Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758615AbcC3Hju (ORCPT ); Wed, 30 Mar 2016 03:39:50 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:56468 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751547AbcC3Hjs (ORCPT ); Wed, 30 Mar 2016 03:39:48 -0400 Message-ID: <56FB8258.7030303@huawei.com> Date: Wed, 30 Mar 2016 15:38:00 +0800 From: Shannon Zhao User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Julien Grall , Shannon Zhao , , , CC: , , , , , , Subject: Re: [PATCH v7 03/17] Xen: xlate: Use page_to_xen_pfn instead of page_to_pfn References: <1458830676-27075-1-git-send-email-shannon.zhao@linaro.org> <1458830676-27075-4-git-send-email-shannon.zhao@linaro.org> <56FAAD48.2010401@arm.com> In-Reply-To: <56FAAD48.2010401@arm.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.16.142] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A090202.56FB826F.009D,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-06-18 04:22:30, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 9629cc708389ef29d54aa479b869bc45 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2448 Lines: 68 On 2016/3/30 0:28, Julien Grall wrote: > Hi Shannon, > > On 24/03/16 14:44, Shannon Zhao wrote: >> Make xen_xlate_map_ballooned_pages work with 64K pages. In that case >> Kernel pages are 64K in size but Xen pages remain 4K in size. Xen pfns >> refer to 4K pages. >> >> Signed-off-by: Shannon Zhao >> Reviewed-by: Stefano Stabellini >> --- >> drivers/xen/xlate_mmu.c | 26 ++++++++++++++++---------- >> 1 file changed, 16 insertions(+), 10 deletions(-) >> >> diff --git a/drivers/xen/xlate_mmu.c b/drivers/xen/xlate_mmu.c >> index 9692656..28f728b 100644 >> --- a/drivers/xen/xlate_mmu.c >> +++ b/drivers/xen/xlate_mmu.c >> @@ -207,9 +207,12 @@ int __init >> xen_xlate_map_ballooned_pages(xen_pfn_t **gfns, void **virt, >> void *vaddr; >> int rc; >> unsigned int i; >> + unsigned long nr_pages; >> + xen_pfn_t xen_pfn = 0; >> >> BUG_ON(nr_grant_frames == 0); >> - pages = kcalloc(nr_grant_frames, sizeof(pages[0]), GFP_KERNEL); >> + nr_pages = DIV_ROUND_UP(nr_grant_frames, XEN_PFN_PER_PAGE); >> + pages = kcalloc(nr_pages, sizeof(pages[0]), GFP_KERNEL); >> if (!pages) >> return -ENOMEM; >> >> @@ -218,22 +221,25 @@ int __init >> xen_xlate_map_ballooned_pages(xen_pfn_t **gfns, void **virt, >> kfree(pages); >> return -ENOMEM; >> } >> - rc = alloc_xenballooned_pages(nr_grant_frames, pages); >> + rc = alloc_xenballooned_pages(nr_pages, pages); >> if (rc) { >> - pr_warn("%s Couldn't balloon alloc %ld pfns rc:%d\n", __func__, >> - nr_grant_frames, rc); >> + pr_warn("%s Couldn't balloon alloc %ld pages rc:%d\n", __func__, >> + nr_pages, rc); >> kfree(pages); >> kfree(pfns); >> return rc; >> } >> - for (i = 0; i < nr_grant_frames; i++) >> - pfns[i] = page_to_pfn(pages[i]); >> + for (i = 0; i < nr_grant_frames; i++) { >> + if ((i % XEN_PFN_PER_PAGE) == 0) >> + xen_pfn = page_to_xen_pfn(pages[i / XEN_PFN_PER_PAGE]); >> + pfns[i] = pfn_to_gfn(xen_pfn++); >> + } > > Would it be possible to re-use xen_for_each_gfn? This will avoid > open-coding the loop to break down the Linux page. I don't think so. Using xen_acpi_guest_init will require factoring "pfns[i] = pfn_to_gfn(xen_pfn++)" to a function with parameter pfns[i]. How can we pass pfns[i]? Thanks, -- Shannon