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=-6.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 E4EE9C33CAC for ; Mon, 3 Feb 2020 10:43:53 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AE6EF20661 for ; Mon, 3 Feb 2020 10:43:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BCojKYW4" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AE6EF20661 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:37734 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iyZCq-0008Ss-RX for qemu-devel@archiver.kernel.org; Mon, 03 Feb 2020 05:43:52 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:48583) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iyZCH-0007xC-Lt for qemu-devel@nongnu.org; Mon, 03 Feb 2020 05:43:19 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iyZCG-0005Kk-6t for qemu-devel@nongnu.org; Mon, 03 Feb 2020 05:43:17 -0500 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:48646 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iyZCF-0005Jb-Qi for qemu-devel@nongnu.org; Mon, 03 Feb 2020 05:43:16 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1580726595; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0G0MrmAiruKjFt5vLzFIt8vi8JLTjhD/YZjyKBVbm4o=; b=BCojKYW4Iwqe/3iF6JUatBzZrX64zGGtYTLT+ZXUx5x4x1bwbHhVVlz4wa7eDBFctUQ292 W5dCtSFbr/eApUCEz8gWV8ccukyipXp1QFu2Ahuh/A+xF7+8g1dnSL93ol60opikyE/Qj8 HeQujJq+vPMy2f2rEo8Rle3zMoSkXEk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-327-fRkHbrLWOB2KYGitM8hjEw-1; Mon, 03 Feb 2020 05:43:11 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A162D107ACC7; Mon, 3 Feb 2020 10:43:09 +0000 (UTC) Received: from gondolin (ovpn-117-79.ams2.redhat.com [10.36.117.79]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4669B89A82; Mon, 3 Feb 2020 10:43:08 +0000 (UTC) Date: Mon, 3 Feb 2020 11:43:05 +0100 From: Cornelia Huck To: Eric Farman Subject: Re: [RFC PATCH v1 5/8] vfio-ccw: Add support for the schib region Message-ID: <20200203114305.7fd301c0.cohuck@redhat.com> In-Reply-To: <70370f47-b36b-d36a-c8b7-f7cace7f47b4@linux.ibm.com> References: <20191115033437.37926-1-farman@linux.ibm.com> <20191115033437.37926-6-farman@linux.ibm.com> <20191120121329.73dbddc2.cohuck@redhat.com> <70370f47-b36b-d36a-c8b7-f7cace7f47b4@linux.ibm.com> Organization: Red Hat GmbH MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: fRkHbrLWOB2KYGitM8hjEw-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 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" On Fri, 31 Jan 2020 15:15:00 -0500 Eric Farman wrote: > [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: Oh, that was some time ago... hope I can still recall what I was thinking back then. > > > >> 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. Yes, this looks like something that can be sorted out later. What bothers me most here, I guess, is that it is not very obvious why the functions above can assume the presence of the cdc object, while this one can't. The secret sauce is in the different do_subchannel_work_* callbacks, which reside in another file... maybe amend the comment here to mention that? That would help and doesn't involve code refactoring :) > > > > > (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? Yes, that looks like the better choice (out of the two possible condition codes...) And also log a moan somewhere? > > > > >> + } > >> + > >> + /* > >> + * 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. > > >