b60bd..be0b379338 100644 >> --- a/hw/s390x/s390-ccw.c >> +++ b/hw/s390x/s390-ccw.c >> @@ -51,6 +51,26 @@ int s390_ccw_clear(SubchDev *sch) >> return cdc->handle_clear(sch); >> } >> >> +IOInstEnding s390_ccw_store(SubchDev *sch) >> +{ >> + S390CCWDeviceClass *cdc = NULL; >> + int ret = IOINST_CC_EXPECTED; >> + >> + /* >> + * This only applies to passthrough devices, so we can't unconditionally >> + * set this variable like we would for halt/clear. > > Hm, can we maybe handle this differently? We have a generic ccw_cb in > the subchannel structure for ccw interpretation; would it make sense to > add a generic callback for stsch there as well? Might make things a little cleaner, but I am not sure. I'm going to leave a todo here while we sort out the rest of the kernel code, so I can try to put something more beneficial together. > > (This works fine, though. Might want to add the check for halt/clear as > well, but that might be a bit overkill.) > >> + */ >> + if (object_dynamic_cast(OBJECT(sch->driver_data), TYPE_S390_CCW)) { >> + cdc = S390_CCW_DEVICE_GET_CLASS(sch->driver_data); >> + } >> + >> + if (cdc && cdc->handle_store) { >> + ret = cdc->handle_store(sch); >> + } >> + >> + return ret; >> +} >> + >> static void s390_ccw_get_dev_info(S390CCWDevice *cdev, >> char *sysfsdev, >> Error **errp) >> diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c >> index 3e32bc1819..2ff223470f 100644 >> --- a/hw/vfio/ccw.c >> +++ b/hw/vfio/ccw.c >> @@ -41,6 +41,9 @@ struct VFIOCCWDevice { >> uint64_t async_cmd_region_size; >> uint64_t async_cmd_region_offset; >> struct ccw_cmd_region *async_cmd_region; >> + uint64_t schib_region_size; >> + uint64_t schib_region_offset; >> + struct ccw_schib_region *schib_region; >> EventNotifier io_notifier; >> bool force_orb_pfch; >> bool warned_orb_pfch; >> @@ -124,6 +127,45 @@ again: >> } >> } >> >> +static IOInstEnding vfio_ccw_handle_store(SubchDev *sch) >> +{ >> + S390CCWDevice *cdev = sch->driver_data; >> + VFIOCCWDevice *vcdev = DO_UPCAST(VFIOCCWDevice, cdev, cdev); >> + SCHIB *schib = &sch->curr_status; >> + struct ccw_schib_region *region = vcdev->schib_region; >> + SCHIB *s = (SCHIB *)region->schib_area; > > You probably don't want to access region until after you checked it's > not NULL :) :) > >> + int ret; >> + >> + /* schib region not available so nothing else to do */ >> + if (!region) { >> + return IOINST_CC_EXPECTED; >> + } >> + >> + memset(region, 0, sizeof(*region)); >> + ret = pread(vcdev->vdev.fd, region, vcdev->schib_region_size, >> + vcdev->schib_region_offset); >> + >> + if (ret == -1) { >> + /* Assume device is damaged, regardless of errno */ >> + return IOINST_CC_NOT_OPERATIONAL; > > Not sure that's correct; cc 3 for stsch indicates that there are no > more subchannels with higher ids? POPS says cc=3 on stsch if the subchannel is not operational, and it's not operational if it's not provided to the channel subsystem. So, basically yes. I guess his idea was to call out a problem on the kvm side, so should we just return CC_EXPECTED here, as if there's no region? > >> + } >> + >> + /* >> + * Selectively copy path-related bits of the SCHIB, >> + * rather than copying the entire struct. >> + */ >> + schib->pmcw.pnom = s->pmcw.pnom; >> + schib->pmcw.lpum = s->pmcw.lpum; >> + schib->pmcw.pam = s->pmcw.pam; >> + schib->pmcw.pom = s->pmcw.pom; >> + >> + if (s->scsw.flags & SCSW_FLAGS_MASK_PNO) { >> + schib->scsw.flags |= SCSW_FLAGS_MASK_PNO; >> + } >> + >> + return IOINST_CC_EXPECTED; >> +} >> + > > The rest of the patch looks good to me. >