From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: [PATCH v7 03/17] Xen: xlate: Use page_to_xen_pfn instead of page_to_pfn Date: Wed, 30 Mar 2016 12:22:49 +0100 Message-ID: <56FBB709.5050802@arm.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> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <56FB8258.7030303-hv44wF8Li93QT0dZR+AlfA@public.gmane.org> Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Shannon Zhao , Shannon Zhao , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, stefano.stabellini-Sxgqhf6Nn4DQT0dZR+AlfA@public.gmane.org, david.vrabel-Sxgqhf6Nn4DQT0dZR+AlfA@public.gmane.org Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, catalin.marinas-5wv7dgnIgG8@public.gmane.org, will.deacon-5wv7dgnIgG8@public.gmane.org, peter.huangpeng-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, xen-devel-GuqFBffKawuEi8DpZVb4nw@public.gmane.org List-Id: devicetree@vger.kernel.org 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); Regards, -- Julien Grall