From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=cIHa=5F=nongnu.org=qemu-devel-bounces+qemu-devel=archiver.kernel.org@kernel.org>
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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED,
	HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,
	SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable
	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 B7029C4332B
	for <qemu-devel@archiver.kernel.org>; Fri, 20 Mar 2020 17:50:40 +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 74D5E20663
	for <qemu-devel@archiver.kernel.org>; Fri, 20 Mar 2020 17:50:40 +0000 (UTC)
Authentication-Results: mail.kernel.org;
	dkim=fail reason="signature verification failed" (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="aQ6d2diF"
DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 74D5E20663
Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com
Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org
Received: from localhost ([::1]:57114 helo=lists1p.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.90_1)
	(envelope-from <qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org>)
	id 1jFLn5-0006UF-Kp
	for qemu-devel@archiver.kernel.org; Fri, 20 Mar 2020 13:50:39 -0400
Received: from eggs.gnu.org ([2001:470:142:3::10]:37068)
 by lists.gnu.org with esmtp (Exim 4.90_1)
 (envelope-from <kwankhede@nvidia.com>) id 1jFLm1-0005XB-L5
 for qemu-devel@nongnu.org; Fri, 20 Mar 2020 13:49:36 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
 (envelope-from <kwankhede@nvidia.com>) id 1jFLly-0006tE-Ia
 for qemu-devel@nongnu.org; Fri, 20 Mar 2020 13:49:32 -0400
Received: from hqnvemgate26.nvidia.com ([216.228.121.65]:9161)
 by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32)
 (Exim 4.71) (envelope-from <kwankhede@nvidia.com>)
 id 1jFLly-0006sf-1o
 for qemu-devel@nongnu.org; Fri, 20 Mar 2020 13:49:30 -0400
Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by
 hqnvemgate26.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA)
 id <B5e75021a0000>; Fri, 20 Mar 2020 10:49:14 -0700
Received: from hqmail.nvidia.com ([172.20.161.6])
 by hqpgpgate102.nvidia.com (PGP Universal service);
 Fri, 20 Mar 2020 10:49:27 -0700
X-PGP-Universal: processed;
 by hqpgpgate102.nvidia.com on Fri, 20 Mar 2020 10:49:27 -0700
Received: from [10.40.103.10] (172.20.13.39) by HQMAIL107.nvidia.com
 (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Fri, 20 Mar
 2020 17:49:18 +0000
Subject: Re: [PATCH v15 Kernel 4/7] vfio iommu: Implementation of ioctl for
 dirty pages tracking.
To: Alex Williamson <alex.williamson@redhat.com>
References: <1584649004-8285-1-git-send-email-kwankhede@nvidia.com>
 <1584649004-8285-5-git-send-email-kwankhede@nvidia.com>
 <20200319165704.1f4eb36a@w520.home>
X-Nvconfidentiality: public
From: Kirti Wankhede <kwankhede@nvidia.com>
Message-ID: <bc48ae5c-67f9-d95e-5d60-6c42359bb790@nvidia.com>
Date: Fri, 20 Mar 2020 23:19:14 +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: <20200319165704.1f4eb36a@w520.home>
X-Originating-IP: [172.20.13.39]
X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) 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=1584726554; bh=cNc9XktQWUndzaPks54ysmPgqavRVnjyBmMhwCNm1xY=;
 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=aQ6d2diFe3Cp6aj4/tHxxCjOG1vyWs+vyTgzHeeHsEb9xaAAsY9f+CFN/aaS+KMbW
 /me+MhYWxrAIeMJE+WgUtOY/WdmapWm8/8qd07+ZYfg6hVmuEn+i4K4xGS50sWrqK6
 DaSVG8V7Y/WD9p8B+qjbAIdxFYUz+xPYiObTcDwBVhiURi7kF17YgJoEZTGwfKHpe9
 0TXhiEsX8ANa2WQj+PMFyklPzBsljK+Ez9+n1tmqpQdjtWnlu5ov3VOpfSZlUly4gh
 fNmw2xRtSAhU+2LS1wLOLEEyhcz1636QE9E1c10k0yYYbRkgUO33vfn8xql99Yhs7q
 XuIbnRwDoDOFg==
X-detected-operating-system: by eggs.gnu.org: Windows 7 or 8 [fuzzy]
X-Received-From: 216.228.121.65
X-BeenThere: qemu-devel@nongnu.org
X-Mailman-Version: 2.1.23
Precedence: list
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
 <mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <https://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
 <mailto:qemu-devel-request@nongnu.org?subject=subscribe>
Cc: Zhengxiao.zx@Alibaba-inc.com, kevin.tian@intel.com, yi.l.liu@intel.com,
 cjia@nvidia.com, kvm@vger.kernel.org, eskultet@redhat.com, ziye.yang@intel.com,
 qemu-devel@nongnu.org, cohuck@redhat.com, shuangtai.tst@alibaba-inc.com,
 dgilbert@redhat.com, zhi.a.wang@intel.com, mlevitsk@redhat.com,
 pasic@linux.ibm.com, aik@ozlabs.ru, eauger@redhat.com, felipe@nutanix.com,
 jonathan.davies@nutanix.com, yan.y.zhao@intel.com, changpeng.liu@intel.com,
 Ken.Xue@amd.com
Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org
Sender: "Qemu-devel"
 <qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org>



