From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030216AbbCSRWg (ORCPT ); Thu, 19 Mar 2015 13:22:36 -0400 Received: from smtp.citrix.com ([66.165.176.89]:46289 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756315AbbCSRWb (ORCPT ); Thu, 19 Mar 2015 13:22:31 -0400 X-IronPort-AV: E=Sophos;i="5.11,430,1422921600"; d="scan'208";a="245038211" Message-ID: <550B05B9.3010400@citrix.com> Date: Thu, 19 Mar 2015 17:22:01 +0000 From: David Vrabel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.4.0 MIME-Version: 1.0 To: Juergen Gross , , , , , Subject: Re: [Xen-devel] [PATCH 1/2] xen: prepare p2m list for memory hotplug References: <1426775462-981-1-git-send-email-jgross@suse.com> <1426775462-981-2-git-send-email-jgross@suse.com> <550AF6BA.7060209@citrix.com> <550B0450.6000209@suse.com> In-Reply-To: <550B0450.6000209@suse.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 On 19/03/15 17:16, Juergen Gross wrote: > On 03/19/2015 05:18 PM, David Vrabel wrote: >> On 19/03/15 14:31, Juergen Gross wrote: >>> Commit 054954eb051f35e74b75a566a96fe756015352c8 ("xen: switch to linear >>> virtual mapped sparse p2m list") introduced a regression regarding to >>> memory hotplug for a pv-domain: as the virtual space for the p2m list >>> is allocated for the to be expected memory size of the domain only, >>> hotplugged memory above that size will not be usable by the domain. >>> >>> Correct this by using a configurable size for the p2m list in case of >>> memory hotplug enabled (default supported memory size is 512 GB for >>> 64 bit domains and 4 GB for 32 bit domains). >> [...] >>> --- a/arch/x86/xen/p2m.c >>> +++ b/arch/x86/xen/p2m.c >>> @@ -91,6 +91,17 @@ EXPORT_SYMBOL_GPL(xen_p2m_size); >>> unsigned long xen_max_p2m_pfn __read_mostly; >>> EXPORT_SYMBOL_GPL(xen_max_p2m_pfn); >>> >>> +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT >>> +#ifdef CONFIG_X86_32 >>> +BUILD_BUG_ON_MSG(CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT > 64) >>> +#endif >>> +#define P2M_LIMIT max(xen_max_p2m_pfn, \ >>> + ((unsigned long)((u64)CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT >>> * \ >>> + 1024 * 1024 * 1024 / PAGE_SIZE))) >>> +#else >>> +#define P2M_LIMIT xen_max_p2m_pfn >>> +#endif >> >> Can you arrange the #ifdef's to set xen_max_p2m_pfn to the right value >> instead of introducing P2M_LIMIT? > > Hmm, this would require additional checks in setup.c. What about: > > #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT > #define P2M_LIMIT CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT > #else > #define P2M_LIMIT 0 > #endif > > and do the max(...) calculation in xen_vmalloc_p2m_tree()? Yes, this is fine. David