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=-6.8 required=3.0 tests=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 E3715C43613 for ; Fri, 21 Jun 2019 15:22:06 +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 A5F9F206B7 for ; Fri, 21 Jun 2019 15:22:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A5F9F206B7 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]:36062 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1heLMb-00081A-Hk for qemu-devel@archiver.kernel.org; Fri, 21 Jun 2019 11:22:05 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:54512) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1heLHq-0004jK-5d for qemu-devel@nongnu.org; Fri, 21 Jun 2019 11:17:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1heLHo-0008AF-1i for qemu-devel@nongnu.org; Fri, 21 Jun 2019 11:17:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46528) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1heLHn-000894-Of for qemu-devel@nongnu.org; Fri, 21 Jun 2019 11:17:07 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id EE3D730C0DD6; Fri, 21 Jun 2019 15:16:46 +0000 (UTC) Received: from x1.home (ovpn-117-35.phx2.redhat.com [10.3.117.35]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3801B60BFB; Fri, 21 Jun 2019 15:16:39 +0000 (UTC) Date: Fri, 21 Jun 2019 09:16:38 -0600 From: Alex Williamson To: Kirti Wankhede Message-ID: <20190621091638.18127e7a@x1.home> In-Reply-To: <9256515a-f815-58e1-c9ca-81d64bac6db1@nvidia.com> References: <1561041461-22326-1-git-send-email-kwankhede@nvidia.com> <1561041461-22326-9-git-send-email-kwankhede@nvidia.com> <20190620132505.1cf64ac5@x1.home> <9256515a-f815-58e1-c9ca-81d64bac6db1@nvidia.com> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Fri, 21 Jun 2019 15:17:06 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v4 08/13] vfio: Add save state functions to SaveVMHandlers 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: Zhengxiao.zx@Alibaba-inc.com, kevin.tian@intel.com, yi.l.liu@intel.com, cjia@nvidia.com, eskultet@redhat.com, ziye.yang@intel.com, qemu-devel@nongnu.org, cohuck@redhat.com, shuangtai.tst@alibaba-inc.com, dgilbert@redhat.com, zhi.a.wang@intel.com, mlevitsk@redhat.com, pasic@linux.ibm.com, aik@ozlabs.ru, yulei.zhang@intel.com, eauger@redhat.com, felipe@nutanix.com, jonathan.davies@nutanix.com, yan.y.zhao@intel.com, changpeng.liu@intel.com, Ken.Xue@amd.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, 21 Jun 2019 12:08:26 +0530 Kirti Wankhede wrote: > On 6/21/2019 12:55 AM, Alex Williamson wrote: > > On Thu, 20 Jun 2019 20:07:36 +0530 > > Kirti Wankhede wrote: > > > >> Added .save_live_pending, .save_live_iterate and .save_live_complete_precopy > >> functions. These functions handles pre-copy and stop-and-copy phase. > >> > >> In _SAVING|_RUNNING device state or pre-copy phase: > >> - read pending_bytes > >> - read data_offset - indicates kernel driver to write data to staging > >> buffer which is mmapped. > > > > Why is data_offset the trigger rather than data_size? It seems that > > data_offset can't really change dynamically since it might be mmap'd, > > so it seems unnatural to bother re-reading it. > > > > Vendor driver can change data_offset, he can have different data_offset > for device data and dirty pages bitmap. > > >> - read data_size - amount of data in bytes written by vendor driver in migration > >> region. > >> - if data section is trapped, pread() number of bytes in data_size, from > >> data_offset. > >> - if data section is mmaped, read mmaped buffer of size data_size. > >> - Write data packet to file stream as below: > >> {VFIO_MIG_FLAG_DEV_DATA_STATE, data_size, actual data, > >> VFIO_MIG_FLAG_END_OF_STATE } > >> > >> In _SAVING device state or stop-and-copy phase > >> a. read config space of device and save to migration file stream. This > >> doesn't need to be from vendor driver. Any other special config state > >> from driver can be saved as data in following iteration. > >> b. read pending_bytes - indicates kernel driver to write data to staging > >> buffer which is mmapped. > > > > Is it pending_bytes or data_offset that triggers the write out of > > data? Why pending_bytes vs data_size? I was interpreting > > pending_bytes as the total data size while data_size is the size > > available to read now, so assumed data_size would be more closely > > aligned to making the data available. > > > > Sorry, that's my mistake while editing, its read data_offset as in above > case. > > >> c. read data_size - amount of data in bytes written by vendor driver in > >> migration region. > >> d. if data section is trapped, pread() from data_offset of size data_size. > >> e. if data section is mmaped, read mmaped buffer of size data_size. > > > > Should this read as "pread() from data_offset of