On 3/20/2020 4:27 AM, Alex Williamson wrote:
> On Fri, 20 Mar 2020 01:46:41 +0530
> Kirti Wankhede <kwankhede@nvidia.com> wrote:
> 
>> VFIO_IOMMU_DIRTY_PAGES ioctl performs three operations:
>> - Start dirty pages tracking while migration is active
>> - Stop dirty pages tracking.
>> - Get dirty pages bitmap. Its user space application's responsibility to
>>    copy content of dirty pages from source to destination during migration.
>>
>> To prevent DoS attack, memory for bitmap is allocated per vfio_dma
>> structure. Bitmap size is calculated considering smallest supported page
>> size. Bitmap is allocated for all vfio_dmas when dirty logging is enabled
>>
>> Bitmap is populated for already pinned pages when bitmap is allocated for
>> a vfio_dma with the smallest supported page size. Update bitmap from
>> pinning functions when tracking is enabled. When user application queries
>> bitmap, check if requested page size is same as page size used to
>> populated bitmap. If it is equal, copy bitmap, but if not equal, return
>> error.
>>
>> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
>> Reviewed-by: Neo Jia <cjia@nvidia.com>
>> ---
>>   drivers/vfio/vfio_iommu_type1.c | 242 +++++++++++++++++++++++++++++++++++++++-
>>   1 file changed, 236 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
>> index 70aeab921d0f..239f61764d03 100644
>> --- a/drivers/vfio/vfio_iommu_type1.c
>> +++ b/drivers/vfio/vfio_iommu_type1.c
>> @@ -71,6 +71,7 @@ struct vfio_iommu {
>>   	unsigned int		dma_avail;
>>   	bool			v2;
>>   	bool			nesting;
>> +	bool			dirty_page_tracking;
>>   };
>>   
>>   struct vfio_domain {
>> @@ -91,6 +92,7 @@ struct vfio_dma {
>>   	bool			lock_cap;	/* capable(CAP_IPC_LOCK) */
>>   	struct task_struct	*task;
>>   	struct rb_root		pfn_list;	/* Ex-user pinned pfn list */
>> +	unsigned long		*bitmap;
>>   };
>>   
>>   struct vfio_group {
>> @@ -125,7 +127,21 @@ struct vfio_regions {
>>   #define IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)	\
>>   					(!list_empty(&iommu->domain_list))
>>   
>> +#define DIRTY_BITMAP_BYTES(n)	(ALIGN(n, BITS_PER_TYPE(u64)) / BITS_PER_BYTE)
>> +
>> +/*
>> + * Input argument of number of bits to bitmap_set() is unsigned integer, which
>> + * further casts to signed integer for unaligned multi-bit operation,
>> + * __bitmap_set().
>> + * Then maximum bitmap size supported is 2^31 bits divided by 2^3 bits/byte,
>> + * that is 2^28 (256 MB) which maps to 2^31 * 2^12 = 2^43 (8TB) on 4K page
>> + * system.
>> + */
>> +#define DIRTY_BITMAP_PAGES_MAX	((1UL << 31) - 1)
>> +#define DIRTY_BITMAP_SIZE_MAX	 DIRTY_BITMAP_BYTES(DIRTY_BITMAP_PAGES_MAX)
>> +
>>   static int put_pfn(unsigned long pfn, int prot);
>> +static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu);
>>   
>>   /*
>>    * This code handles mapping and unmapping of user data buffers
>> @@ -175,6 +191,67 @@ static void vfio_unlink_dma(struct vfio_iommu *iommu, struct vfio_dma *old)
>>   	rb_erase(&old->node, &iommu->dma_list);
>>   }
>>   
>> +
>> +static int vfio_dma_bitmap_alloc(struct vfio_dma *dma, uint64_t pgsize)
>> +{
>> +	uint64_t npages = dma->size / pgsize;
>> +
> 
> Shouldn't we test this against one of the MAX macros defined above?  It
> would be bad if we could enabled dirty tracking but not allow the user
> to retrieve it.
> 

