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=-8.0 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,URIBL_BLOCKED,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 31DC6C43331 for ; Fri, 27 Mar 2020 11:58:50 +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 DC74220787 for ; Fri, 27 Mar 2020 11:58:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Exuw/bTx" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DC74220787 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:40716 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jHndR-0000Rc-3g for qemu-devel@archiver.kernel.org; Fri, 27 Mar 2020 07:58:49 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52801) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jHnco-0008Pc-Hm for qemu-devel@nongnu.org; Fri, 27 Mar 2020 07:58:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jHncl-0001wK-0R for qemu-devel@nongnu.org; Fri, 27 Mar 2020 07:58:09 -0400 Received: from us-smtp-delivery-74.mimecast.com ([63.128.21.74]:37265) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jHnck-0001o5-OM for qemu-devel@nongnu.org; Fri, 27 Mar 2020 07:58:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585310285; 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=UiIyjrky4Ux3DZQVAUuU0mcMA01ki2x9mIo9Skykjig=; b=Exuw/bTxezocnx0NwauDJeEb0nqXEmwXQir0SXy2idBp98lRj8jRol1tySNCLo0/I0Dyq2 JaiFb/cT6hJcNZN8pqDo3Gj2rP3I7npm6v29pVp/RoKSqolxMeh8kwASJBlSZwV3NHbwxg NhrhmmJkCC5RG/Z2betsQFWydJaTYYc= 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-172-GH6Vu_FLPD6k3wqVGy1Z0A-1; Fri, 27 Mar 2020 07:58:02 -0400 X-MC-Unique: GH6Vu_FLPD6k3wqVGy1Z0A-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EFDF2801E53; Fri, 27 Mar 2020 11:57:57 +0000 (UTC) Received: from work-vm (ovpn-113-109.ams2.redhat.com [10.36.113.109]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2B43CCDBD2; Fri, 27 Mar 2020 11:57:47 +0000 (UTC) Date: Fri, 27 Mar 2020 11:57:45 +0000 From: "Dr. David Alan Gilbert" To: Kirti Wankhede Subject: Re: [PATCH v16 Kernel 4/7] vfio iommu: Implementation of ioctl for dirty pages tracking. Message-ID: <20200327115745.GF2786@work-vm> References: <1585084732-18473-1-git-send-email-kwankhede@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1585084732-18473-1-git-send-email-kwankhede@nvidia.com> User-Agent: Mutt/1.13.3 (2020-01-12) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 63.128.21.74 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, kevin.tian@intel.com, yi.l.liu@intel.com, cjia@nvidia.com, kvm@vger.kernel.org, eskultet@redhat.com, ziye.yang@intel.com, cohuck@redhat.com, shuangtai.tst@alibaba-inc.com, qemu-devel@nongnu.org, zhi.a.wang@intel.com, mlevitsk@redhat.com, pasic@linux.ibm.com, aik@ozlabs.ru, alex.williamson@redhat.com, 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" * 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. Dave > +#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