From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38344) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d5sF3-0004pL-33 for qemu-devel@nongnu.org; Wed, 03 May 2017 07:14:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d5sEz-0000YO-TR for qemu-devel@nongnu.org; Wed, 03 May 2017 07:14:45 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:43873 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1d5sEz-0000Y8-O0 for qemu-devel@nongnu.org; Wed, 03 May 2017 07:14:41 -0400 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v43BE3ag048489 for ; Wed, 3 May 2017 07:14:40 -0400 Received: from e06smtp15.uk.ibm.com (e06smtp15.uk.ibm.com [195.75.94.111]) by mx0b-001b2d01.pphosted.com with ESMTP id 2a7b7f0dxx-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 03 May 2017 07:14:40 -0400 Received: from localhost by e06smtp15.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 3 May 2017 12:14:37 +0100 Date: Wed, 3 May 2017 13:14:32 +0200 From: Cornelia Huck In-Reply-To: <20170503021850.GG27968@bjsdjshi@linux.vnet.ibm.com> References: <20170428130951.44771-1-bjsdjshi@linux.vnet.ibm.com> <20170428130951.44771-11-bjsdjshi@linux.vnet.ibm.com> <6a3e0621-9e16-ddd4-c1d9-2a7351ebb9e6@redhat.com> <20170502021519.GA27968@bjsdjshi@linux.vnet.ibm.com> <20170502180407.33a8f468.cornelia.huck@de.ibm.com> <20170503021850.GG27968@bjsdjshi@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-Id: <20170503131432.1a2ecf40.cornelia.huck@de.ibm.com> Subject: Re: [Qemu-devel] [PATCH v6 10/13] s390x/css: introduce and realize ccw-request callback List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Dong Jia Shi Cc: linux-s390@vger.kernel.org, kvm@vger.kernel.org, borntraeger@de.ibm.com, qemu-devel@nongnu.org, Auger Eric , alex.williamson@redhat.com, Xiao Feng Ren , agraf@suse.com On Wed, 3 May 2017 10:18:50 +0800 Dong Jia Shi wrote: > * Cornelia Huck [2017-05-02 18:04:07 +0200]: > > > On Tue, 2 May 2017 10:15:19 +0800 > > Dong Jia Shi wrote: > > > > > * Auger Eric [2017-05-01 19:28:23 +0200]: > > > > > > > static void vfio_ccw_io_notifier_handler(void *opaque) > > > > > { > > > > > VFIOCCWDevice *vcdev = opaque; > > > > > + struct ccw_io_region *region = vcdev->io_region; > > > > > + S390CCWDevice *cdev = S390_CCW_DEVICE(vcdev); > > > > > + CcwDevice *ccw_dev = CCW_DEVICE(cdev); > > > > > + SubchDev *sch = ccw_dev->sch; > > > > > + SCSW *s = &sch->curr_status.scsw; > > > > > + IRB irb; > > > > > > > > > > if (!event_notifier_test_and_clear(&vcdev->io_notifier)) { > > > > > return; > > > > > } > > > > > + > > > > > + if (pread(vcdev->vdev.fd, region, > > > > > + vcdev->io_region_size, vcdev->io_region_offset) == -1) { > > > > is it possible to read less bytes than requested? > > > Currently, impossible. The kernel side returns either the full region, > > > or an error. > > > But we surely could make it more friendly for a partial return. I will > > > add a check for that case, and generate a channel program check for it. > > > > I think a channel-control check would be more appropriate here. > > Hi Conny, > > After reading PoP 14-43, I think you are right. (...) > So I decide to add this piece of code: > if (size != vcdev->io_region_size) { > /* Information transfer error, generate channel-control check. */ > s->ctrl &= ~SCSW_ACTL_START_PEND; > s->cstat = SCSW_CSTAT_CHN_CTRL_CHK; > s->ctrl &= ~SCSW_CTRL_MASK_STCTL; > s->ctrl |= SCSW_STCTL_PRIMARY | SCSW_STCTL_SECONDARY | > SCSW_STCTL_ALERT | SCSW_STCTL_STATUS_PEND; > goto read_err; > } Looks good.