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=-9.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 05F1AC4363A for ; Tue, 20 Oct 2020 16:39:57 +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 5089322242 for ; Tue, 20 Oct 2020 16:39:56 +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="KoImGANc" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5089322242 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]:43106 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kUufz-000160-84 for qemu-devel@archiver.kernel.org; Tue, 20 Oct 2020 12:39:55 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:45176) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kUuSb-0002e1-0U for qemu-devel@nongnu.org; Tue, 20 Oct 2020 12:26:05 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:42107) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kUuSV-0007bs-MO for qemu-devel@nongnu.org; Tue, 20 Oct 2020 12:26:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1603211153; 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=DrwutcZjdleYUH/m4Q/XzbDqHVGY42CIZ3t5X3tvPoE=; b=KoImGANckGgq0iz3c8jwe2V1IMXMasqIg1Lbj1iGol5RNsUtUn9Vjut4JRZIaSWPsw31a/ TWzQo3bQDeHMFzM/MtNyESNJzj2bMc9YQGEcQxU5NHMh9bbJsT5h2PrXCvn4Z+/CNouAPS b9jamKdWQsm8vS3zxw6+T512XmaND4I= 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-584-CKYHyv7tO1ylex36dlCJoQ-1; Tue, 20 Oct 2020 12:25:49 -0400 X-MC-Unique: CKYHyv7tO1ylex36dlCJoQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 63E461084C87; Tue, 20 Oct 2020 16:25:47 +0000 (UTC) Received: from gondolin (ovpn-114-95.ams2.redhat.com [10.36.114.95]) by smtp.corp.redhat.com (Postfix) with ESMTP id C7E2527CC8; Tue, 20 Oct 2020 16:25:35 +0000 (UTC) Date: Tue, 20 Oct 2020 18:25:32 +0200 From: Cornelia Huck To: Kirti Wankhede Subject: Re: [PATCH v26 09/17] vfio: Add load state functions to SaveVMHandlers Message-ID: <20201020182532.76b544b6.cohuck@redhat.com> In-Reply-To: <5ca09cd6-efd6-ed8d-277f-5a1b42b5835c@nvidia.com> References: <1600817059-26721-1-git-send-email-kwankhede@nvidia.com> <1600817059-26721-10-git-send-email-kwankhede@nvidia.com> <20201001120730.36eb76dd.cohuck@redhat.com> <5ca09cd6-efd6-ed8d-277f-5a1b42b5835c@nvidia.com> Organization: Red Hat GmbH MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=cohuck@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=cohuck@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/20 01:15:43 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: cjia@nvidia.com, aik@ozlabs.ru, Zhengxiao.zx@Alibaba-inc.com, shuangtai.tst@alibaba-inc.com, qemu-devel@nongnu.org, peterx@redhat.com, eauger@redhat.com, yi.l.liu@intel.com, quintela@redhat.com, ziye.yang@intel.com, armbru@redhat.com, mlevitsk@redhat.com, pasic@linux.ibm.com, felipe@nutanix.com, zhi.a.wang@intel.com, kevin.tian@intel.com, yan.y.zhao@intel.com, dgilbert@redhat.com, alex.williamson@redhat.com, changpeng.liu@intel.com, eskultet@redhat.com, Ken.Xue@amd.com, jonathan.davies@nutanix.com, pbonzini@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, 19 Oct 2020 02:17:43 +0530 Kirti Wankhede wrote: > On 10/1/2020 3:37 PM, Cornelia Huck wrote: > > On Wed, 23 Sep 2020 04:54:11 +0530 > > Kirti Wankhede wrote: > > > >> Sequence during _RESUMING device state: > >> While data for this device is available, repeat below steps: > >> a. read data_offset from where user application should write data. > >> b. write data of data_size to migration region from data_offset. > >> c. write data_size which indicates vendor driver that data is written in > >> staging buffer. > >> > >> For user, data is opaque. User should write data in the same