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=-8.3 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,URIBL_BLOCKED,USER_AGENT_SANE_1 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 21121C433DF for ; Fri, 26 Jun 2020 14:17:12 +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 E06A1208C9 for ; Fri, 26 Jun 2020 14:17:11 +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="PFpoANoH" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E06A1208C9 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]:33144 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jopAF-0002vt-7p for qemu-devel@archiver.kernel.org; Fri, 26 Jun 2020 10:17:11 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:46972) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jop9J-00021x-6i for qemu-devel@nongnu.org; Fri, 26 Jun 2020 10:16:13 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:40736 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jop9G-0005J8-BO for qemu-devel@nongnu.org; Fri, 26 Jun 2020 10:16:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593180969; 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: in-reply-to:in-reply-to:references:references; bh=wBO9G9aCaRODxxor/KqzabPijpMlcFAKKWrn9HsbE48=; b=PFpoANoHPTLPrFXdD0aVV1jce9wt2qmrZTZkmf6leJ1g55aa7SXFh5kf8tdJWvt3NdCMfu e5zG+nJWoFbWlXX6r3aD2+sDuvBg97bVX0JjeD/JmVXFxN2iLEAEqjDAI4QW3VZWML60Xq JMxl/7EYGb6YiKZOWFWsnk6yty6vvDA= 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-387-sEgyfmfkOheSlinp4fNYsA-1; Fri, 26 Jun 2020 10:16:07 -0400 X-MC-Unique: sEgyfmfkOheSlinp4fNYsA-1 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 84EE318FE860; Fri, 26 Jun 2020 14:16:04 +0000 (UTC) Received: from work-vm (ovpn-113-27.ams2.redhat.com [10.36.113.27]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 078847F4F1; Fri, 26 Jun 2020 14:15:31 +0000 (UTC) Date: Fri, 26 Jun 2020 15:15:28 +0100 From: "Dr. David Alan Gilbert" To: Alex Williamson Subject: Re: [PATCH QEMU v25 15/17] vfio: Add ioctl to get dirty pages bitmap during dma unmap. Message-ID: <20200626141528.GI3087@work-vm> References: <1592684486-18511-1-git-send-email-kwankhede@nvidia.com> <1592684486-18511-16-git-send-email-kwankhede@nvidia.com> <20200624125614.5e742574@x1.home> <8cf7ffdf-8ba4-d42d-cf8d-4af08686841a@nvidia.com> <20200625131843.1a511078@x1.home> MIME-Version: 1.0 In-Reply-To: <20200625131843.1a511078@x1.home> User-Agent: Mutt/1.14.3 (2020-06-14) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=207.211.31.81; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/26 03:23:21 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, 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_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN 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: cohuck@redhat.com, cjia@nvidia.com, aik@ozlabs.ru, Zhengxiao.zx@alibaba-inc.com, shuangtai.tst@alibaba-inc.com, qemu-devel@nongnu.org, peterx@redhat.com, Kirti Wankhede , 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, 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" * Alex Williamson (alex.williamson@redhat.com) wrote: > On Thu, 25 Jun 2020 20:31:12 +0530 > Kirti Wankhede wrote: > > > On 6/25/2020 12:26 AM, Alex Williamson wrote: > > > On Sun, 21 Jun 2020 01:51:24 +0530 > > > Kirti Wankhede wrote: > > > > > >> With vIOMMU, IO virtual address range can get unmapped while in pre-copy > > >> phase of migration. In that case, unmap ioctl should return pages pinned > > >> in that range and QEMU should find its correcponding guest physical > > >> addresses and report those dirty. > > >> > > >> Suggested-by: Alex Williamson > > >> Signed-off-by: Kirti Wankhede > > >> Reviewed-by: Neo Jia > > >> --- > > >> hw/vfio/common.