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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 DAD4CC43331 for ; Mon, 30 Mar 2020 02:24:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A9C7E20578 for ; Mon, 30 Mar 2020 02:24:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728490AbgC3CYp (ORCPT ); Sun, 29 Mar 2020 22:24:45 -0400 Received: from mga09.intel.com ([134.134.136.24]:63642 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728107AbgC3CYp (ORCPT ); Sun, 29 Mar 2020 22:24:45 -0400 IronPort-SDR: RUqQbK1zEQDLRDtPcagufz+JeFZ23HS/p4MqUQ0yytV2wIC5JcD0vk+MNo+HmcMJmnnd5PIY0/ AborXCWT8AYg== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Mar 2020 19:24:44 -0700 IronPort-SDR: LNQIuW64wDlZVPiKJn63DVtJ/4DNuUQCARCuBcqiUEX2HuSoubJXLUtXjhIkmRiR8EvUBy4uVh ATXPTOhCKy5A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,322,1580803200"; d="scan'208";a="272224977" Received: from joy-optiplex-7040.sh.intel.com (HELO joy-OptiPlex-7040) ([10.239.13.16]) by fmsmga004.fm.intel.com with ESMTP; 29 Mar 2020 19:24:39 -0700 Date: Sun, 29 Mar 2020 22:15:06 -0400 From: Yan Zhao To: Kirti Wankhede Cc: "alex.williamson@redhat.com" , "cjia@nvidia.com" , "Tian, Kevin" , "Yang, Ziye" , "Liu, Changpeng" , "Liu, Yi L" , "mlevitsk@redhat.com" , "eskultet@redhat.com" , "cohuck@redhat.com" , "dgilbert@redhat.com" , "jonathan.davies@nutanix.com" , "eauger@redhat.com" , "aik@ozlabs.ru" , "pasic@linux.ibm.com" , "felipe@nutanix.com" , "Zhengxiao.zx@Alibaba-inc.com" , "shuangtai.tst@alibaba-inc.com" , "Ken.Xue@amd.com" , "Wang, Zhi A" , "qemu-devel@nongnu.org" , "kvm@vger.kernel.org" Subject: Re: [PATCH v16 Kernel 5/7] vfio iommu: Update UNMAP_DMA ioctl to get dirty bitmap before unmap Message-ID: <20200330021506.GC30683@joy-OptiPlex-7040> Reply-To: Yan Zhao References: <1585078359-20124-1-git-send-email-kwankhede@nvidia.com> <1585078359-20124-6-git-send-email-kwankhede@nvidia.com> <20200325021800.GC20109@joy-OptiPlex-7040> <3cabb357-b9c5-f8b3-5d57-1178ec0dde5a@nvidia.com> <20200327000426.GA26419@joy-OptiPlex-7040> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Mar 27, 2020 at 12:42:43PM +0800, Kirti Wankhede wrote: > > > On 3/27/2020 5:34 AM, Yan Zhao wrote: > > On Fri, Mar 27, 2020 at 05:39:44AM +0800, Kirti Wankhede wrote: > >> > >> > >> On 3/25/2020 7:48 AM, Yan Zhao wrote: > >>> On Wed, Mar 25, 2020 at 03:32:37AM +0800, Kirti Wankhede wrote: > >>>> DMA mapped pages, including those pinned by mdev vendor drivers, might > >>>> get unpinned and unmapped while migration is active and device is still > >>>> running. For example, in pre-copy phase while guest driver could access > >>>> those pages, host device or vendor driver can dirty these mapped pages. > >>>> Such pages should be marked dirty so as to maintain memory consistency > >>>> for a user making use of dirty page tracking. > >>>> > >>>> To get bitmap during unmap, user should allocate memory for bitmap, set > >>>> size of allocated memory, set page size to be considered for bitmap and > >>>> set flag VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP. > >>>> > >>>> Signed-off-by: Kirti Wankhede > >>>> Reviewed-by: Neo Jia > >>>> --- > >>>> drivers/vfio/vfio_iommu_type1.c | 54 ++++++++++++++++++++++++++++++++++++++--- > >>>> include/uapi/linux/vfio.h | 10 ++++++++ > >>>> 2 files changed, 60 insertions(+), 4 deletions(-) > >>>> > >>>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > >>>> index 27ed069c5053..b98a8d79e13a 100644 > >>>> --- a/drivers/vfio/vfio_iommu_type1.c > >>>> +++ b/drivers/vfio/vfio_iommu_type1.c > >>>> @@ -982,7 +982,8 @@ static int verify_bitmap_size(uint64_t npages, uint64_t bitmap_size) > >>>> } > >>>> > >>>> static int vfio_dma_do_unmap(struct vfio_iommu *iommu, > >>>> - struct vfio_iommu_type1_dma_unmap *unmap) > >>>> + struct vfio_iommu_type1_dma_unmap *unmap, > >>>> + struct vfio_bitmap *bitmap) > >>>> { > >>>> uint64_t mask; > >>>> struct vfio_dma *dma, *dma_last = NULL; > >>>> @@ -1033,6 +1034,10 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu, > >>>> * will be returned if these conditions are not met. The v2 interface > >>>> * will only return success and a size of zero if there were no > >>>> * mappings within the range. > >>>> + * > >>>> + * When VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP flag is set, unmap request > >>>> + * must be for single mapping. Multiple mappings with this flag set is > >>>> + * not supported. > >>>> */ > >>>> if (iommu->v2) { > >>>> dma = vfio_find_dma(iommu, unmap->iova, 1); > >>>> @@ -1040,6 +1045,13 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu, > >>>> ret = -EINVAL; > >>>> goto unlock; > >>>> } > >>>> + > >>>> + if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) && > >>>> + (dma->iova != unmap->iova || dma->size != unmap->size)) { > >>> potential NULL pointer! > >>> > >>> And could you address the comments in v14? > >>> How to handle DSI unmaps in vIOMMU > >>> (https://lore.kernel.org/kvm/20200323011041.GB5456@joy-OptiPlex-7040/) > >>> > >> > >> Sorry, I drafted reply to it, but I missed to send, it remained in my drafts > >> > >> > > >> > it happens in vIOMMU Domain level invalidation of IOTLB > >> > (domain-selective invalidation, see vtd_iotlb_domain_invalidate() in > >> qemu). > >> > common in VTD lazy mode, and NOT just happening once at boot time. > >> > rather than invalidate page by page, it batches the page invalidation. > >> > so, when this invalidation takes place, even higher level page tables > >> > have been invalid and therefore it has to invalidate a bigger > >> combined range. > >> > That's why we see IOVAs are mapped in 4k pages, but are unmapped in 2M > >> > pages. > >> > > >> > I think those UNMAPs should also have GET_DIRTY_BIMTAP flag on, right? > >> > >> > >> vtd_iotlb_domain_invalidate() > >> vtd_sync_shadow_page_table() > >> vtd_sync_shadow_page_table_range(vtd_as, &ce, 0, UINT64_MAX) > >> vtd_page_walk() > >> vtd_page_walk_level() - walk over specific level for IOVA range > >> vtd_page_walk_one() > >> memory_region_notify_iommu() > >> ... > >> vfio_iommu_map_notify() > >> > >> In the above trace, isn't page walk will take care of creating proper > >> IOTLB entry which should be same as created during mapping for that > >> IOTLB entry? > >> > > No. It does walk the page table, but as it's dsi (delay & batched unmap), > > pages table entry for a whole 2M (the higher level, not last level for 4K) > > range is invalid, so the iotlb->addr_mask what vfio_iommu_map_notify() > > receives is (2M - 1), not the same as the size for map. > > > > When do this happen? during my testing I never hit this case. How can I > hit this case? Just common settings to enable vIOMMU: Qemu: -device intel-iommu,caching-mode=true guest kernel parameter: intel_iommu=on (intel_iommu=on turns on lazy mode by default) In lazy mode, guest notifies DMA MAP on page level, but notifies DMA UNMAPs in batch. with a pass-through NVMe, there are 89 DSI unmaps in 1 second for a typical fio. With a pass-through GPU, there 22 DSI unmaps in total for benchmark openArena (lasting around 55 secs) > > In this case, will adjacent whole vfio_dmas will be clubbed together or > will there be any intersection of vfio_dmas? > clubbed together.