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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 75D3AC4361B for ; Thu, 17 Dec 2020 18:37:47 +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 D851D238EC for ; Thu, 17 Dec 2020 18:37:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D851D238EC 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]:53880 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kpy9p-0003wA-V8 for qemu-devel@archiver.kernel.org; Thu, 17 Dec 2020 13:37:45 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:58998) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kpy8l-0003Oz-Jo for qemu-devel@nongnu.org; Thu, 17 Dec 2020 13:36:39 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:30708) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kpy8i-0000mx-KH for qemu-devel@nongnu.org; Thu, 17 Dec 2020 13:36:39 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1608230195; 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=+oNQHB6RHjaJOHNrFItG1+74R11qnMpKktaVKmFJlqg=; b=fNhwHOWKgkP8qbNGwZKyasgk4Zi52j2ksGclqGcOp4n1o0Sg9vOFoAtIfS+3Fpj5rhzRBI Ft2wJkZy3ufLSS0ADdEJLSuVtKckc9+7K+u57SEyJ1fJ+DZ8FRecSo0LuH8tqqot83dJha SdG6+ifqdL4saa1H/tH3voRNeLVTbgA= 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-435--dSEPiTrMGiAfx9Fbt7QBQ-1; Thu, 17 Dec 2020 13:36:33 -0500 X-MC-Unique: -dSEPiTrMGiAfx9Fbt7QBQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C4AAB81A2BD; Thu, 17 Dec 2020 18:36:14 +0000 (UTC) Received: from omen.home (ovpn-112-193.phx2.redhat.com [10.3.112.193]) by smtp.corp.redhat.com (Postfix) with ESMTP id 44AE460CE9; Thu, 17 Dec 2020 18:36:13 +0000 (UTC) Date: Thu, 17 Dec 2020 11:36:12 -0700 From: Alex Williamson To: David Hildenbrand Subject: Re: [PATCH v3 05/10] vfio: Support for RamDiscardMgr in the !vIOMMU case Message-ID: <20201217113612.0410b143@omen.home> In-Reply-To: <20201216141200.118742-6-david@redhat.com> References: <20201216141200.118742-1-david@redhat.com> <20201216141200.118742-6-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 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=216.205.24.124; envelope-from=alex.williamson@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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_H3=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: Pankaj Gupta , Wei Yang , "Michael S. Tsirkin" , Jonathan Cameron , qemu-devel@nongnu.org, Peter Xu , "Dr . David Alan Gilbert" , Auger Eric , teawater , Igor Mammedov , Paolo Bonzini , Marek Kedzierski Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, 16 Dec 2020 15:11:55 +0100 David Hildenbrand wrote: > Implement support for RamDiscardMgr, to prepare for virtio-mem > support. Instead of mapping the whole memory section, we only map > "populated" parts and update the mapping when notified about > discarding/population of memory via the RamDiscardListener. Similarly, when > syncing the dirty bitmaps, sync only the actually mapped (populated) parts > by replaying via the notifier. > > Small mapping granularity is problematic for vfio, because we might run out > of mappings. Indicate virito-mem as one of the problematic parts when > warning in vfio_container_dma_reserve() to at least make users aware that > there is such a limitation. > > Using virtio-mem with vfio is still blocked via > ram_block_discard_disable()/ram_block_discard_require() after this patch. > > Cc: Paolo Bonzini > Cc: "Michael S. Tsirkin" > Cc: Alex Williamson > Cc: Dr. David Alan Gilbert > Cc: Igor Mammedov > Cc: Pankaj Gupta > Cc: Peter Xu > Cc: Auger Eric > Cc: Wei Yang > Cc: teawater > Cc: Marek Kedzierski > Signed-off-by: David Hildenbrand > --- > hw/vfio/common.c | 213 +++++++++++++++++++++++++++++++++- > include/hw/vfio/vfio-common.h | 13 +++ > 2 files changed, 225 insertions(+), 1 deletion(-) > > diff --git a/hw/vfio/common.c b/hw/vfio/common.c > index 5ad88d476f..b1582be1e8 100644 > --- a/hw/vfio/common.c > +++ b/hw/vfio/common.c > @@ -296,7 +296,8 @@ static void vfio_container_dma_reserve(VFIOContainer *container, > container->dma_reserved += dma_mappings; > if (!warned && container->dma_max && > container->dma_reserved > container->dma_max) { > - warn_report("%s: possibly running out of DMA mappings. " > + warn_report("%s: possibly running out of DMA mappings. E.g., try" > + " increasing the 'block-size' of virtio-mem devies." > " Maximum number of DMA mappings: %d", __func__, > container->dma_max); > } > @@ -674,6 +675,146 @@ out: > rcu_read_unlock(); > } > > +static void vfio_ram_discard_notify_discard(RamDiscardListener *rdl, > + const MemoryRegion *mr, > + ram_addr_t offset, ram_addr_t size) > +{ > + VFIORamDiscardListener *vrdl = container_of(rdl, VFIORamDiscardListener, > + listener); > + const hwaddr mr_start = MAX(offset, vrdl->offset_within_region); > + const hwaddr mr_end = MIN(offset + size, > + vrdl->offset_within_region + vrdl->size); > + const hwaddr iova = mr_start - vrdl->offset_within_region + > + vrdl->offset_within_address_space; > + int ret; > + > + if (mr_start >= mr_end) { > + return; > + } > + > + /* Unmap with a single call. */ > + ret = vfio_dma_unmap(vrdl->container, iova, mr_end - mr_start, NULL); > + if (ret) { > + error_report("%s: vfio_dma_unmap() failed: %s", __func__, > + strerror(-ret)); > + } > +} > + > +static int vfio_ram_discard_notify_populate(RamDiscardListener *rdl, > + const MemoryRegion *mr, > + ram_addr_t offset, ram_addr_t size) > +{ > + VFIORamDiscardListener *vrdl = container_of(rdl, VFIORamDiscardListener, > + listener); > + const hwaddr mr_end = MIN(offset + size, > + vrdl->offset_within_region + vrdl->size); > + hwaddr mr_start = MAX(offset, vrdl->offset_within_region); > + hwaddr mr_next, iova; > + void *vaddr; > + int ret; > + > + /* > + * Map in (aligned within memory region) minimum granularity, so we can > + * unmap in minimum granularity later. > + */ > + for (; mr_start < mr_end; mr_start = mr_next) { > + mr_next = QEMU_ALIGN_UP(mr_start + 1, vrdl->granularity); > + mr_next = MIN(mr_next, mr_end); > + > + iova = mr_start - vrdl->offset_within_region + > + vrdl->offset_within_address_space; > + vaddr = memory_region_get_ram_ptr(vrdl->mr) + mr_start; > + > + ret = vfio_dma_map(vrdl->container, iova, mr_next - mr_start, > + vaddr, mr->readonly); > + if (ret) { > + /* Rollback */ > + vfio_ram_discard_notify_discard(rdl, mr, offset, size); > + return ret; > + } > + } > + return 0; > +} > + > +static void vfio_ram_discard_notify_discard_all(RamDiscardListener *rdl, > + const MemoryRegion *mr) > +{ > + VFIORamDiscardListener *vrdl = container_of(rdl, VFIORamDiscardListener, > + listener); > + int ret; > + > + /* Unmap with a single call. */ > + ret = vfio_dma_unmap(vrdl->container, vrdl->offset_within_address_space, > + vrdl->size, NULL); > + if (ret) { > + error_report("%s: vfio_dma_unmap() failed: %s", __func__, > + strerror(-ret)); > + } > +} > + > +static void vfio_register_ram_discard_notifier(VFIOContainer *container, > + MemoryRegionSection *section) > +{ > + RamDiscardMgr *rdm = memory_region_get_ram_discard_mgr(section->mr); > + RamDiscardMgrClass *rdmc = RAM_DISCARD_MGR_GET_CLASS(rdm); > + VFIORamDiscardListener *vrdl; > + > + vrdl = g_new0(VFIORamDiscardListener, 1); > + vrdl->container = container; > + vrdl->mr = section->mr; > + vrdl->offset_within_region = section->offset_within_region; > + vrdl->offset_within_address_space = section->offset_within_address_space; > + vrdl->size = int128_get64(section->size); > + vrdl->granularity = rdmc->get_min_granularity(rdm, section->mr); > + vrdl->dma_max = vrdl->size / vrdl->granularity; > + if (!QEMU_IS_ALIGNED(vrdl->size, vrdl->granularity) || > + !QEMU_IS_ALIGNED(vrdl->offset_within_region, vrdl->granularity)) { > + vrdl->dma_max++; > + } > + > + /* Ignore some corner cases not relevant in practice. */ > + g_assert(QEMU_IS_ALIGNED(vrdl->offset_within_region, TARGET_PAGE_SIZE)); > + g_assert(QEMU_IS_ALIGNED(vrdl->offset_within_address_space, > + TARGET_PAGE_SIZE)); > + g_assert(QEMU_IS_ALIGNED(vrdl->size, TARGET_PAGE_SIZE)); > + > + /* We could consume quite some mappings later. */ > + vfio_container_dma_reserve(container, vrdl->dma_max); Aha, I guess this is where the "reservation" aspect begins to appear. Should this be its own counter though, perhaps dma_discard_max_mappings? The populate and discard callbacks could further divide this into used and outstanding counters. However, TBH I'm not sure I understand the counters since this is probably the most robust mapping path where we can actually safely nak a populate callback. Maybe rather than any of these runtime counters we should just walk the vrdl_list, calculate max mappings, and if that exceeds some large fraction of available mappings, issue a warning (not that they wouldn't be useful for tracing). Thanks, Alex > + > + ram_discard_listener_init(&vrdl->listener, > + vfio_ram_discard_notify_populate, > + vfio_ram_discard_notify_discard, > + vfio_ram_discard_notify_discard_all); > + rdmc->register_listener(rdm, section->mr, &vrdl->listener); > + QLIST_INSERT_HEAD(&container->vrdl_list, vrdl, next); > +} > + > +static void vfio_unregister_ram_discard_listener(VFIOContainer *container, > + MemoryRegionSection *section) > +{ > + RamDiscardMgr *rdm = memory_region_get_ram_discard_mgr(section->mr); > + RamDiscardMgrClass *rdmc = RAM_DISCARD_MGR_GET_CLASS(rdm); > + VFIORamDiscardListener *vrdl = NULL; > + > + QLIST_FOREACH(vrdl, &container->vrdl_list, next) { > + if (vrdl->mr == section->mr && > + vrdl->offset_within_region == section->offset_within_region) { > + break; > + } > + } > + > + if (!vrdl) { > + hw_error("vfio: Trying to unregister missing RAM discard listener"); > + } > + > + rdmc->unregister_listener(rdm, section->mr, &vrdl->listener); > + QLIST_REMOVE(vrdl, next); > + > + vfio_container_dma_unreserve(container, vrdl->dma_max); > + > + g_free(vrdl); > +} > + > static void vfio_listener_region_add(MemoryListener *listener, > MemoryRegionSection *section) > { > @@ -834,6 +975,16 @@ static void vfio_listener_region_add(MemoryListener *listener, > > /* Here we assume that memory_region_is_ram(section->mr)==true */ > > + /* > + * For RAM memory regions with a RamDiscardMgr, we only want to > + * register the actually "used" parts - and update the mapping whenever > + * we're notified about changes. > + */ > + if (memory_region_has_ram_discard_mgr(section->mr)) { > + vfio_register_ram_discard_notifier(container, section); > + return; > + } > + > vaddr = memory_region_get_ram_ptr(section->mr) + > section->offset_within_region + > (iova - section->offset_within_address_space); > @@ -975,6 +1126,10 @@ static void vfio_listener_region_del(MemoryListener *listener, > > pgmask = (1ULL << ctz64(hostwin->iova_pgsizes)) - 1; > try_unmap = !