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 24BF5C4332D for ; Thu, 19 Mar 2020 06:25:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E4E0E20714 for ; Thu, 19 Mar 2020 06:25:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727060AbgCSGZJ (ORCPT ); Thu, 19 Mar 2020 02:25:09 -0400 Received: from mga04.intel.com ([192.55.52.120]:63744 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725767AbgCSGZI (ORCPT ); Thu, 19 Mar 2020 02:25:08 -0400 IronPort-SDR: TfVsTepOiTLwtU2BGkvqSZxC2LkWvFe4gsP3M9bxr6rRsAz/qRqgOC21pKLBdWQdOex7IbaAAm em8/GMqtxzLw== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Mar 2020 23:25:08 -0700 IronPort-SDR: CrZSm3d6V4c6ikoZn5JxlUIsQmixrctWXVim5vheZiA3pzbuvbxNCCyvdbFT1RDrnR0x1IzlwN w8ejzN0lQ/Ew== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,570,1574150400"; d="scan'208";a="444452018" Received: from joy-optiplex-7040.sh.intel.com (HELO joy-OptiPlex-7040) ([10.239.13.16]) by fmsmga005.fm.intel.com with ESMTP; 18 Mar 2020 23:25:03 -0700 Date: Thu, 19 Mar 2020 02:15:34 -0400 From: Yan Zhao To: Alex Williamson Cc: Kirti Wankhede , "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: <20200319061534.GG4641@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200318224053.3651c818@w520.home> 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 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? > > > > [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? > > > > > + 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 > > > > > > > > > > > > > > >