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Thu, 26 Mar 2020 14:39:20 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Thu, 26 Mar 2020 14:40:06 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Thu, 26 Mar 2020 14:40:06 -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; Thu, 26 Mar 2020 21:39:49 +0000 Subject: Re: [PATCH v16 Kernel 5/7] vfio iommu: Update UNMAP_DMA ioctl to get dirty bitmap before unmap 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> X-Nvconfidentiality: public From: Kirti Wankhede Message-ID: <3cabb357-b9c5-f8b3-5d57-1178ec0dde5a@nvidia.com> Date: Fri, 27 Mar 2020 03:09:44 +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: <20200325021800.GC20109@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=1585258760; bh=bCv8xFt67Ype0cXdZilDfCCaBvXkLNGrD7lATqJeSx8=; 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=hjNSb8P22yDn3ELLPwuMVm3Jk6sIlC9546/4bKQJghCPUozI67kcGkx7rPkec6BcK hBcBc46u1Vy7kOcJzY7GaZV8SVvLOR+HSX92fJkLLbCkLYtOOBt8duarTT9w0Yd3P2 j4pbf7HVs/shlq+V+buL0BhzE/RlsmJ2wgTULjZjU3N6OJ5wFgajGW/9TNMr9VR7qR OftW4oH/EHynpXW0LDYLSdt+HToDgcU9/SlUszi5dvB/oM1vnQTbKYwZrSnrHNNwyp p9eWQRvUmxTsVVN61tqzEGDcyYnFU0SJ77feeSqLhAN2L4g4QnkZ/1Rurxphi3TVps b8XHa00GWqx/Q== X-detected-operating-system: by eggs.gnu.org: Windows 7 or 8 [fuzzy] X-Received-From: 216.228.121.64 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Zhengxiao.zx@Alibaba-inc.com" , "Tian, Kevin" , "Liu, Yi L" , "cjia@nvidia.com" , "kvm@vger.kernel.org" , "eskultet@redhat.com" , "Yang, Ziye" , "qemu-devel@nongnu.org" , "cohuck@redhat.com" , "shuangtai.tst@alibaba-inc.com" , "dgilbert@redhat.com" , "Wang, Zhi A" , "mlevitsk@redhat.com" , "pasic@linux.ibm.com" , "aik@ozlabs.ru" , "alex.williamson@redhat.com" , "eauger@redhat.com" , "felipe@nutanix.com" , "jonathan.davies@nutanix.com" , "Liu, Changpeng" , "Ken.Xue@amd.com" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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? >>> >>> 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 Hope that helps. Thanks, Kirti