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++++++++--- > > >> 1 file changed, 81 insertions(+), 4 deletions(-) > > >> > > >> diff --git a/hw/vfio/common.c b/hw/vfio/common.c > > >> index 0518cf228ed5..a06b8f2f66e2 100644 > > >> --- a/hw/vfio/common.c > > >> +++ b/hw/vfio/common.c > > >> @@ -311,11 +311,83 @@ static bool vfio_devices_are_stopped_and_saving(void) > > >> return true; > > >> } > > >> > > >> +static bool vfio_devices_are_running_and_saving(void) > > >> +{ > > >> + VFIOGroup *group; > > >> + VFIODevice *vbasedev; > > >> + > > >> + QLIST_FOREACH(group, &vfio_group_list, next) { > > > > > > Same as previous, I'm curious if we should instead be looking at > > > container granularity. It especially seems to make sense here where > > > we're unmapping from a container, so iterating every device in every > > > group seems excessive. > > > > > > > changing it with container argument. > > > > >> + QLIST_FOREACH(vbasedev, &group->device_list, next) { > > >> + if ((vbasedev->device_state & VFIO_DEVICE_STATE_SAVING) && > > >> + (vbasedev->device_state & VFIO_DEVICE_STATE_RUNNING)) { > > >> + continue; > > >> + } else { > > >> + return false; > > >> + } > > > > > > I'm also not sure about the polarity of this function, should it be if > > > any device is _SAVING we should report the dirty bitmap? For example, > > > what if we have a set of paried failover NICs where we intend to unplug > > > one just prior to stopping the devices, aren't we going to lose dirtied > > > pages with this logic that they all must be running and saving? Thanks, > > > > > > > If migration is initiated, is device unplug allowed? Ideally it > > shouldn't. If it is, then how QEMU handles data stream of device which > > doesn't exist at destination? > > include/hw/qdev-core.h > struct DeviceState { > ... > bool allow_unplug_during_migration; > > AIUI, the failover_pair_id device is likely to be a vfio-pci NIC, > otherwise they'd simply migrate the primary NIC, so there's a very good > chance that a user would configure a VM with a migratable mdev device > and an failover NIC so that they have high speed networking on either > end of the migration. My understanding for that failover code is that happens right at the beginning of migration while we're still in MIGRATION_STATUS_SETUP; whether there's anything that enforces that is a different matter. But, in that case, I don't think you'd be interested in that dirtying. Dave > > _SAVING flag is set during pre-copy and stop-and-copy phase. Here we > > only want to track pages which are unmapped during pre-copy phase, i.e. > > when vCPU are running. In case of VM suspend /saveVM, there is no > > pre-copy phase, but ideally we shouldn't see unmaps when vCPUs are > > stopped, right? But still for safer side, since we know exact phase, I > > would prefer to check for _SAVING and _RUNNING flags. > > We can't have unmaps while vCPUs are stopped, but I think the failover > code allows that we can be in the pre-copy phase where not all devices > support migration. As coded here, it appears that dirty tracking of any > unmap while in that phase is lost. Thanks, > > Alex > > > > >> + } > > >> + } > > >> + return true; > > >> +} > > >> + > > >> +static int vfio_dma_unmap_bitmap(VFIOContainer *container, > > >> + hwaddr iova, ram_addr_t size, > > >> + IOMMUTLBEntry *iotlb) > > >> +{ > > >> + struct vfio_iommu_type1_dma_unmap *unmap; > > >> + struct vfio_bitmap *bitmap; > > >> + uint64_t pages = TARGET_PAGE_ALIGN(size) >> TARGET_PAGE_BITS; > > >> + int