From patchwork Thu Mar 22 04:52:16 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: jason X-Patchwork-Id: 10300867 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 84E8660349 for ; Thu, 22 Mar 2018 04:52:32 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 697A5288EC for ; Thu, 22 Mar 2018 04:52:32 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 59CD6288E6; Thu, 22 Mar 2018 04:52:32 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 58EC229296 for ; Thu, 22 Mar 2018 04:52:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752279AbeCVEw3 (ORCPT ); Thu, 22 Mar 2018 00:52:29 -0400 Received: from out30-132.freemail.mail.aliyun.com ([115.124.30.132]:53584 "EHLO out30-132.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751291AbeCVEw1 (ORCPT ); Thu, 22 Mar 2018 00:52:27 -0400 X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R161e4; CH=green; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01e07487; MF=jason.cai@linux.alibaba.com; NM=1; PH=DS; RN=7; SR=0; TI=SMTPD_---0SztKjhB_1521694336; Received: from localhost(mailfrom:jason.cai@linux.alibaba.com fp:106.11.34.13) by smtp.aliyun-inc.com(127.0.0.1); Thu, 22 Mar 2018 12:52:23 +0800 From: "Jason Cai (Xiang Feng)" To: alex.williamson@redhat.com, pbonzini@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: gnehzuil@linux.alibaba.com, jason.cai@linux.alibaba.com Subject: [PATCH] vfio iommu type1: improve memory pinning process for raw PFN mapping Date: Thu, 22 Mar 2018 12:52:16 +0800 Message-Id: <20180322045216.22220-1-jason.cai@linux.alibaba.com> X-Mailer: git-send-email 2.13.6 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP When using vfio to pass through a PCIe device (e.g. a GPU card) that has a huge BAR (e.g. 16GB), a lot of cycles are wasted on memory pinning because PFNs of PCI BAR are not backed by struct page, and the corresponding VMA has flag VM_PFNMAP. With this change, when pinning a region which is a raw PFN mapping, it can skip unnecessary user memory pinning process, and thus, can significantly improve VM's boot up time when passing through devices via VFIO. In my test on a Xeon E5 2.6GHz, the time mapping a 16GB BAR was reduced from about 0.4s to 1.5us. Signed-off-by: Jason Cai (Xiang Feng) --- drivers/vfio/vfio_iommu_type1.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 45657e2b1ff7..0658f35318b8 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -397,7 +397,6 @@ static long vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr, { unsigned long pfn = 0; long ret, pinned = 0, lock_acct = 0; - bool rsvd; dma_addr_t iova = vaddr - dma->vaddr + dma->iova; /* This code path is only user initiated */ @@ -408,14 +407,22 @@ static long vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr, if (ret) return ret; + if (is_invalid_reserved_pfn(*pfn_base)) { + struct vm_area_struct *vma; + down_read(¤t->mm->mmap_sem); + vma = find_vma_intersection(current->mm, vaddr, vaddr + 1); + pinned = min(npage, (long)vma_pages(vma)); + up_read(¤t->mm->mmap_sem); + return pinned; + } + pinned++; - rsvd = is_invalid_reserved_pfn(*pfn_base); /* * Reserved pages aren't counted against the user, externally pinned * pages are already counted against the user. */ - if (!rsvd && !vfio_find_vpfn(dma, iova)) { + if (!vfio_find_vpfn(dma, iova)) { if (!lock_cap && current->mm->locked_vm + 1 > limit) { put_pfn(*pfn_base, dma->prot); pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n", __func__, @@ -435,13 +442,12 @@ static long vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr, if (ret) break; - if (pfn != *pfn_base + pinned || - rsvd != is_invalid_reserved_pfn(pfn)) { + if (pfn != *pfn_base + pinned) { put_pfn(pfn, dma->prot); break; } - if (!rsvd && !vfio_find_vpfn(dma, iova)) { + if (!vfio_find_vpfn(dma, iova)) { if (!lock_cap && current->mm->locked_vm + lock_acct + 1 > limit) { put_pfn(pfn, dma->prot); @@ -459,10 +465,8 @@ static long vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr, unpin_out: if (ret) { - if (!rsvd) { - for (pfn = *pfn_base ; pinned ; pfn++, pinned--) - put_pfn(pfn, dma->prot); - } + for (pfn = *pfn_base ; pinned ; pfn++, pinned--) + put_pfn(pfn, dma->prot); return ret; }