order as > >> received. > >> > >> Signed-off-by: Kirti Wankhede > >> Reviewed-by: Neo Jia > >> Reviewed-by: Dr. David Alan Gilbert > >> --- > >> hw/vfio/migration.c | 170 +++++++++++++++++++++++++++++++++++++++++++++++++++ > >> hw/vfio/trace-events | 3 + > >> 2 files changed, 173 insertions(+) > >> > >> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c > >> index 4611bb972228..ffd70282dd0e 100644 > >> --- a/hw/vfio/migration.c > >> +++ b/hw/vfio/migration.c > >> @@ -328,6 +328,33 @@ static int vfio_save_device_config_state(QEMUFile *f, void *opaque) > >> return qemu_file_get_error(f); > >> } > >> > >> +static int vfio_load_device_config_state(QEMUFile *f, void *opaque) > >> +{ > >> + VFIODevice *vbasedev = opaque; > >> + uint64_t data; > >> + > >> + if (vbasedev->ops && vbasedev->ops->vfio_load_config) { > >> + int ret; > >> + > >> + ret = vbasedev->ops->vfio_load_config(vbasedev, f); > >> + if (ret) { > >> + error_report("%s: Failed to load device config space", > >> + vbasedev->name); > >> + return ret; > >> + } > >> + } > >> + > >> + data = qemu_get_be64(f); > >> + if (data != VFIO_MIG_FLAG_END_OF_STATE) { > >> + error_report("%s: Failed loading device config space, " > >> + "end flag incorrect 0x%"PRIx64, vbasedev->name, data); > > > > I'm confused here: If we don't have a vfio_load_config callback, or if > > that callback did not read everything, we also might end up with a > > value that's not END_OF_STATE... in that case, the problem is not with > > the stream, but rather with the consumer? > > Right, hence "end flag incorrect" is reported. Yes, but that's what I find confusing... a missing or incorrect vfio_load_config callback does not have anything to do with incorrect end flags as present in the stream, but with the consumer not reading things correctly. If I got this error, I would go looking whether there's anything wrong with the stream and the code that produced it, and that's the wrong direction. (...) > >> +static int vfio_load_state(QEMUFile *f, void *opaque, int version_id) > >> +{ > >> + VFIODevice *vbasedev = opaque; > >> + VFIOMigration *migration = vbasedev->migration; > >> + int ret = 0; > >> + uint64_t data, data_size; > >> + > >> + data = qemu_get_be64(f); > >> + while (data != VFIO_MIG_FLAG_END_OF_STATE) { > >> + > >> + trace_vfio_load_state(vbasedev->name, data); > >> + > >> + switch (data) { > >> + case VFIO_MIG_FLAG_DEV_CONFIG_STATE: > >> + { > >> + ret = vfio_load_device_config_state(f, opaque); > >> + if (ret) { > >> + return ret; > >> + } > >> + break; > >> + } > >> + case VFIO_MIG_FLAG_DEV_SETUP_STATE: > >> + { > >> + data = qemu_get_be64(f); > >> + if (data == VFIO_MIG_FLAG_END_OF_STATE) { > >> + return ret; > >> + } else { > >> + error_report("%s: SETUP STATE: EOS not found 0x%"PRIx64, > >> + vbasedev->name, data); > >> + return -EINVAL; > >> + } > >> + break; > >> + } > >> + case VFIO_MIG_FLAG_DEV_DATA_STATE: > >> + { > >> + VFIORegion *region = &migration->region; > >> + uint64_t data_offset = 0, size; > > > > I think this function would benefit from splitting this off into a > > function handling DEV_DATA_STATE. It is quite hard to follow through > > all the checks and find out when we continue, and when we break off. > > > > Each switch case has a break, we break off on success cases, where as we > return error if we encounter any case where (ret < 0) Of course, but I don't find it easy to follow when the errors are happening. > > > > Some documentation about the markers would also be really helpful. > > Sure adding it in patch 07, where these are defined. > > > The logic seems to be: > > - DEV_CONFIG_STATE has