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, 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 61371C43331 for ; Fri, 27 Mar 2020 00:14:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 32CB4206E6 for ; Fri, 27 Mar 2020 00:14:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727731AbgC0AOE (ORCPT ); Thu, 26 Mar 2020 20:14:04 -0400 Received: from mga04.intel.com ([192.55.52.120]:41315 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727683AbgC0AOE (ORCPT ); Thu, 26 Mar 2020 20:14:04 -0400 IronPort-SDR: x7ysgOs55nWluH8C6s6NK8IhG1J6okS8RdaOcnx+gIdEHmXypmlVOI4WYi/wHYDA1/fSjSJLV0 /v+QFKqOKx+Q== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Mar 2020 17:14:03 -0700 IronPort-SDR: mEe5Qq74slYzR5lwKOwReqjluzzJrAwiFd7oFDZQ1uhd71nnDNh5mTuGmUSj10eN0sTXvBmKaN uhXtwX/2zpgg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,310,1580803200"; d="scan'208";a="271372032" Received: from joy-optiplex-7040.sh.intel.com (HELO joy-OptiPlex-7040) ([10.239.13.16]) by fmsmga004.fm.intel.com with ESMTP; 26 Mar 2020 17:13:59 -0700 Date: Thu, 26 Mar 2020 20:04:27 -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: <20200327000426.GA26419@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3cabb357-b9c5-f8b3-5d57-1178ec0dde5a@nvidia.com> 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 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. > > >>> > >>> Such unmap would callback vfio_iommu_map_notify() in QEMU. In > >>> vfio_iommu_map_notify(), unmap is called on same range >>> iotlb->addr_mask + 1> which was used for map. Secondly unmap with > bitmap > >>> will be called only when device state has _SAVING flag set. > >> > > in this case, iotlb->addr_mask in unmap is 0x200000 -1. > > different than 0x1000 -1 used for map. > >> It might be helpful for Yan, and everyone else, to see the latest QEMU > >> patch series. Thanks, > >> > > yes, please. also curious of log_sync part for vIOMMU. given most > IOVAs in > > address space are unmapped and therefore no IOTLBs are able to be found. > > > > Qemu patches compatible with v16 version are at: > https://www.mail-archive.com/qemu-devel@nongnu.org/msg691806.html > >