Yes, adding check as below:

         if (npages > DIRTY_BITMAP_PAGES_MAX)
                 -EINVAL;


>> +	dma->bitmap = kvzalloc(DIRTY_BITMAP_BYTES(npages), GFP_KERNEL);
>> +	if (!dma->bitmap)
>> +		return -ENOMEM;
>> +
>> +	return 0;
>> +}
>> +
>> +static int vfio_dma_bitmap_alloc_all(struct vfio_iommu *iommu, uint64_t pgsize)
>> +{
>> +	struct rb_node *n = rb_first(&iommu->dma_list);
>> +
>> +	for (; n; n = rb_next(n)) {
>> +		struct vfio_dma *dma = rb_entry(n, struct vfio_dma, node);
>> +		struct rb_node *p;
>> +		int ret;
>> +
>> +		ret = vfio_dma_bitmap_alloc(dma, pgsize);
>> +		if (ret) {
>> +			struct rb_node *p = rb_prev(n);
>> +
>> +			for (; p; p = rb_prev(p)) {
>> +				struct vfio_dma *dma = rb_entry(n,
>> +							struct vfio_dma, node);
>> +
>> +				kfree(dma->bitmap);
>> +				dma->bitmap = NULL;
>> +			}
>> +			return ret;
>> +		}
>> +
>> +		if (RB_EMPTY_ROOT(&dma->pfn_list))
>> +			continue;
>> +
>> +		for (p = rb_first(&dma->pfn_list); p; p = rb_next(p)) {
>> +			struct vfio_pfn *vpfn = rb_entry(p, struct vfio_pfn,
>> +							 node);
>> +
>> +			bitmap_set(dma->bitmap,
>> +				   (vpfn->iova - dma->iova) / pgsize, 1);
>> +		}
>> +	}
>> +	return 0;
>> +}
>> +
>> +static void vfio_dma_bitmap_free_all(struct vfio_iommu *iommu)
>> +{
>> +	struct rb_node *n = rb_first(&iommu->dma_list);
>> +
>> +	for (; n; n = rb_next(n)) {
>> +		struct vfio_dma *dma = rb_entry(n, struct vfio_dma, node);
>> +
>> +		kfree(dma->bitmap);
>> +		dma->bitmap = NULL;
> 
> Might be useful to have a vfio_dma_bitmap_free() for here and above.
> 

Ok.

>> +	}
>> +}
>> +
>>   /*
>>    * Helper Functions for host iova-pfn list
>>    */
>> @@ -567,6 +644,14 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
>>   			vfio_unpin_page_external(dma, iova, do_accounting);
>>   			goto pin_unwind;
>>   		}
>> +
>> +		if (iommu->dirty_page_tracking) {
>> +			unsigned long pgshift =
>> +					 __ffs(vfio_pgsize_bitmap(iommu));
>> +
>> +			bitmap_set(dma->bitmap,
>> +				   (vpfn->iova - dma->iova) >> pgshift, 1);
>> +		}
>>   	}
>>   
>>   	ret = i;
>> @@ -801,6 +886,7 @@ static void vfio_remove_dma(struct vfio_iommu *iommu, struct vfio_dma *dma)
>>   	vfio_unmap_unpin(iommu, dma, true);
>>   	vfio_unlink_dma(iommu, dma);
>>   	put_task_struct(dma->task);
>> +	kfree(dma->bitmap);
>>   	kfree(dma);
>>   	iommu->dma_avail++;
>>   }
>> @@ -831,6 +917,50 @@ static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu)
>>   	return bitmap;
>>   }
>>   
>> +static int vfio_iova_dirty_bitmap(struct vfio_iommu *iommu, dma_addr_t iova,
>> +				  size_t size, uint64_t pgsize,
>> +				  u64 __user *bitmap)
>> +{
>> +	struct vfio_dma *dma;
>> +	unsigned long pgshift = __ffs(pgsize);
>> +	unsigned int npages, bitmap_size;
>> +
>> +	dma = vfio_find_dma(iommu, iova, 1);
>> +
>> +	if (!dma)
>> +		return -EINVAL;
>> +
>> +	if (dma->iova != iova || dma->size != size)
>> +		return -EINVAL;
>> +
>> +	npages = dma->size >> pgshift;
>> +	bitmap_size = DIRTY_BITMAP_BYTES(npages);
>> +
>> +	/* mark all pages dirty if all pages are pinned and mapped. */
>> +	if (dma->iommu_mapped)
>> +		bitmap_set(dma->bitmap, 0, npages);
>> +
>> +	if (copy_to_user((void __user *)bitmap, dma->bitmap, bitmap_size))
>> +		return -EFAULT;
> 
> We still need to reset the bitmap here, clearing and re-adding the
> pages that are still pinned.
> 
> https://lore.kernel.org/kvm/20200319070635.2ff5db56@x1.home/
> 

