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=-6.9 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 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 89DDCC43331 for ; Tue, 24 Mar 2020 20:45:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5696F205ED for ; Tue, 24 Mar 2020 20:45:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="J5lq17o1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728107AbgCXUpa (ORCPT ); Tue, 24 Mar 2020 16:45:30 -0400 Received: from us-smtp-delivery-74.mimecast.com ([216.205.24.74]:34225 "EHLO us-smtp-delivery-74.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727969AbgCXUp3 (ORCPT ); Tue, 24 Mar 2020 16:45:29 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585082726; 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=QkUK7ALJQH7LmlBExejAFxKUpSojd9B3auWcg0AJiHE=; b=J5lq17o1X7FqDFTTs2jL3eSTLdSQg268dvoyL+TqmJFL7E0O0MEcJAvkp+psgU3yyVMu2U JkRi85oy/8K47KMdl5KnBFTPg0ftX06NugByH+Qj5JRkQBpPq/b1AwM/bBiDDAl5HZEt6z ywdM2RXwcqkVDUvYrGqYEqv1KlW3WGM= 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-395-XYhadAsHMFiGs7CQQh7OMw-1; Tue, 24 Mar 2020 16:45:22 -0400 X-MC-Unique: XYhadAsHMFiGs7CQQh7OMw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 04204A1361; Tue, 24 Mar 2020 20:45:17 +0000 (UTC) Received: from w520.home (ovpn-112-162.phx2.redhat.com [10.3.112.162]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9274F5DA87; Tue, 24 Mar 2020 20:45:07 +0000 (UTC) Date: Tue, 24 Mar 2020 14:45:07 -0600 From: Alex Williamson To: Kirti Wankhede Cc: , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v16 Kernel 4/7] vfio iommu: Implementation of ioctl for dirty pages tracking. Message-ID: <20200324144507.5e11a50d@w520.home> In-Reply-To: <20200324143716.64cf0cc9@w520.home> References: <1585078359-20124-1-git-send-email-kwankhede@nvidia.com> <1585078359-20124-5-git-send-email-kwankhede@nvidia.com> <20200324143716.64cf0cc9@w520.home> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, 24 Mar 2020 14:37:16 -0600 Alex Williamson wrote: > On Wed, 25 Mar 2020 01:02:36 +0530 > 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 | 265 +++++++++++++++++++++++++++++++++++++++- > > 1 file changed, 259 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > > index 70aeab921d0f..27ed069c5053 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. > > + */ > > +#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 +931,56 @@ 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() > > + */ > > + vfio_dma_populate_bitmap(dma, pgsize); > > vfio_dma_populate_bitmap() only sets bits, it doesn't clear them. > Shouldn't we do a memset() zero before calling this? Thanks, Or a bitmap_clear() would be better given we use bitmap_set() above. Thanks, Alex