config data and must be ended by END_OF_STATE > Right > > > - DEV_SETUP_STATE has only END_OF_STATE, no data > Right now there is no data, but this is provision to add data if > required in future. > > > - DEV_DATA_STATE has... data; if there's any END_OF_STATE, it's buried > > far down in the called functions > > > > This is not correct, END_OF_STATE is after data. Moved data buffer > loading logic to function vfio_load_buffer(), so DEV_DATA_STATE looks > simplified as below. Hope this helps. > > case VFIO_MIG_FLAG_DEV_DATA_STATE: > { > uint64_t data_size; > > data_size = qemu_get_be64(f); > if (data_size == 0) { > break; > } > > ret = vfio_load_buffer(f, vbasedev, data_size); > if (ret < 0) { > return ret; > } > break; > } Hm. What I find not that easy to follow is the structure here: while (!end_marker) { switch (data) { case config_state: if (load_config) return error; break; case setup_state: read_next_value(); if (end_marker) return 0; else return error; break; case data_state: size = read_next_value(); if (!size) break; if (vfio_load_buffer()) return error; break; default: return error; } read_next_value(); if (qemu_file_get_error()) return error; } So, what I don't understand is: - Why do we call qemu_file_get_error() only after we went through the whole switch? This means it is never called for the setup_state/end_marker pair. - If we look for an end marker for config_state and data_state, it's buried in the called functions. How can we be sure they actually do look for it? That needs at least a comment. - If we find a valid setup_state section, we return success immediately. If we find valid config_state or data_state sections, we keep looking for more sections. Why? This also needs at least a comment. > > Also handling the case if data_size is greater than the data section of > migration region at destination in vfio_load_buffer()in my next version. > > Thanks, > Kirti > > > > >> + > >> + data_size = size = qemu_get_be64(f); > >> + if (data_size == 0) { > >> + break; > >> + } > >> + > >> + ret = vfio_mig_read(vbasedev, &data_offset, sizeof(data_offset), > >> + region->fd_offset + > >> + offsetof(struct vfio_device_migration_info, > >> + data_offset)); > >> + if (ret < 0) { > >> + return ret; > >> + } > >> + > >> + trace_vfio_load_state_device_data(vbasedev->name, data_offset, > >> + data_size); > >> + > >> + while (size) { > >> + void *buf = NULL; > >> + uint64_t sec_size; > >> + bool buf_alloc = false; > >> + > >> + buf = get_data_section_size(region, data_offset, size, > >> + &sec_size); > >> + > >> + if (!buf) { > >> + buf = g_try_malloc(sec_size); > >> + if (!buf) { > >> + error_report("%s: Error allocating buffer ", __func__); > >> + return -ENOMEM; > >> + } > >> + buf_alloc = true; > >> + } > >> + > >> + qemu_get_buffer(f, buf, sec_size); > >> + > >> + if (buf_alloc) { > >> + ret = vfio_mig_write(vbasedev, buf, sec_size, > >> + region->fd_offset + data_offset); > >> + g_free(buf); > >> + > >> + if (ret < 0) { > >> + return ret; > >> + } > >> + } > >> + size -= sec_size; > >> + data_offset += sec_size; > >> + } > >> + > >> + ret = vfio_mig_write(vbasedev, &data_size, sizeof(data_size), > >> + region->fd_offset + > >> + offsetof(struct vfio_device_migration_info, data_size)); > >> + if (ret < 0) { > >> + return ret; > >> + } > >> + break; > >> + } > >> + > >> + default: > >> + error_report("%s: Unknown tag 0x%"PRIx64, vbasedev->name, data); > >> + return -EINVAL; > >> + } > >> + > >> + data = qemu_get_be64(f); > >> + ret = qemu_file_get_error(f); > >> + if (ret) { > >> + return ret; > >> + } > >> + } > >> + > >> + return ret; > >> +} > >> +