I thought you agreed on my reply to it
https://lore.kernel.org/kvm/31621b70-02a9-2ea5-045f-f72b671fe703@nvidia.com/

 > Why re-populate when there will be no change since
 > vfio_iova_dirty_bitmap() is called holding iommu->lock? If there is any
 > pin request while vfio_iova_dirty_bitmap() is still working, it will
 > wait till iommu->lock is released. Bitmap will be populated when page is
 > pinned.

Thanks,
Kirti

>> +
>> +	return 0;
>> +}
>> +
>> +static int verify_bitmap_size(uint64_t npages, uint64_t bitmap_size)
>> +{
>> +	uint64_t bsize;
>> +
>> +	if (!npages || !bitmap_size || (bitmap_size > DIRTY_BITMAP_SIZE_MAX))
>> +		return -EINVAL;
>> +
>> +	bsize = DIRTY_BITMAP_BYTES(npages);
>> +
>> +	if (bitmap_size < bsize)
>> +		return -EINVAL;
>> +
>> +	return 0;
>> +}
>> +
>>   static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>>   			     struct vfio_iommu_type1_dma_unmap *unmap)
>>   {
>> @@ -1038,16 +1168,16 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
>>   	unsigned long vaddr = map->vaddr;
>>   	size_t size = map->size;
>>   	int ret = 0, prot = 0;
>> -	uint64_t mask;
>> +	uint64_t pgsize;
>>   	struct vfio_dma *dma;
>>   
>>   	/* Verify that none of our __u64 fields overflow */
>>   	if (map->size != size || map->vaddr != vaddr || map->iova != iova)
>>   		return -EINVAL;
>>   
>> -	mask = ((uint64_t)1 << __ffs(vfio_pgsize_bitmap(iommu))) - 1;
>> +	pgsize = (uint64_t)1 << __ffs(vfio_pgsize_bitmap(iommu));
>>   
>> -	WARN_ON(mask & PAGE_MASK);
>> +	WARN_ON((pgsize - 1) & PAGE_MASK);
>>   
>>   	/* READ/WRITE from device perspective */
>>   	if (map->flags & VFIO_DMA_MAP_FLAG_WRITE)
>> @@ -1055,7 +1185,7 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
>>   	if (map->flags & VFIO_DMA_MAP_FLAG_READ)
>>   		prot |= IOMMU_READ;
>>   
>> -	if (!prot || !size || (size | iova | vaddr) & mask)
>> +	if (!prot || !size || (size | iova | vaddr) & (pgsize - 1))
>>   		return -EINVAL;
>>   
>>   	/* Don't allow IOVA or virtual address wrap */
>> @@ -1130,6 +1260,12 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
>>   	else
>>   		ret = vfio_pin_map_dma(iommu, dma, size);
>>   
>> +	if (!ret && iommu->dirty_page_tracking) {
>> +		ret = vfio_dma_bitmap_alloc(dma, pgsize);
>> +		if (ret)
>> +			vfio_remove_dma(iommu, dma);
>> +	}
>> +
>>   out_unlock:
>>   	mutex_unlock(&iommu->lock);
>>   	return ret;
>> @@ -2278,6 +2414,93 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
>>   
>>   		return copy_to_user((void __user *)arg, &unmap, minsz) ?
>>   			-EFAULT : 0;
>> +	} else if (cmd == VFIO_IOMMU_DIRTY_PAGES) {
>> +		struct vfio_iommu_type1_dirty_bitmap dirty;
>> +		uint32_t mask = VFIO_IOMMU_DIRTY_PAGES_FLAG_START |
>> +				VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP |
>> +				VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP;
>> +		int ret = 0;
>> +
>> +		if (!iommu->v2)
>> +			return -EACCES;
>> +
>> +		minsz = offsetofend(struct vfio_iommu_type1_dirty_bitmap,
>> +				    flags);
>> +
>> +		if (copy_from_user(&dirty, (void __user *)arg, minsz))
