Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753785AbbGXJgR (ORCPT ); Fri, 24 Jul 2015 05:36:17 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:1058 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750931AbbGXJgP (ORCPT ); Fri, 24 Jul 2015 05:36:15 -0400 X-IronPort-AV: E=Sophos;i="5.15,537,1432598400"; d="scan'208";a="287203053" Message-ID: <55B206F0.3060108@citrix.com> Date: Fri, 24 Jul 2015 10:35:44 +0100 From: David Vrabel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.7.0 MIME-Version: 1.0 To: Julien Grall , CC: , , "Julien Grall" , , David Vrabel , Boris Ostrovsky , Subject: Re: [Xen-devel] [PATCH v2 04/20] xen/grant: Add helper gnttab_page_grant_foreign_access_ref References: <1436474552-31789-1-git-send-email-julien.grall@citrix.com> <1436474552-31789-5-git-send-email-julien.grall@citrix.com> In-Reply-To: <1436474552-31789-5-git-send-email-julien.grall@citrix.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-DLP: MIA1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1655 Lines: 45 On 09/07/15 21:42, Julien Grall wrote: > Many PV drivers contain the idiom: > > pfn = page_to_mfn(...) /* Or similar */ > gnttab_grant_foreign_access_ref > > Replace it by a new helper. Note that when Linux is using a different > page granularity than Xen, the helper only gives access to the first 4KB > grant. > > This is useful where drivers are allocating a full Linux page for each > grant. > > Also include xen/interface/grant_table.h rather than xen/grant_table.h in > asm/page.h for x86 to fix a compilation issue [1]. Only the former is > useful in order to get the structure definition. > > [1] Interpendency between asm/page.h and xen/grant_table.h which result > to page_mfn not being defined when necessary. [...] > --- a/include/xen/grant_table.h > +++ b/include/xen/grant_table.h > @@ -131,6 +131,15 @@ void gnttab_cancel_free_callback(struct gnttab_free_callback *callback); > void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid, > unsigned long frame, int readonly); > > +/* Give access to the first 4K of the page */ > +static inline void gnttab_page_grant_foreign_access_ref( > + grant_ref_t ref, domid_t domid, > + struct page *page, int readonly) > +{ > + gnttab_grant_foreign_access_ref(ref, domid, page_to_mfn(page), Obviously this would use the new xen_page_to_gfn() macro here. Otherwise, Reviewed-by: David Vrabel David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/