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=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,URIBL_BLOCKED, 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 90C80C43331 for ; Fri, 27 Mar 2020 14:10:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4EA96206F2 for ; Fri, 27 Mar 2020 14:10:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="XqJvpbd4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726770AbgC0OKO (ORCPT ); Fri, 27 Mar 2020 10:10:14 -0400 Received: from us-smtp-delivery-74.mimecast.com ([63.128.21.74]:48992 "EHLO us-smtp-delivery-74.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726333AbgC0OKO (ORCPT ); Fri, 27 Mar 2020 10:10:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585318212; 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: in-reply-to:in-reply-to:references:references; bh=SeSmYpkonMXFn0lSb7uFQTaAY1L7CG3um1mEI2E+uM4=; b=XqJvpbd4Qq9W24kvIWbeQOMmn2b10bOvgXOJWJ4U7VLlse0E9ClhhfZq5BueiJFYKkYXAN V0MMDdw9JYIY4wesbYzXS/Zwd6EfKcL2Mq4GsprKUZtqZXy6dPKbJsKRaFPyovj3yi0Mfs KJDc6DjfCAFQL+K0X3iPaubfCf2yn28= 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-360-jPI-FJHjOnSw7jHJVLrYFg-1; Fri, 27 Mar 2020 10:10:09 -0400 X-MC-Unique: jPI-FJHjOnSw7jHJVLrYFg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5A5CE801A03; Fri, 27 Mar 2020 14:10:01 +0000 (UTC) Received: from work-vm (ovpn-113-149.ams2.redhat.com [10.36.113.149]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3BF10953CC; Fri, 27 Mar 2020 14:09:42 +0000 (UTC) Date: Fri, 27 Mar 2020 14:09:39 +0000 From: "Dr. David Alan Gilbert" To: Alex Williamson Cc: Kirti Wankhede , cjia@nvidia.com, kevin.tian@intel.com, ziye.yang@intel.com, changpeng.liu@intel.com, yi.l.liu@intel.com, mlevitsk@redhat.com, eskultet@redhat.com, cohuck@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, zhi.a.wang@intel.com, yan.y.zhao@intel.com, qemu-devel@nongnu.org, kvm@vger.kernel.org Subject: Re: [PATCH v16 Kernel 4/7] vfio iommu: Implementation of ioctl for dirty pages tracking. Message-ID: <20200327140939.GI2786@work-vm> References: <1585084732-18473-1-git-send-email-kwankhede@nvidia.com> <20200327115745.GF2786@work-vm> <20200327075755.5052f470@x1.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200327075755.5052f470@x1.home> User-Agent: Mutt/1.13.3 (2020-01-12) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org * Alex Williamson (alex.williamson@redhat.com) wrote: > On Fri, 27 Mar 2020 11:57:45 +0000 > "Dr. David Alan Gilbert" wrote: > > > * 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 > > > Reviewed-by: Neo Jia > > > --- > > > drivers/vfio/vfio_iommu_type1.c | 266 +++++++++++++++++++++++++++++++++++++++- > > > 1 file changed, 260 insertions(+), 6 deletions(-) > > > > > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > > > index 70aeab921d0f..874a1a7ae925 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. > > > + */ > > > > Can you explain to me what that size is the limit of? People are > > already running 12TB VMs. > > It's the limit of a single DMA mapping range. KVM has the same > limitation for memory slots. People are running large VMs, but they > need to use hotpluggable DIMMs or NUMA configuration such that any > single KVM memory slot is less than 8TB. The same should be sufficient > here. Thanks, Ah OK, that's fine. Dave > Alex > > > > +#define DIRTY_BITMAP_PAGES_MAX (uint64_t)(INT_MAX - 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 +191,77 @@ 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; > > > + > > > + if (npages > DIRTY_BITMAP_PAGES_MAX) > > > + return -EINVAL; > > > + > > > + dma->bitmap = kvzalloc(DIRTY_BITMAP_BYTES(npages), GFP_KERNEL); > > > + if (!dma->bitmap) > > > + return -ENOMEM; > > > + > > > + return 0; > > > +} > > > + > > > +static void vfio_dma_bitmap_free(struct vfio_dma *dma) > > > +{ > > > + kfree(dma->bitmap); > > > + dma->bitmap = NULL; > > > +} > > > + > > > +static void vfio_dma_populate_bitmap(struct vfio_dma *dma, uint64_t pgsize) > > > +{ > > > + struct rb_node *p; > > > + > > > + if (RB_EMPTY_ROOT(&dma->pfn_list)) > > > + return; > > > + > > > + 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); > > > + } > > > +} > > > + > > > +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); > > > + 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); > > > + > > > + vfio_dma_bitmap_free(dma); > > > + } > > > + return ret; > > > + } > > > + vfio_dma_populate_bitmap(dma, pgsize); > > > + } > > > + 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); > > > + > > > + vfio_dma_bitmap_free(dma); > > > + } > > > +} > > > + > > > /* > > > * Helper Functions for host iova-pfn list > > > */ > > > @@ -567,6 +654,18 @@ 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 populated with the smallest supported page > > > + * size > > > + */ > > > + bitmap_set(dma->bitmap, > > > + (vpfn->iova - dma->iova) >> pgshift, 1); > > > + } > > > } > > > > > > ret = i; > > > @@ -801,6 +900,7 @@ 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); > > > + vfio_dma_bitmap_free(dma); > > > kfree(dma); > > > iommu->dma_avail++; > > > } > > > @@ -831,6 +931,57 @@ 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; > > > + > > > + /* > > > + * Re-populate bitmap to include all pinned pages which are considered > > > + * as dirty but exclude pages which are unpinned and pages which are > > > + * marked dirty by vfio_dma_rw() > > > + */ > > > + bitmap_clear(dma->bitmap, 0, npages); > > > + vfio_dma_populate_bitmap(dma, pgsize); > > > + 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 +1189,16 @@ 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 +1206,7 @@ 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 +1281,12 @@ 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 +2435,93 @@ 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 smallest 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 +2589,20 @@ 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 populated with the smallest supported page > > > + * size > > > + */ > > > + 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 > > > > > -- > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK