Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752622AbcC3Mmd (ORCPT ); Wed, 30 Mar 2016 08:42:33 -0400 Received: from mail-pa0-f45.google.com ([209.85.220.45]:35183 "EHLO mail-pa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751432AbcC3Mmb (ORCPT ); Wed, 30 Mar 2016 08:42:31 -0400 Subject: Re: [PATCH v7 03/17] Xen: xlate: Use page_to_xen_pfn instead of page_to_pfn To: Julien Grall , Shannon Zhao , linux-arm-kernel@lists.infradead.org, stefano.stabellini@citrix.com, david.vrabel@citrix.com 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> <56FB8258.7030303@huawei.com> <56FBB709.5050802@arm.com> Cc: devicetree@vger.kernel.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, will.deacon@arm.com, peter.huangpeng@huawei.com, xen-devel@lists.xen.org From: Shannon Zhao Message-ID: <56FBC9AC.1070203@linaro.org> Date: Wed, 30 Mar 2016 20:42:20 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <56FBB709.5050802@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3229 Lines: 95 On 2016年03月30日 19:22, Julien Grall wrote: > Hi Shannon, > > On 30/03/16 08:38, Shannon Zhao wrote: >> >> >> On 2016/3/30 0:28, Julien Grall wrote: >>> 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]? > > By using the variable data. Something along those lines: > > struct map_balloon_pages > { > xen_pfn_t *pfns; > unsigned int idx; > }; > > static void setup_balloon_gfn(unsigned long gfn, void *data) > { > struct map_balloon_pages *info = data; > > > data->pfns[data->idx] = gfn; > data->idx++; > } > > And then in xen_xlate_map_ballooned_pages > > xen_for_each_gfn(pages, nr_grant_frames, setup_balloon_gfn, &data); I think this looks like less direct. Anyway I will update this patch as you said. Thanks, -- Shannon