From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53918) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dVe0i-0005Ut-NM for qemu-devel@nongnu.org; Thu, 13 Jul 2017 09:18:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dVe0f-00054h-Ix for qemu-devel@nongnu.org; Thu, 13 Jul 2017 09:18:28 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:48755 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 1dVe0f-00054N-Ci for qemu-devel@nongnu.org; Thu, 13 Jul 2017 09:18:25 -0400 Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v6DDDeZk117972 for ; Thu, 13 Jul 2017 09:18:24 -0400 Received: from e06smtp15.uk.ibm.com (e06smtp15.uk.ibm.com [195.75.94.111]) by mx0b-001b2d01.pphosted.com with ESMTP id 2bnt3m80k8-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 13 Jul 2017 09:18:24 -0400 Received: from localhost by e06smtp15.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 13 Jul 2017 14:18:22 +0100 References: <1499942429-55449-1-git-send-email-borntraeger@de.ibm.com> <1499942429-55449-4-git-send-email-borntraeger@de.ibm.com> <20170713142721.3a40e083@gondolin> From: Halil Pasic Date: Thu, 13 Jul 2017 15:18:18 +0200 MIME-Version: 1.0 In-Reply-To: <20170713142721.3a40e083@gondolin> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Message-Id: <1798a9f2-63f0-ab03-11ad-5513d9a90da9@linux.vnet.ibm.com> Subject: Re: [Qemu-devel] [PATCH/s390-next 3/3] s390x/flic: migrate ais states List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Cornelia Huck , Christian Borntraeger , "Dr . David Alan Gilbert" , Juan Quintela Cc: Yi Min Zhao , Pierre Morel , qemu-devel , Alexander Graf , Thomas Huth , Richard Henderson On 07/13/2017 02:27 PM, Cornelia Huck wrote: >> +static void kvm_flic_ais_pre_save(void *opaque) >> +{ >> + KVMS390FLICStateMigTmp *tmp = opaque; >> + KVMS390FLICState *flic = tmp->parent; >> + struct kvm_s390_ais_all ais; >> + struct kvm_device_attr attr = { >> + .group = KVM_DEV_FLIC_AISM_ALL, >> + .addr = (uint64_t)&ais, >> + .attr = sizeof(ais), >> + }; >> + >> + if (ioctl(flic->fd, KVM_GET_DEVICE_ATTR, &attr)) { >> + error_report("Failed to retrieve kvm flic ais states"); > There's not much else we can do in that case, is there? > I think this is a very good question! The ioctl should not fail under any circumstances, but if it does we have a problem. Carrying on happily (what we do now) means effectively discarding ais state. In general just discarding state ain't a good idea. In particular it might be OK, but the patch should explain that! Regarding what could/should we do in such a case (instead of discarding state and carrying on happily) I don't know, so I tend to agree with you regarding 'not much else we can do'. Adding Dave and Juan. Maybe they can tell. Regards, Halil >> + return; >> + } >> + >> + tmp->simm = ais.simm; >> + tmp->nimm = ais.nimm; >> +} >> +