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bh=VgTQj5k55v4emH60ZREPvOaS3fBrn2fx4lMQO20ls7I=; b=iual+sSRt0kNJPnc73UZN/hKO+tLz1+M9lnqFEL5Eiyzhvw+QPU0vpGeNgfGFcU+9r+oyf +Etv2fluDmOe4P21cFXAufZEvpZVLEhgMVFM1TUtjP/kBzhDy84xoznwGxqeRcPIx/uGKj eCns/TIJAeVL9uxJjCeI4ZWbqUz7QKU= 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-216-0K4zWgeUOpmz_DPGCC81Xg-1; Mon, 19 Oct 2020 16:07:25 -0400 X-MC-Unique: 0K4zWgeUOpmz_DPGCC81Xg-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 4C3AD18B6135; Mon, 19 Oct 2020 20:07:23 +0000 (UTC) Received: from w520.home (ovpn-112-77.phx2.redhat.com [10.3.112.77]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2ACED19D7C; Mon, 19 Oct 2020 20:07:18 +0000 (UTC) Date: Mon, 19 Oct 2020 14:07:17 -0600 From: Alex Williamson To: Kirti Wankhede Subject: Re: [PATCH v26 13/17] vfio: create mapped iova list when vIOMMU is enabled Message-ID: <20201019140717.705368dd@w520.home> In-Reply-To: <52361a71-f812-5f69-be57-93b732e96ed1@nvidia.com> References: <1600817059-26721-1-git-send-email-kwankhede@nvidia.com> <1600817059-26721-14-git-send-email-kwankhede@nvidia.com> <20200925162316.53dbd2b0@x1.home> <20201019112408.470ae1e8@w520.home> <52361a71-f812-5f69-be57-93b732e96ed1@nvidia.com> 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=alex.williamson@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=alex.williamson@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/19 02:32:01 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: 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, 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, 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 Tue, 20 Oct 2020 00:45:28 +0530 Kirti Wankhede wrote: > On 10/19/2020 10:54 PM, Alex Williamson wrote: > > On Mon, 19 Oct 2020 11:31:03 +0530 > > Kirti Wankhede wrote: > > > >> On 9/26/2020 3:53 AM, Alex Williamson wrote: > >>> On Wed, 23 Sep 2020 04:54:15 +0530 > >>> Kirti Wankhede wrote: > >>> > >>>> Create mapped iova list when vIOMMU is enabled. For each mapped iova > >>>> save translated address. Add node to list on MAP and remove node from > >>>> list on UNMAP. > >>>> This list is used to track dirty pages during migration. > >>>> > >>>> Signed-off-by: Kirti Wankhede > >>>> --- > >>>> hw/vfio/common.c | 58 ++++++++++++++++++++++++++++++++++++++----- > >>>> include/hw/vfio/vfio-common.h | 8 ++++++ > >>>> 2 files changed, 60 insertions(+), 6 deletions(-) > >>>> > >>>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c > >>>> index d4959c036dd1..dc56cded2d95 100644 > >>>> --- a/hw/vfio/common.c > >>>> +++ b/hw/vfio/common.c > >>>> @@ -407,8 +407,8 @@ static bool vfio_listener_skipped_section(MemoryRegionSection *section) > >>>> } > >>>> > >>>> /* Called with rcu_read_lock held. */ > >>>> -static bool vfio_get_vaddr(IOMMUTLBEntry *iotlb, void **vaddr, > >>>> - bool *read_only) > >>>> +static bool vfio_get_xlat_addr(IOMMUTLBEntry *iotlb, void **vaddr, > >>>> + ram_addr_t *ram_addr, bool *read_only) > >>>> { > >>>> MemoryRegion *mr; > >>>> hwaddr xlat; > >>>> @@ -439,8 +439,17 @@ static bool vfio_get_vaddr(IOMMUTLBEntry *iotlb, void **vaddr, > >>>> return false; > >>>> } > >>>> > >>>> - *vaddr = memory_region_get_ram_ptr(mr) + xlat; > >>>> - *read_only = !writable || mr->readonly; > >>>> + if (vaddr) { > >>>> + *vaddr = memory_region_get_ram_ptr(mr) + xlat; > >>>> + } > >>>> + > >>>> + if (ram_addr) { > >>>> + *ram_addr = memory_region_get_ram_addr(mr) + xlat; > >>>> + } > >>>> + > >>>> + if (read_only) { > >>>> + *read_only = !writable || mr->readonly; > >>>> + } > >>>> > >>>> return true; > >>>> } > >>>> @@ -450,7 +459,6 @@ static void vfio_iommu_map_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb) > >>>> VFIOGuestIOMMU *giommu = container_of(n, VFIOGuestIOMMU, n); > >>>> VFIOContainer *container = giommu->container; > >>>> hwaddr iova = iotlb->iova + giommu->iommu_offset; > >>>> - bool read_only; > >>>> void *vaddr; > >>>> int ret; > >>>> > >>>> @@ -466,7 +474,10 @@ static void vfio_iommu_map_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb) > >>>> rcu_read_lock(); > >>>> > >>>> if ((iotlb->perm & IOMMU_RW) != IOMMU_NONE) { > >>>> - if (!vfio_get_vaddr(iotlb, &vaddr, &read_only)) { > >>>> + ram_addr_t ram_addr; > >>>> + bool read_only; > >>>> + > >>>> + if (!vfio_get_xlat_addr(iotlb, &vaddr, &ram_addr, &read_only)) { > >>>> goto out; > >>>> } > >>>> /* > >>>> @@ -484,8 +495,28 @@ static void vfio_iommu_map_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb) > >>>> "0x%"HWADDR_PRIx", %p) = %d (%m)", > >>>> container, iova, > >>>> iotlb->addr_mask + 1, vaddr, ret); > >>>> + } else { > >>>> + VFIOIovaRange *iova_range; > >>>> + > >>>> + iova_range = g_malloc0(sizeof(*iova_range)); > >>>> + iova_range->iova = iova; > >>>> + iova_range->size = iotlb->addr_mask + 1; > >>>> + iova_range->ram_addr = ram_addr; > >>>> + > >>>> + QLIST_INSERT_HEAD(&giommu->iova_list, iova_range, next); > >>>> } > >>>> } else { > >>>> + VFIOIovaRange *iova_range, *tmp; > >>>> + > >>>> + QLIST_FOREACH_SAFE(iova_range, &giommu->iova_list, next, tmp) { > >>>> + if (iova_range->iova >= iova && > >>>> + iova_range->iova + iova_range->size <= iova + > >>>> + iotlb->addr_mask + 1) { > >>>> + QLIST_REMOVE(iova_range, next); > >>>> + g_free(iova_range); > >>>> + } > >>>> + } > >>>> + > >>> > >>> > >>> This is some pretty serious overhead... can't we trigger a replay when > >>> migration is enabled to build this information then? > >> > >> Are you suggesting to call memory_region_iommu_replay() before > >> vfio_sync_dirty_bitmap(), which would call vfio_iommu_map_notify() where > >> iova list of mapping is maintained? Then in the notifer check if > >> migration_is_running() and container->dirty_pages_supported == true, > >> then only create iova mapping tree? In this case how would we know that > >> this is triggered by > >> vfio_sync_dirty_bitmap() > >> -> memory_region_iommu_replay() > >> and we don't have to call vfio_dma_map()? > > > > memory_region_iommu_replay() calls a notifier of our choice, so we > > could create a notifier specifically for creating this tree when dirty > > logging is enabled. Thanks, > > > > This would also mean changes in intel_iommu.c such that it would walk > through the iova_tree and call notifier for each entry in iova_tree. I think we already have that in vtd_iommu_replay(), an IOMMUMemoryRegionClass.replay callback is rather a requirement of any vIOMMU intending to support vfio AIUI. > What about other platforms? We will have to handle such cases for > AMD, ARM, PPC etc...? There's already a requirement for a working replay callback to work in any reasonable way with vfio, this is just an additional use case of a callback we already need and use. > I don't see replay callback for AMD, that would result in minimum > IOMMU supported page size granularity walk - which is similar to that > I tried to implement 2-3 versions back. Patch 1/3: https://lists.gnu.org/archive/html/qemu-devel/2020-10/msg00545.html Patch 5/10: https://lists.gnu.org/archive/html/qemu-devel/2020-10/msg02196.html > Does that mean doing such change would improve performance for Intel > IOMMU but worsen for AMD/PPC? We're not adding a new requirement, we already call replay, PPC doesn't use type1. What exactly regresses if we introduce another replay user? > I'm changing list to tree as first level of improvement in this patch. > > Can we do the change you suggested above later as next level of > improvement? AIUI above, we're allocating an object and adding it to a list (soon to be tree) for every vIOMMU mapping, on the off chance that migration might be used, regardless of devices even supporting migration. I can only see that as a runtime performance and size regression. Thanks, Alex