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=-6.6 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 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 D5569C4332B for ; Thu, 19 Mar 2020 13:07:32 +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 911D72078C for ; Thu, 19 Mar 2020 13:07:32 +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="PuQLY4C2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 911D72078C 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]:37658 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jEutX-0006xn-No for qemu-devel@archiver.kernel.org; Thu, 19 Mar 2020 09:07:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60324) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jEust-0006Wv-Qd for qemu-devel@nongnu.org; Thu, 19 Mar 2020 09:06:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jEusp-0007Ny-UR for qemu-devel@nongnu.org; Thu, 19 Mar 2020 09:06:51 -0400 Received: from us-smtp-delivery-74.mimecast.com ([216.205.24.74]:26510) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jEusp-0007No-P9 for qemu-devel@nongnu.org; Thu, 19 Mar 2020 09:06:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1584623207; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=fUztR+WBoceUNZRhQxT8A2gL9yX/ZO7lA2PeqWLfSsg=; b=PuQLY4C25k2erwR5j2189ItV0rgHRPdUSuT8vbCLxs5sgGa3Ikhr/89JQeLpbov7/ukta3 VpUrNb+sdJyaw2nVc6XA8oOjodUJA7vp3KjTVOhNg20REwbkYuW6HEeTy7FRXMauUyQzVB v3etS6Zt6S76TVpYh60bqXLCLTfiVkg= 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-329-t39YGnHUO-qyoWYvldVA7w-1; Thu, 19 Mar 2020 09:06:40 -0400 X-MC-Unique: t39YGnHUO-qyoWYvldVA7w-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id F1F068010F2; Thu, 19 Mar 2020 13:06:37 +0000 (UTC) Received: from x1.home (ovpn-112-162.phx2.redhat.com [10.3.112.162]) by smtp.corp.redhat.com (Postfix) with ESMTP id 15D615C241; Thu, 19 Mar 2020 13:06:36 +0000 (UTC) Date: Thu, 19 Mar 2020 07:06:35 -0600 From: Alex Williamson To: Yan Zhao Subject: Re: [PATCH v14 Kernel 4/7] vfio iommu: Implementation of ioctl for dirty pages tracking. Message-ID: <20200319070635.2ff5db56@x1.home> In-Reply-To: <20200319061534.GG4641@joy-OptiPlex-7040> 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> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 216.205.24.74 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" , "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" , Kirti Wankhede , "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 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? > > > > > > [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, 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 > > > > > > > > > > > > > > > > > > > > >