From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756189AbcLSWOD (ORCPT ); Mon, 19 Dec 2016 17:14:03 -0500 Received: from mx1.redhat.com ([209.132.183.28]:48770 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754424AbcLSWN6 (ORCPT ); Mon, 19 Dec 2016 17:13:58 -0500 Subject: [PATCH v2] vfio/type1: Restore mapping performance with mdev support From: Alex Williamson To: alex.williamson@redhat.com Cc: kwankhede@nvidia.com, cjia@nvidia.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Date: Mon, 19 Dec 2016 15:13:57 -0700 Message-ID: <20161219221046.4719.17454.stgit@gimli.home> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Mon, 19 Dec 2016 22:13:58 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As part of the mdev support, type1 now gets a task reference per vfio_dma and uses that to get an mm reference for the task while working on accounting. That's correct, but it's not fast. For some paths, like vfio_pin_pages_remote(), we know we're only called from user context, so we can restore the lighter weight calls. In other cases, we're effectively already testing whether we're in the stored task context elsewhere, extend this vfio_lock_acct() as well. Signed-off-by: Alex Williamson --- v2: Use (mm == current->mm) test in vfio_lock_acct() as well rather than passing around is_current. It doesn't make sense to keep it in vaddr_get_pfn() and not use it elsewhere. drivers/vfio/vfio_iommu_type1.c | 98 ++++++++++++++++++++------------------- 1 file changed, 51 insertions(+), 47 deletions(-) diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 9815e45..7154987 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -268,28 +268,38 @@ static void vfio_lock_acct(struct task_struct *task, long npage) { struct vwork *vwork; struct mm_struct *mm; + bool is_current; if (!npage) return; - mm = get_task_mm(task); + is_current = (task->mm == current->mm); + + mm = is_current ? task->mm : get_task_mm(task); if (!mm) - return; /* process exited or nothing to do */ + return; /* process exited */ if (down_write_trylock(&mm->mmap_sem)) { mm->locked_vm += npage; up_write(&mm->mmap_sem); - mmput(mm); + if (!is_current) + mmput(mm); return; } + if (is_current) { + mm = get_task_mm(task); + if (!mm) + return; + } + /* * Couldn't get mmap_sem lock, so must setup to update * mm->locked_vm later. If locked_vm were atomic, we * wouldn't need this silliness */ vwork = kmalloc(sizeof(struct vwork), GFP_KERNEL); - if (!vwork) { + if (WARN_ON(!vwork)) { mmput(mm); return; } @@ -393,77 +403,71 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr, static long vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr, long npage, unsigned long *pfn_base) { - unsigned long limit; - bool lock_cap = ns_capable(task_active_pid_ns(dma->task)->user_ns, - CAP_IPC_LOCK); - struct mm_struct *mm; - long ret, i = 0, lock_acct = 0; + unsigned long limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; + bool lock_cap = capable(CAP_IPC_LOCK); + long ret, pinned = 0, lock_acct = 0; bool rsvd; dma_addr_t iova = vaddr - dma->vaddr + dma->iova; - mm = get_task_mm(dma->task); - if (!mm) + /* This code path is only user initiated */ + if (!current->mm) return -ENODEV; - ret = vaddr_get_pfn(mm, vaddr, dma->prot, pfn_base); + ret = vaddr_get_pfn(current->mm, vaddr, dma->prot, pfn_base); if (ret) - goto pin_pg_remote_exit; + return ret; + pinned++; rsvd = is_invalid_reserved_pfn(*pfn_base); - limit = task_rlimit(dma->task, RLIMIT_MEMLOCK) >> PAGE_SHIFT; /* * 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 (!lock_cap && mm->locked_vm + 1 > limit) { + if (!lock_cap && current->mm->locked_vm + 1 > limit) { put_pfn(*pfn_base, dma->prot); pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n", __func__, limit << PAGE_SHIFT); - ret = -ENOMEM; - goto pin_pg_remote_exit; + return -ENOMEM; } lock_acct++; } - i++; - if (likely(!disable_hugepages)) { - /* Lock all the consecutive pages from pfn_base */ - for (vaddr += PAGE_SIZE, iova += PAGE_SIZE; i < npage; - i++, vaddr += PAGE_SIZE, iova += PAGE_SIZE) { - unsigned long pfn = 0; + if (unlikely(disable_hugepages)) + goto out; - ret = vaddr_get_pfn(mm, vaddr, dma->prot, &pfn); - if (ret) - break; + /* Lock all the consecutive pages from pfn_base */ + for (vaddr += PAGE_SIZE, iova += PAGE_SIZE; pinned < npage; + pinned++, vaddr += PAGE_SIZE, iova += PAGE_SIZE) { + unsigned long pfn = 0; - if (pfn != *pfn_base + i || - rsvd != is_invalid_reserved_pfn(pfn)) { + ret = vaddr_get_pfn(current->mm, vaddr, dma->prot, &pfn); + if (ret) + break; + + if (pfn != *pfn_base + pinned || + rsvd != is_invalid_reserved_pfn(pfn)) { + put_pfn(pfn, dma->prot); + break; + } + + if (!rsvd && !vfio_find_vpfn(dma, iova)) { + if (!lock_cap && + current->mm->locked_vm + lock_acct + 1 > limit) { put_pfn(pfn, dma->prot); + pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n", + __func__, limit << PAGE_SHIFT); break; } - - if (!rsvd && !vfio_find_vpfn(dma, iova)) { - if (!lock_cap && - mm->locked_vm + lock_acct + 1 > limit) { - put_pfn(pfn, dma->prot); - pr_warn("%s: RLIMIT_MEMLOCK (%ld) " - "exceeded\n", __func__, - limit << PAGE_SHIFT); - break; - } - lock_acct++; - } + lock_acct++; } } - vfio_lock_acct(dma->task, lock_acct); - ret = i; +out: + vfio_lock_acct(current, lock_acct); -pin_pg_remote_exit: - mmput(mm); - return ret; + return pinned; } static long vfio_unpin_pages_remote(struct vfio_dma *dma, dma_addr_t iova, @@ -473,10 +477,10 @@ static long vfio_unpin_pages_remote(struct vfio_dma *dma, dma_addr_t iova, long unlocked = 0, locked = 0; long i; - for (i = 0; i < npage; i++) { + for (i = 0; i < npage; i++, iova += PAGE_SIZE) { if (put_pfn(pfn++, dma->prot)) { unlocked++; - if (vfio_find_vpfn(dma, iova + (i << PAGE_SHIFT))) + if (vfio_find_vpfn(dma, iova)) locked++; } }