Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752909AbbH1PM3 (ORCPT ); Fri, 28 Aug 2015 11:12:29 -0400 Received: from smtp.citrix.com ([66.165.176.89]:16362 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752572AbbH1PMZ (ORCPT ); Fri, 28 Aug 2015 11:12:25 -0400 X-IronPort-AV: E=Sophos;i="5.17,425,1437436800"; d="scan'208";a="295566203" Message-ID: <55E079E0.3000507@citrix.com> Date: Fri, 28 Aug 2015 16:10:24 +0100 From: Julien Grall User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.8.0 MIME-Version: 1.0 To: David Vrabel , CC: Wei Liu , , , , "Boris Ostrovsky" , Subject: Re: [Xen-devel] [PATCH v3 12/20] xen/balloon: Don't rely on the page granularity is the same for Xen and Linux References: <1438966019-19322-1-git-send-email-julien.grall@citrix.com> <1438966019-19322-13-git-send-email-julien.grall@citrix.com> <55D5A51D.2060106@citrix.com> In-Reply-To: <55D5A51D.2060106@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: 1654 Lines: 49 On 20/08/15 10:59, David Vrabel wrote: > On 07/08/15 17:46, Julien Grall wrote: >> For ARM64 guests, Linux is able to support either 64K or 4K page >> granularity. Although, the hypercall interface is always based on 4K >> page granularity. >> >> With 64K page granularity, a single page will be spread over multiple >> Xen frame. >> >> To avoid splitting the page into 4K frame, take advantage of the >> extent_order field to directly allocate/free chunk of the Linux page >> size. >> >> Note that PVMMU is only used for PV guest (which is x86) and the page >> granularity is always 4KB. Some BUILD_BUG_ON has been added to ensure >> that because the code has not been modified. > [...] >> #ifdef CONFIG_XEN_HAVE_PVMMU >> + /* We don't support PV MMU when Linux and Xen is using >> + * different page granularity. >> + */ >> + BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE); > > You don't need this BUILD_BUG_ON() twice. I put twice the BUILD_BUG_ON so if we ever decide to drop one of the #ifdef CONFIG_XEN_HAVE_PVMMU, the check will still be present. So I'd like to keep it. > Otherwise, > > Reviewed-by: David Vrabel Based on the discussion with Stefano I rework a bit the balloon code to re-use lru field (see [1]), so I won't retain your reviewed-by on the next series. Regards, [1] http://lists.xen.org/archives/html/xen-devel/2015-08/msg00781.html -- Julien Grall -- 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/