ret; > > >> + > > >> + unmap = g_malloc0(sizeof(*unmap) + sizeof(*bitmap)); > > >> + > > >> + unmap->argsz = sizeof(*unmap) + sizeof(*bitmap); > > >> + unmap->iova = iova; > > >> + unmap->size = size; > > >> + unmap->flags |= VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP; > > >> + bitmap = (struct vfio_bitmap *)&unmap->data; > > >> + > > >> + /* > > >> + * cpu_physical_memory_set_dirty_lebitmap() expects pages in bitmap of > > >> + * TARGET_PAGE_SIZE to mark those dirty. Hence set bitmap_pgsize to > > >> + * TARGET_PAGE_SIZE. > > >> + */ > > >> + > > >> + bitmap->pgsize = TARGET_PAGE_SIZE; > > >> + bitmap->size = ROUND_UP(pages, sizeof(__u64) * BITS_PER_BYTE) / > > >> + BITS_PER_BYTE; > > >> + > > >> + if (bitmap->size > container->max_dirty_bitmap_size) { > > >> + error_report("UNMAP: Size of bitmap too big 0x%llx", bitmap->size); > > >> + ret = -E2BIG; > > >> + goto unmap_exit; > > >> + } > > >> + > > >> + bitmap->data = g_try_malloc0(bitmap->size); > > >> + if (!bitmap->data) { > > >> + ret = -ENOMEM; > > >> + goto unmap_exit; > > >> + } > > >> + > > >> + ret = ioctl(container->fd, VFIO_IOMMU_UNMAP_DMA, unmap); > > >> + if (!ret) { > > >> + cpu_physical_memory_set_dirty_lebitmap((uint64_t *)bitmap->data, > > >> + iotlb->translated_addr, pages); > > >> + } else { > > >> + error_report("VFIO_UNMAP_DMA with DIRTY_BITMAP : %m"); > > >> + } > > >> + > > >> + g_free(bitmap->data); > > >> +unmap_exit: > > >> + g_free(unmap); > > >> + return ret; > > >> +} > > >> + > > >> /* > > >> * DMA - Mapping and unmapping for the "type1" IOMMU interface used on x86 > > >> */ > > >> static int vfio_dma_unmap(VFIOContainer *container, > > >> - hwaddr iova, ram_addr_t size) > > >> + hwaddr iova, ram_addr_t size, > > >> + IOMMUTLBEntry *iotlb) > > >> { > > >> struct vfio_iommu_type1_dma_unmap unmap = { > > >> .argsz = sizeof(unmap), > > >> @@ -324,6 +396,11 @@ static int vfio_dma_unmap(VFIOContainer *container, > > >> .size = size, > > >> }; > > >> > > >> + if (iotlb && container->dirty_pages_supported && > > >> + vfio_devices_are_running_and_saving()) { > > >> + return vfio_dma_unmap_bitmap(container, iova, size, iotlb); > > >> + } > > >> + > > >> while (ioctl(container->fd, VFIO_IOMMU_UNMAP_DMA, &unmap)) { > > >> /* > > >> * The type1 backend has an off-by-one bug in the kernel (71a7d3d78e3c > > >> @@ -371,7 +448,7 @@ static int vfio_dma_map(VFIOContainer *container, hwaddr iova, > > >> * the VGA ROM space. > > >> */ > > >> if (ioctl(container->fd, VFIO_IOMMU_MAP_DMA, &map) == 0 || > > >> - (errno == EBUSY && vfio_dma_unmap(container, iova, size) == 0 && > > >> + (errno == EBUSY && vfio_dma_unmap(container, iova, size, NULL) == 0 && > > >> ioctl(container->fd, VFIO_IOMMU_MAP_DMA, &map) == 0)) { > > >> return 0; > > >> } > > >> @@ -542,7 +619,7 @@ static void vfio_iommu_map_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb) > > >> } > > >> } > > >> > > >> - ret = vfio_dma_unmap(container, iova, iotlb->addr_mask + 1); > > >> + ret = vfio_dma_unmap(container, iova, iotlb->addr_mask + 1, iotlb); > > >> if (ret) { > > >> error_report("vfio_dma_unmap(%p, 0x%"HWADDR_PRIx", " > > >> "0x%"HWADDR_PRIx") = %d (%m)", > > >> @@ -853,7 +930,7 @@ static void vfio_listener_region_del(MemoryListener *listener, > > >> } > > >> > > >> if (try_unmap) { > > >> - ret = vfio_dma_unmap(container, iova, int128_get64(llsize)); > > >> + ret = vfio_dma_unmap(container, iova, int128_get64(llsize), NULL); > > >> if (ret) { > > >> error_report("vfio_dma_unmap(%p, 0x%"HWADDR_PRIx", " > > >> "0x%"HWADDR_PRIx") = %d (%m)", > > > > > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK