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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 541B9C43331 for ; Fri, 27 Mar 2020 04:43:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1912620705 for ; Fri, 27 Mar 2020 04:43:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="bpH+uPvE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726027AbgC0EnF (ORCPT ); Fri, 27 Mar 2020 00:43:05 -0400 Received: from hqnvemgate26.nvidia.com ([216.228.121.65]:1530 "EHLO hqnvemgate26.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725904AbgC0EnE (ORCPT ); Fri, 27 Mar 2020 00:43:04 -0400 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Thu, 26 Mar 2020 21:42:51 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Thu, 26 Mar 2020 21:43:04 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Thu, 26 Mar 2020 21:43:04 -0700 Received: from [10.40.103.35] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Fri, 27 Mar 2020 04:42:49 +0000 Subject: Re: [PATCH v16 Kernel 5/7] vfio iommu: Update UNMAP_DMA ioctl to get dirty bitmap before unmap To: Yan Zhao 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" 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> X-Nvconfidentiality: public From: Kirti Wankhede Message-ID: Date: Fri, 27 Mar 2020 10:12:43 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200327000426.GA26419@joy-OptiPlex-7040> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL111.nvidia.com (172.20.187.18) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1585284171; bh=/eY4Cemp7k65d1UPvele9vg+mEFz5dD6zNLRY1EZk+M=; h=X-PGP-Universal:Subject:To:CC:References:X-Nvconfidentiality:From: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=bpH+uPvEyUV9/yopyYsw/ETv09Dfm7eNzbeuiHMbX9QJRDDqXS0nJJ/8/vlPKXphk QwL/ndoLw0bB/2UePXTELBAsIQ/tg0TqM75KuOfkUo9dlOF8UFk51oRawBGOOiq9jb Epy37JFPJW44MZDMU9fi3CUMHbW4oeA3Jz1wVm79syRAkY5AFekpgViL9aGNsyyMjW ak10pYyaVtO9EHsphoCHX4PtpbZSGvAIGSCKKNi7tIw+50abG5J4I/j+szCs1t/L5O qOwXQLpdzR2cwQ9NTXMaC4kqgfmi+67fcftNG6+PHqgKjlXL8UWrlgT+tvYO4LysxF 2LEyGwOnrxf1A== Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org 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? In this case, will adjacent whole vfio_dmas will be clubbed together or will there be any intersection of vfio_dmas? Thanks, Kirti