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=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 4EF06C4332B for ; Fri, 20 Mar 2020 01:00:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0CF4020752 for ; Fri, 20 Mar 2020 01:00:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727257AbgCTBAu (ORCPT ); Thu, 19 Mar 2020 21:00:50 -0400 Received: from mga06.intel.com ([134.134.136.31]:26704 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727235AbgCTBAt (ORCPT ); Thu, 19 Mar 2020 21:00:49 -0400 IronPort-SDR: ajBFmU45SQEEUL8EWGe4UddnL62M6WO7u7tHxi1ntjkEcbXPwN4egFUP88ngt4qgyXrhl+49ha J4Eo0Ts7PXLQ== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Mar 2020 18:00:48 -0700 IronPort-SDR: k5jdLcjTWxc8RnxH9xqj+bTvAbxc0qLU8Pi0MTgzQsf0usvHsAunettib1QPc3OcIYL/mtHXQg i0nJDQVGWPVA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,573,1580803200"; d="scan'208";a="268923613" Received: from joy-optiplex-7040.sh.intel.com (HELO joy-OptiPlex-7040) ([10.239.13.16]) by fmsmga004.fm.intel.com with ESMTP; 19 Mar 2020 18:00:42 -0700 Date: Thu, 19 Mar 2020 20:51:13 -0400 From: Yan Zhao To: Kirti Wankhede Cc: Alex Williamson , "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 v14 Kernel 4/7] vfio iommu: Implementation of ioctl for dirty pages tracking. Message-ID: <20200320005113.GI4641@joy-OptiPlex-7040> Reply-To: Yan Zhao References: <1584560474-19946-1-git-send-email-kwankhede@nvidia.com> <1584560474-19946-5-git-send-email-kwankhede@nvidia.com> <20200319030639.GD4641@joy-OptiPlex-7040> <20200318220100.1aac12fa@w520.home> <20200319041533.GE4641@joy-OptiPlex-7040> <20200318224053.3651c818@w520.home> <20200319061534.GG4641@joy-OptiPlex-7040> <20200319070635.2ff5db56@x1.home> <31621b70-02a9-2ea5-045f-f72b671fe703@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <31621b70-02a9-2ea5-045f-f72b671fe703@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 20, 2020 at 12:57:30AM +0800, Kirti Wankhede wrote: > > > On 3/19/2020 6:36 PM, Alex Williamson wrote: > > On Thu, 19 Mar 2020 02:15:34 -0400 > > Yan Zhao wrote: > > > >> On Thu, Mar 19, 2020 at 12:40:53PM +0800, Alex Williamson wrote: > >>> On Thu, 19 Mar 2020 00:15:33 -0400 > >>> Yan Zhao wrote: > >>> > >>>> On Thu, Mar 19, 2020 at 12:01:00PM +0800, Alex Williamson wrote: > >>>>> On Wed, 18 Mar 2020 23:06:39 -0400 > >>>>> Yan Zhao wrote: > >>>>> > >>>>>> On Thu, Mar 19, 2020 at 03:41:11AM +0800, Kirti Wankhede 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 > >>>>>>> Reviewed-by: Neo Jia > >>>>>>> --- > >>>>>>> drivers/vfio/vfio_iommu_type1.c | 205 +++++++++++++++++++++++++++++++++++++++- > >>>>>>> 1 file changed, 203 insertions(+), 2 deletions(-) > >>>>>>> > >>>>>>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > >>>>>>> index 70aeab921d0f..d6417fb02174 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 +127,10 @@ 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) > >>>>>>> + > >>>>>>> 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 +180,55 @@ 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_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; > >>>>>>> + unsigned long npages = dma->size / pgsize; > >>>>>>> + > >>>>>>> + dma->bitmap = kvzalloc(DIRTY_BITMAP_BYTES(npages), GFP_KERNEL); > >>>>>>> + if (!dma->bitmap) { > >>>>>>> + 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 -ENOMEM; > >>>>>>> + } > >>>>>>> + > >>>>>>> + 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(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; > >>>>>>> + } > >>>>>>> +} > >>>>>>> + > >>>>>>> /* > >>>>>>> * Helper Functions for host iova-pfn list > >>>>>>> */ > >>>>>>> @@ -567,6 +621,14 @@ 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 +863,7 @@ 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 +894,50 @@ 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, > >>>>>>> + unsigned char __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; > >>>>>>> + > >>>>>> looks this size is passed from user. how can it ensure size always > >>>>>> equals to dma->size ? > >>>>>> > >>>>>> shouldn't we iterate dma tree to look for dirty for whole range if a > >>>>>> single dma cannot meet them all? > >>>>> > >>>>> Please see the discussion on v12[1], the problem is with the alignment > >>>>> of DMA mapped regions versus the bitmap. A DMA mapping only requires > >>>>> page alignment, so for example imagine a user requests the bitmap from > >>>>> page zero to 4GB, but we have a DMA mapping starting at 4KB. We can't > >>>>> efficiently copy the bitmap tracked by the vfio_dma structure to the > >>>>> user buffer when it's shifted by 1 bit. Adjacent mappings can also > >>>>> make for a very complicated implementation. In the discussion linked > >>>>> we decided to compromise on a more simple implementation that requires > >>>>> the user to ask for a bitmap which exactly matches a single DMA > >>>>> mapping, which Kirti indicates is what we require to support QEMU. > >>>>> Later in the series, the unmap operation also makes this requirement > >>>>> when used with the flags to retrieve the dirty bitmap. Thanks, > >>>>> > >>>> > >>>> so, what about for vIOMMU enabling case? > >>>> if IOVAs are mapped per page, then there's a log_sync in qemu, > >>>> it's supposed for range from 0-U64MAX, qemu has to find out which > >>>> ones are mapped and cut them into pages before calling this IOCTL? > >>>> And what if those IOVAs are mapped for len more than one page? > >>> > >>> Good question. Kirti? > >>> > > In log_sync with vIOMMU, loop for range such that: > > - find iotlb entry for iova, get iova_xlat > - size = iotlb.addr_mask + 1; This is same caculation as when mapping > are created from vfio_iommu_map_notify() > - use the for VFIO_IOMMU_DIRTY_PAGES ioctl > - increment iova: iova += size > - iterate above steps till end of range. > Ok. It makes sense, though not efficient :) think about when there's no iotlb found for an iova, page by page incremental of iova is required. right? > >>>>> [1] https://lore.kernel.org/kvm/20200218215330.5bc8fc6a@w520.home/ > >>>>> > >>>>>>> + 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; > >>>>>>> + > >> Here, dma->bitmap needs to be cleared. right? > > > > Ah, I missed re-checking this in my review. v13 did clear it, but I > > noted that we need to re-populate any currently pinned pages. This > > neither clears nor repopulates. That's wrong. Thanks, > > > > 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 > > > Alex > > > >>>>>>> + return 0; > >>>>>>> +} > >>>>>>> + > >>>>>>> +static int verify_bitmap_size(uint64_t npages, uint64_t bitmap_size) > >>>>>>> +{ > >>>>>>> + uint64_t bsize; > >>>>>>> + > >>>>>>> + if (!npages || !bitmap_size || bitmap_size > UINT_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) > >>>>>>> { > >>>>>>> @@ -2278,6 +2385,93 @@ 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(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(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, > >>>>>>> + (unsigned char __user *)range.bitmap.data); > >>>>>>> + else > >>>>>>> + ret = -EINVAL; > >>>>>>> + mutex_unlock(&iommu->lock); > >>>>>>> + > >>>>>>> + return ret; > >>>>>>> + } > >>>>>>> } > >>>>>>> > >>>>>>> return -ENOTTY; > >>>>>>> @@ -2345,10 +2539,17 @@ 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) > >>>>>>> -- > >>>>>>> 2.7.0 > >>>>>>> > >>>>>> > >>>>> > >>>> > >>> > >> > >