((iova & pgmask) || (int128_get64(llsize) & pgmask)); > + } else if (memory_region_has_ram_discard_mgr(section->mr)) { > + vfio_unregister_ram_discard_listener(container, section); > + /* Unregistering will trigger an unmap. */ > + try_unmap = false; > } > > if (try_unmap) { > @@ -1107,6 +1262,59 @@ static void vfio_iommu_map_dirty_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb) > rcu_read_unlock(); > } > > +static int vfio_ram_discard_notify_dirty_bitmap(RamDiscardListener *rdl, > + const MemoryRegion *mr, > + ram_addr_t offset, > + ram_addr_t size) > +{ > + VFIORamDiscardListener *vrdl = container_of(rdl, VFIORamDiscardListener, > + listener); > + const hwaddr mr_start = MAX(offset, vrdl->offset_within_region); > + const hwaddr mr_end = MIN(offset + size, > + vrdl->offset_within_region + vrdl->size); > + const hwaddr iova = mr_start - vrdl->offset_within_region + > + vrdl->offset_within_address_space; > + ram_addr_t ram_addr; > + int ret; > + > + if (mr_start >= mr_end) { > + return 0; > + } > + > + /* > + * Sync the whole mapped region (spanning multiple individual mappings) > + * in one go. > + */ > + ram_addr = memory_region_get_ram_addr(vrdl->mr) + mr_start; > + ret = vfio_get_dirty_bitmap(vrdl->container, iova, mr_end - mr_start, > + ram_addr); > + return ret; > +} > + > +static int vfio_sync_ram_discard_listener_dirty_bitmap(VFIOContainer *container, > + MemoryRegionSection *section) > +{ > + RamDiscardMgr *rdm = memory_region_get_ram_discard_mgr(section->mr); > + RamDiscardMgrClass *rdmc = RAM_DISCARD_MGR_GET_CLASS(rdm); > + VFIORamDiscardListener tmp_vrdl, *vrdl = NULL; > + > + QLIST_FOREACH(vrdl, &container->vrdl_list, next) { > + if (vrdl->mr == section->mr && > + vrdl->offset_within_region == section->offset_within_region) { > + break; > + } > + } > + > + if (!vrdl) { > + hw_error("vfio: Trying to sync missing RAM discard listener"); > + } > + > + tmp_vrdl = *vrdl; > + ram_discard_listener_init(&tmp_vrdl.listener, > + vfio_ram_discard_notify_dirty_bitmap, NULL, NULL); > + return rdmc->replay_populated(rdm, section->mr, &tmp_vrdl.listener); > +} > + > static int vfio_sync_dirty_bitmap(VFIOContainer *container, > MemoryRegionSection *section) > { > @@ -1138,6 +1346,8 @@ static int vfio_sync_dirty_bitmap(VFIOContainer *container, > } > } > return 0; > + } else if (memory_region_has_ram_discard_mgr(section->mr)) { > + return vfio_sync_ram_discard_listener_dirty_bitmap(container, section); > } > > ram_addr = memory_region_get_ram_addr(section->mr) + > @@ -1768,6 +1978,7 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as, > container->dma_max = 0; > QLIST_INIT(&container->giommu_list); > QLIST_INIT(&container->hostwin_list); > + QLIST_INIT(&container->vrdl_list); > > ret = vfio_init_container(container, group->fd, errp); > if (ret) { > diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h > index fed0e85f66..fba5a14c8b 100644 > --- a/include/hw/vfio/vfio-common.h > +++ b/include/hw/vfio/vfio-common.h > @@ -93,6 +93,7 @@ typedef struct VFIOContainer { > QLIST_HEAD(, VFIOGuestIOMMU) giommu_list; > QLIST_HEAD(, VFIOHostDMAWindow) hostwin_list; > QLIST_HEAD(, VFIOGroup) group_list; > + QLIST_HEAD(, VFIORamDiscardListener) vrdl_list; > QLIST_ENTRY(VFIOContainer) next; > } VFIOContainer; > > @@ -104,6 +105,18 @@ typedef struct VFIOGuestIOMMU { > QLIST_ENTRY(VFIOGuestIOMMU) giommu_next; > } VFIOGuestIOMMU; > > +typedef struct VFIORamDiscardListener { > + VFIOContainer *container; > + MemoryRegion *mr; > + hwaddr offset_within_region; > + hwaddr offset_within_address_space; > + hwaddr size; > + uint64_t granularity; > + unsigned long dma_max; > + RamDiscardListener listener; > + QLIST_ENTRY(VFIORamDiscardListener) next; > +} VFIORamDiscardListener; > + > typedef struct VFIOHostDMAWindow { > hwaddr min_iova; > hwaddr max_iova;