>> +			return -EFAULT;
>> +
>> +		if (dirty.argsz < minsz || dirty.flags & ~mask)
>> +			return -EINVAL;
>> +
>> +		/* only one flag should be set at a time */
>> +		if (__ffs(dirty.flags) != __fls(dirty.flags))
>> +			return -EINVAL;
>> +
>> +		if (dirty.flags & VFIO_IOMMU_DIRTY_PAGES_FLAG_START) {
>> +			uint64_t pgsize = 1 << __ffs(vfio_pgsize_bitmap(iommu));
>> +
>> +			mutex_lock(&iommu->lock);
>> +			if (!iommu->dirty_page_tracking) {
>> +				ret = vfio_dma_bitmap_alloc_all(iommu, pgsize);
>> +				if (!ret)
>> +					iommu->dirty_page_tracking = true;
>> +			}
>> +			mutex_unlock(&iommu->lock);
>> +			return ret;
>> +		} else if (dirty.flags & VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP) {
>> +			mutex_lock(&iommu->lock);
>> +			if (iommu->dirty_page_tracking) {
>> +				iommu->dirty_page_tracking = false;
>> +				vfio_dma_bitmap_free_all(iommu);
>> +			}
>> +			mutex_unlock(&iommu->lock);
>> +			return 0;
>> +		} else if (dirty.flags &
>> +				 VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP) {
>> +			struct vfio_iommu_type1_dirty_bitmap_get range;
>> +			unsigned long pgshift;
>> +			size_t data_size = dirty.argsz - minsz;
>> +			uint64_t iommu_pgsize =
>> +					 1 << __ffs(vfio_pgsize_bitmap(iommu));
>> +
>> +			if (!data_size || data_size < sizeof(range))
>> +				return -EINVAL;
>> +
>> +			if (copy_from_user(&range, (void __user *)(arg + minsz),
>> +					   sizeof(range)))
>> +				return -EFAULT;
>> +
>> +			/* allow only min supported pgsize */
>> +			if (range.bitmap.pgsize != iommu_pgsize)
>> +				return -EINVAL;
>> +			if (range.iova & (iommu_pgsize - 1))
>> +				return -EINVAL;
>> +			if (!range.size || range.size & (iommu_pgsize - 1))
>> +				return -EINVAL;
>> +			if (range.iova + range.size < range.iova)
>> +				return -EINVAL;
>> +			if (!access_ok((void __user *)range.bitmap.data,
>> +				       range.bitmap.size))
>> +				return -EINVAL;
>> +
>> +			pgshift = __ffs(range.bitmap.pgsize);
>> +			ret = verify_bitmap_size(range.size >> pgshift,
>> +						 range.bitmap.size);
>> +			if (ret)
>> +				return ret;
>> +
>> +			mutex_lock(&iommu->lock);
>> +			if (iommu->dirty_page_tracking)
>> +				ret = vfio_iova_dirty_bitmap(iommu, range.iova,
>> +						range.size, range.bitmap.pgsize,
>> +						range.bitmap.data);
>> +			else
>> +				ret = -EINVAL;
>> +			mutex_unlock(&iommu->lock);
>> +
>> +			return ret;
>> +		}
>>   	}
>>   
>>   	return -ENOTTY;
>> @@ -2345,10 +2568,17 @@ static int vfio_iommu_type1_dma_rw_chunk(struct vfio_iommu *iommu,
>>   
>>   	vaddr = dma->vaddr + offset;
>>   
>> -	if (write)
>> +	if (write) {
>>   		*copied = __copy_to_user((void __user *)vaddr, data,
>>   					 count) ? 0 : count;
>> -	else
>> +		if (*copied && iommu->dirty_page_tracking) {
>> +			unsigned long pgshift =
>> +				__ffs(vfio_pgsize_bitmap(iommu));
>> +
>> +			bitmap_set(dma->bitmap, offset >> pgshift,
>> +				   *copied >> pgshift);
>> +		}
>> +	} else
>>   		*copied = __copy_from_user(data, (void __user *)vaddr,
>>   					   count) ? 0 : count;
>>   	if (kthread)
>