From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [PATCH v2 01/20] xen: Add Xen specific page definition Date: Fri, 24 Jul 2015 11:34:45 +0100 Message-ID: <55B214C5.3020501__12179.758368484$1437734170$gmane$org@citrix.com> References: <1436474552-31789-1-git-send-email-julien.grall@citrix.com> <1436474552-31789-2-git-send-email-julien.grall@citrix.com> <55B20540.3020000@citrix.com> <55B207C6.4020300@citrix.com> <55B209D9.1080602@citrix.com> <55B20ABE.7000609@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1ZIaJa-0004dE-5O for xen-devel@lists.xenproject.org; Fri, 24 Jul 2015 10:34:54 +0000 In-Reply-To: <55B20ABE.7000609@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Julien Grall , xen-devel@lists.xenproject.org Cc: Boris Ostrovsky , stefano.stabellini@eu.citrix.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, ian.campbell@citrix.com List-Id: xen-devel@lists.xenproject.org On 24/07/15 10:51, Julien Grall wrote: > On 24/07/15 10:48, David Vrabel wrote: >> On 24/07/15 10:39, Julien Grall wrote: >>> Hi David, >>> >>> On 24/07/15 10:28, David Vrabel wrote: >>>> On 09/07/15 21:42, Julien Grall wrote: >>>>> The Xen hypercall interface is always using 4K page granularity on ARM >>>>> and x86 architecture. >>>>> >>>>> With the incoming support of 64K page granularity for ARM64 guest, it >>>>> won't be possible to re-use the Linux page definition in Xen drivers. >>>>> >>>>> Introduce Xen page definition helpers based on the Linux page >>>>> definition. They have exactly the same name but prefixed with >>>>> XEN_/xen_ prefix. >>>>> >>>>> Also modify page_to_pfn to use new Xen page definition. >>>>> >>>>> Signed-off-by: Julien Grall >>>>> Cc: Konrad Rzeszutek Wilk >>>>> Cc: Boris Ostrovsky >>>>> Cc: David Vrabel >>>>> --- >>>>> I'm wondering if we should drop page_to_pfn has the macro will likely >>>>> misuse when Linux is using 64KB page granularity. >>>> >>>> I think we want xen_gfn_to_page() and xen_page_to_gfn() and Xen >>>> front/back drivers never deal with PFNs only GFNs. >>> >>> What is xen_gfn_to_page and xen_page_to_gfn? Neither Linux, nor my >>> series have them. >> >> I suggesting that you introduce these. > > It's still not clear to me what you are suggesting here... Do you > suggest to rename xen_pfn_to_page and xen_page_to_pfn by xen_gfn_to_page > and xen_page_to_gfn? Effectively, yes but it would be better to think that: PFNs index guest-sized pages (which may be 64 KiB). GFNs index Xen-sized pages (which is always 4 KiB). David