From patchwork Tue Aug 7 09:51:05 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiao Guangrong X-Patchwork-Id: 1284771 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork2.kernel.org (Postfix) with ESMTP id E3B99DF280 for ; Tue, 7 Aug 2012 09:52:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753719Ab2HGJvh (ORCPT ); Tue, 7 Aug 2012 05:51:37 -0400 Received: from e28smtp08.in.ibm.com ([122.248.162.8]:59077 "EHLO e28smtp08.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751742Ab2HGJvg (ORCPT ); Tue, 7 Aug 2012 05:51:36 -0400 Received: from /spool/local by e28smtp08.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Tue, 7 Aug 2012 15:21:08 +0530 Received: from d28av03.in.ibm.com (d28av03.in.ibm.com [9.184.220.65]) by d28relay03.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q779p75R22675598; Tue, 7 Aug 2012 15:21:07 +0530 Received: from d28av03.in.ibm.com (loopback [127.0.0.1]) by d28av03.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q779p7sh011864; Tue, 7 Aug 2012 19:51:07 +1000 Received: from localhost.localdomain ([9.123.236.99]) by d28av03.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id q779p5em011742; Tue, 7 Aug 2012 19:51:06 +1000 Message-ID: <5020E509.8070901@linux.vnet.ibm.com> Date: Tue, 07 Aug 2012 17:51:05 +0800 From: Xiao Guangrong User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120717 Thunderbird/14.0 MIME-Version: 1.0 To: Xiao Guangrong CC: Avi Kivity , Marcelo Tosatti , LKML , KVM Subject: [PATCH v5 05/12] KVM: reorganize hva_to_pfn References: <5020E423.9080004@linux.vnet.ibm.com> In-Reply-To: <5020E423.9080004@linux.vnet.ibm.com> x-cbid: 12080709-2000-0000-0000-000008A059E3 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org We do too many things in hva_to_pfn, this patch reorganize the code, let it be better readable Signed-off-by: Xiao Guangrong --- virt/kvm/kvm_main.c | 159 +++++++++++++++++++++++++++++++-------------------- 1 files changed, 97 insertions(+), 62 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 26ffc87..dd01bcb 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1043,83 +1043,118 @@ static inline int check_user_page_hwpoison(unsigned long addr) return rc == -EHWPOISON; } -static pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, - bool write_fault, bool *writable) +/* + * The atomic path to get the writable pfn which will be stored in @pfn, + * true indicates success, otherwise false is returned. + */ +static bool hva_to_pfn_fast(unsigned long addr, bool atomic, bool *async, + bool write_fault, bool *writable, pfn_t *pfn) { struct page *page[1]; - int npages = 0; - pfn_t pfn; + int npages; - /* we can do it either atomically or asynchronously, not both */ - BUG_ON(atomic && async); + if (!(async || atomic)) + return false; - BUG_ON(!write_fault && !writable); + npages = __get_user_pages_fast(addr, 1, 1, page); + if (npages == 1) { + *pfn = page_to_pfn(page[0]); - if (writable) - *writable = true; + if (writable) + *writable = true; + return true; + } + + return false; +} - if (atomic || async) - npages = __get_user_pages_fast(addr, 1, 1, page); +/* + * The slow path to get the pfn of the specified host virtual address, + * 1 indicates success, -errno is returned if error is detected. + */ +static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault, + bool *writable, pfn_t *pfn) +{ + struct page *page[1]; + int npages = 0; - if (unlikely(npages != 1) && !atomic) { - might_sleep(); + might_sleep(); - if (writable) - *writable = write_fault; - - if (async) { - down_read(¤t->mm->mmap_sem); - npages = get_user_page_nowait(current, current->mm, - addr, write_fault, page); - up_read(¤t->mm->mmap_sem); - } else - npages = get_user_pages_fast(addr, 1, write_fault, - page); - - /* map read fault as writable if possible */ - if (unlikely(!write_fault) && npages == 1) { - struct page *wpage[1]; - - npages = __get_user_pages_fast(addr, 1, 1, wpage); - if (npages == 1) { - *writable = true; - put_page(page[0]); - page[0] = wpage[0]; - } - npages = 1; + if (writable) + *writable = write_fault; + + if (async) { + down_read(¤t->mm->mmap_sem); + npages = get_user_page_nowait(current, current->mm, + addr, write_fault, page); + up_read(¤t->mm->mmap_sem); + } else + npages = get_user_pages_fast(addr, 1, write_fault, + page); + if (npages != 1) + return npages; + + /* map read fault as writable if possible */ + if (unlikely(!write_fault)) { + struct page *wpage[1]; + + npages = __get_user_pages_fast(addr, 1, 1, wpage); + if (npages == 1) { + *writable = true; + put_page(page[0]); + page[0] = wpage[0]; } + + npages = 1; } + *pfn = page_to_pfn(page[0]); + return npages; +} + +static pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, + bool write_fault, bool *writable) +{ + struct vm_area_struct *vma; + pfn_t pfn = 0; + int npages; - if (unlikely(npages != 1)) { - struct vm_area_struct *vma; + /* we can do it either atomically or asynchronously, not both */ + BUG_ON(atomic && async); - if (atomic) - return KVM_PFN_ERR_FAULT; + BUG_ON(!write_fault && !writable); - down_read(¤t->mm->mmap_sem); - if (npages == -EHWPOISON || - (!async && check_user_page_hwpoison(addr))) { - up_read(¤t->mm->mmap_sem); - return KVM_PFN_ERR_HWPOISON; - } + if (hva_to_pfn_fast(addr, atomic, async, write_fault, writable, &pfn)) + return pfn; - vma = find_vma_intersection(current->mm, addr, addr+1); - - if (vma == NULL) - pfn = KVM_PFN_ERR_FAULT; - else if ((vma->vm_flags & VM_PFNMAP)) { - pfn = ((addr - vma->vm_start) >> PAGE_SHIFT) + - vma->vm_pgoff; - BUG_ON(!kvm_is_mmio_pfn(pfn)); - } else { - if (async && (vma->vm_flags & VM_WRITE)) - *async = true; - pfn = KVM_PFN_ERR_FAULT; - } - up_read(¤t->mm->mmap_sem); - } else - pfn = page_to_pfn(page[0]); + if (atomic) + return KVM_PFN_ERR_FAULT; + npages = hva_to_pfn_slow(addr, async, write_fault, writable, &pfn); + if (npages == 1) + return pfn; + + down_read(¤t->mm->mmap_sem); + if (npages == -EHWPOISON || + (!async && check_user_page_hwpoison(addr))) { + pfn = KVM_PFN_ERR_HWPOISON; + goto exit; + } + + vma = find_vma_intersection(current->mm, addr, addr + 1); + + if (vma == NULL) + pfn = KVM_PFN_ERR_FAULT; + else if ((vma->vm_flags & VM_PFNMAP)) { + pfn = ((addr - vma->vm_start) >> PAGE_SHIFT) + + vma->vm_pgoff; + BUG_ON(!kvm_is_mmio_pfn(pfn)); + } else { + if (async && (vma->vm_flags & VM_WRITE)) + *async = true; + pfn = KVM_PFN_ERR_FAULT; + } +exit: + up_read(¤t->mm->mmap_sem); return pfn; }