data_size, or > > optionally if mmap is supported on the data area, read data_size from > > start of mapped buffer"? IOW, pread should always work. Same in > > previous section. > > > > ok. I'll update. > > >> f. Write data packet as below: > >> {VFIO_MIG_FLAG_DEV_DATA_STATE, data_size, actual data} > >> g. iterate through steps b to f until (pending_bytes > 0) > > > > s/until/while/ > > Ok. > > > > >> h. Write {VFIO_MIG_FLAG_END_OF_STATE} > >> > >> .save_live_iterate runs outside the iothread lock in the migration case, which > >> could race with asynchronous call to get dirty page list causing data corruption > >> in mapped migration region. Mutex added here to serial migration buffer read > >> operation. > > > > Would we be ahead to use different offsets within the region for device > > data vs dirty bitmap to avoid this? > > > > Lock will still be required to serialize the read/write operations on > vfio_device_migration_info structure in the region. > > > >> Signed-off-by: Kirti Wankhede > >> Reviewed-by: Neo Jia > >> --- > >> hw/vfio/migration.c | 212 ++++++++++++++++++++++++++++++++++++++++++++++++++++ > >> 1 file changed, 212 insertions(+) > >> > >> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c > >> index fe0887c27664..0a2f30872316 100644 > >> --- a/hw/vfio/migration.c > >> +++ b/hw/vfio/migration.c > >> @@ -107,6 +107,111 @@ static int vfio_migration_set_state(VFIODevice *vbasedev, uint32_t state) > >> return 0; > >> } > >> > >> +static int vfio_save_buffer(QEMUFile *f, VFIODevice *vbasedev) > >> +{ > >> + VFIOMigration *migration = vbasedev->migration; > >> + VFIORegion *region = &migration->region.buffer; > >> + uint64_t data_offset = 0, data_size = 0; > >> + int ret; > >> + > >> + ret = pread(vbasedev->fd, &data_offset, sizeof(data_offset), > >> + region->fd_offset + offsetof(struct vfio_device_migration_info, > >> + data_offset)); > >> + if (ret != sizeof(data_offset)) { > >> + error_report("Failed to get migration buffer data offset %d", > >> + ret); > >> + return -EINVAL; > >> + } > >> + > >> + ret = pread(vbasedev->fd, &data_size, sizeof(data_size), > >> + region->fd_offset + offsetof(struct vfio_device_migration_info, > >> + data_size)); > >> + if (ret != sizeof(data_size)) { > >> + error_report("Failed to get migration buffer data size %d", > >> + ret); > >> + return -EINVAL; > >> + } > >> + > >> + if (data_size > 0) { > >> + void *buf = NULL; > >> + bool buffer_mmaped = false; > >> + > >> + if (region->mmaps) { > >> + int i; > >> + > >> + for (i = 0; i < region->nr_mmaps; i++) { > >> + if ((data_offset >= region->mmaps[i].offset) && > >> + (data_offset < region->mmaps[i].offset + > >> + region->mmaps[i].size)) { > >> + buf = region->mmaps[i].mmap + (data_offset - > >> + region->mmaps[i].offset); > > > > So you're expecting that data_offset is somewhere within the data > > area. Why doesn't the data always simply start at the beginning of the > > data area? ie. data_offset would coincide with the beginning of the > > mmap'able area (if supported) and be static. Does this enable some > > functionality in the vendor driver? > > Do you want to enforce that to vendor driver? > From the feedback on previous version I thought vendor driver should > define data_offset within the region > "I'd suggest that the vendor driver expose a read-only > data_offset that matches a sparse mmap capability entry should the > driver support mmap. The use should always read or write data from the > vendor defined data_offset" > > This also adds flexibility to vendor driver such that vendor driver can > define different data_offset for device data and dirty page bitmap > within same mmaped region. I agree, it adds flexibility, the protocol was not evident to me until I got here though. > > Does resume data need to be > > written from the same offset where it's read? > > No, resume data should be written from the data_offset that vendor > driver provided during resume. s/resume/save/? Or is this saying that on resume that the vendor driver is requesting a specific block of data via data_offset? I think resume is going to be directed by the user, writing in the same order they received the data. Thanks, Alex > >> + buffer_mmaped = true; > >> + break; > >> + } > >> + } > >> + } > >> + > >> + if (!buffer_mmaped) { > >> + buf = g_malloc0(data_size); > >> + ret = pread(vbasedev->fd, buf, data_size, > >> + region->fd_offset + data_offset); > >> + if (ret != data_size) { > >> + error_report("Failed to get migration data %d", ret); > >> + g_free(buf); > >> + return -EINVAL; > >> + } > >> + } > >> + > >> + qemu_put_be64(f, data_size); > >> + qemu_put_buffer(f, buf, data_size); > >> + > >> + if (!buffer_mmaped) { > >> + g_free(buf); > >> + } > >> + migration->pending_bytes -= data_size; > >> + } else { > >> + qemu_put_be64(f, data_size); > >> + } > >> + > >> + ret = qemu_file_get_error(f); > >> + > >> + return data_size; > >> +} > >> + > >> +static int vfio_update_pending(VFIODevice *vbasedev) > >> +{ > >> + VFIOMigration *migration = vbasedev->migration; > >> + VFIORegion *region = &migration->region.buffer; > >> + uint64_t pending_bytes = 0; > >> + int ret; > >> + > >> + ret = pread(vbasedev->fd, &pending_bytes, sizeof(pending_bytes), > >> + region->fd_offset + offsetof(struct vfio_device_migration_info, > >> + pending_bytes)); > > > > Did this trigger the vendor driver to write out to the data area when > > we don't need it to? > > > > No, as I mentioned above, I'll update the description. > > Thanks, > Kirti > > >> + if ((ret < 0) || (ret != sizeof(pending_bytes))) { > >> + error_report("Failed to get pending bytes %d", ret); > >> + migration->pending_bytes = 0; > >> + return (ret < 0) ? ret : -EINVAL; > >> + } > >> + > >> + migration->pending_bytes = pending_bytes; > >> + return 0; > >> +} > >> + > >> +static int vfio_save_device_config_state(QEMUFile *f, void *opaque) > >> +{ > >> + VFIODevice *vbasedev = opaque; > >> + > >> + qemu_put_be64(f, VFIO_MIG_FLAG_DEV_CONFIG_STATE); > >> + > >> + if (vbasedev->type == VFIO_DEVICE_TYPE_PCI) { > >> + vfio_pci_save_config(vbasedev, f); > >> + } > >> + qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE); > >> + > >> + return qemu_file_get_error(f); > >> +} > >> + > >> /* ---------------------------------------------------------------------- */ > >> > >> static int vfio_save_setup(QEMUFile *f, void *opaque) > >> @@ -163,9 +268,116 @@ static void vfio_save_cleanup(void *opaque) > >> } > >> } > >> > >> +static void vfio_save_pending(QEMUFile *f, void *opaque, > >> + uint64_t threshold_size, > >> + uint64_t *res_precopy_only, > >> + uint64_t *res_compatible, > >> + uint64_t *res_postcopy_only) > >> +{ > >> + VFIODevice *vbasedev = opaque; > >> + VFIOMigration *migration = vbasedev->migration; > >> + int ret; > >> + > >> + ret = vfio_update_pending(vbasedev); > >> + if (ret) { > >> + return; > >> + } > >> + > >> + if (vbasedev->device_state & VFIO_DEVICE_STATE_RUNNING) { > >> + *res_precopy_only += migration->pending_bytes; > >> + } else { > >> + *res_postcopy_only += migration->pending_bytes; > >> + } > >> + *res_compatible += 0; > >> +} > >> + > >> +static int vfio_save_iterate(QEMUFile *f, void *opaque) > >> +{ > >> + VFIODevice *vbasedev = opaque; > >> + VFIOMigration *migration = vbasedev->migration; > >> + int ret; > >> + > >> + qemu_put_be64(f, VFIO_MIG_FLAG_DEV_DATA_STATE); > >> + > >> + qemu_mutex_lock(&migration->lock); > >> + ret = vfio_save_buffer(f, vbasedev); > >> + qemu_mutex_unlock(&migration->lock); > >> + > >> + if (ret < 0) { > >> + error_report("vfio_save_buffer failed %s", > >> + strerror(errno)); > >> + return ret; > >> + } > >> + > >> + qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE); > >> + > >> + ret = qemu_file_get_error(f); > >> + if (ret) { > >> + return ret; > >> + } > >> + > >> + return ret; > >> +} > >> + > >> +static int vfio_save_complete_precopy(QEMUFile *f, void *opaque) > >> +{ > >> + VFIODevice *vbasedev = opaque; > >> + VFIOMigration *migration = vbasedev->migration; > >> + int ret; > >> + > >> + ret = vfio_migration_set_state(vbasedev, VFIO_DEVICE_STATE_SAVING); > >> + if (ret) { > >> + error_report("Failed to set state STOP and SAVING"); > >> + return ret; > >> + } > >> + > >> + ret = vfio_save_device_config_state(f, opaque); > >> + if (ret) { > >> + return ret; > >> + } > >> + > >> + ret = vfio_update_pending(vbasedev); > >> + if (ret) { > >> + return ret; > >> + } > >> + > >> + while (migration->pending_bytes > 0) { > >> + qemu_put_be64(f, VFIO_MIG_FLAG_DEV_DATA_STATE); > >> + ret = vfio_save_buffer(f, vbasedev); > >> + if (ret < 0) { > >> + error_report("Failed to save buffer"); > >> + return ret; > >> + } else if (ret == 0) { > >> + break; > >> + } > >> + > >> + ret = vfio_update_pending(vbasedev); > >> + if (ret) { > >> + return ret; > >> + } > >> + } > >> + > >> + qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE); > >> + > >> + ret = qemu_file_get_error(f); > >> + if (ret) { > >> + return ret; > >> + } > >> + > >> + ret = vfio_migration_set_state(vbasedev, VFIO_DEVICE_STATE_STOPPED); > >> + if (ret) { > >> + error_report("Failed to set state STOPPED"); > >> + return ret; > >> + } > >> + return ret; > >> +} > >> + > >> static SaveVMHandlers savevm_vfio_handlers = { > >> .save_setup = vfio_save_setup, > >> .save_cleanup = vfio_save_cleanup, > >> + .save_live_pending = vfio_save_pending, > >> + .save_live_iterate = vfio_save_iterate, > >> + .save_live_complete_precopy = vfio_save_complete_precopy, > >> }; > >> > >> /* ---------------------------------------------------------------------- */ > >