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=-7.0 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 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 A6EC9C43331 for ; Tue, 31 Mar 2020 19:06:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 802DF2137B for ; Tue, 31 Mar 2020 19:06:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="UrL4uPs+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727768AbgCaTGf (ORCPT ); Tue, 31 Mar 2020 15:06:35 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:39202 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726315AbgCaTGf (ORCPT ); Tue, 31 Mar 2020 15:06:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585681594; 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=tgxHMDFHS7EdhZt/y8v9VvwjbCh3+IDnijixAq81LLE=; b=UrL4uPs+/MX9qxvHB79wTh14/aN5ljquqM4PVK1eOJ6jUAyA4x6Bbovp5sWUKCjUcyrM+K oldI9B8wCQQ0NEPqpZs9EUZyr9C93VIM/3hyS1bvR2jwUSLuDd9fJdbi1Laq8iSS0LyfuY DjTEcScbL2mHY237htxXjSdqRAgduTU= 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-303-uqrVF3hiNaKxOqicctyvDQ-1; Tue, 31 Mar 2020 15:06:30 -0400 X-MC-Unique: uqrVF3hiNaKxOqicctyvDQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C7B288017CC; Tue, 31 Mar 2020 19:06:27 +0000 (UTC) Received: from w520.home (ovpn-112-162.phx2.redhat.com [10.3.112.162]) by smtp.corp.redhat.com (Postfix) with ESMTP id 889775C1BB; Tue, 31 Mar 2020 19:06:25 +0000 (UTC) Date: Tue, 31 Mar 2020 13:06:25 -0600 From: Alex Williamson To: Kirti Wankhede Cc: , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v17 Kernel 5/7] vfio iommu: Update UNMAP_DMA ioctl to get dirty bitmap before unmap Message-ID: <20200331130625.77851747@w520.home> In-Reply-To: <66af06b5-4e87-9f7a-be85-08a68d6ab982@nvidia.com> References: <1585587044-2408-1-git-send-email-kwankhede@nvidia.com> <1585587044-2408-6-git-send-email-kwankhede@nvidia.com> <20200330153421.6246c2c6@w520.home> <66af06b5-4e87-9f7a-be85-08a68d6ab982@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, 1 Apr 2020 00:16:13 +0530 Kirti Wankhede wrote: > On 3/31/2020 3:04 AM, Alex Williamson wrote: > > On Mon, 30 Mar 2020 22:20:42 +0530 > > 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 | 55 ++++++++++++++++++++++++++++++++++++++--- > >> include/uapi/linux/vfio.h | 10 ++++++++ > >> 2 files changed, 61 insertions(+), 4 deletions(-) > >> > >> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > >> index 5efebc2b60e1..266550bd7307 100644 > >> --- a/drivers/vfio/vfio_iommu_type1.c > >> +++ b/drivers/vfio/vfio_iommu_type1.c > >> @@ -983,7 +983,8 @@ 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; > >> @@ -1034,6 +1035,10 @@ 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); > >> @@ -1041,6 +1046,14 @@ 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 && > >> + (dma->iova != unmap->iova || dma->size != unmap->size)) { > > > > > > I think your intention was to return error if the user asked for the > > dirty bitmap and the requested unmap range doesn't exactly match the > > vfio_dma. Not finding a vfio_dma should therefore also be an error. > > For example, if we had a single mapping at {0x1000-0x1fff} and the user > > unmapped with dirty bitmap {0x0-0x2fff}, that should return an error, > > but it's not caught by the above because there is no vfio_dma @0x0. > > Therefore I think you want: > > > > ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) && > > (!dma || dma->iova != unmap->iova || dma->size != unmap->size)) > > > > Right? Thanks, > > > > > Yes, updating check. > > Is !dma here also error case when VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP > flag is not set? No it's not. > DMA_UNMAP ioctl returns how much was unmapped, from user space > perspective this would be from start of range (unmap->iova), right? It's the actual amount of memory that was unmapped within the provided range, without getting the dirty bitmap the range doesn't need to start or end at a vfio_dma, it just cannot bisect a vfio_dma. Thanks, Alex