From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757210AbbCSRVq (ORCPT ); Thu, 19 Mar 2015 13:21:46 -0400 Received: from cantor2.suse.de ([195.135.220.15]:57928 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932190AbbCSRFu (ORCPT ); Thu, 19 Mar 2015 13:05:50 -0400 Message-ID: <550B01EC.1030002@suse.com> Date: Thu, 19 Mar 2015 18:05:48 +0100 From: Juergen Gross User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Daniel Kiper CC: linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com, konrad.wilk@oracle.com, david.vrabel@citrix.com, boris.ostrovsky@oracle.com Subject: Re: [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> <20150319161440.GF27971@olila.local.net-space.pl> In-Reply-To: <20150319161440.GF27971@olila.local.net-space.pl> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/19/2015 05:14 PM, Daniel Kiper wrote: > On Thu, Mar 19, 2015 at 03:31:01PM +0100, 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). >> >> Signed-off-by: Juergen Gross >> --- >> arch/x86/xen/p2m.c | 13 ++++++++++++- >> drivers/xen/Kconfig | 13 +++++++++++++ >> 2 files changed, 25 insertions(+), 1 deletion(-) >> >> diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c >> index 9f93af5..30e84ae 100644 >> --- 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 >> + >> static DEFINE_SPINLOCK(p2m_update_lock); >> >> static unsigned long *p2m_mid_missing_mfn; >> @@ -387,7 +398,7 @@ void __init xen_vmalloc_p2m_tree(void) >> static struct vm_struct vm; >> >> vm.flags = VM_ALLOC; >> - vm.size = ALIGN(sizeof(unsigned long) * xen_max_p2m_pfn, >> + vm.size = ALIGN(sizeof(unsigned long) * P2M_LIMIT, >> PMD_SIZE * PMDS_PER_MID_PAGE); > > What happens when somebody will allocate more memory for guest than > XEN_BALLOON_MEMORY_HOTPLUG_LIMIT? Additionally, I think that we do It will fail to add like it does without this patch. > not need allocate extra virtual address space if memory hotplug is > disabled. As XEN_BALLOON_MEMORY_HOTPLUG_LIMIT depends on XEN_BALLOON_MEMORY_HOTPLUG which in turn depends on MEMORY_HOTPLUG, this is already the case. > >> vm_area_register_early(&vm, PMD_SIZE * PMDS_PER_MID_PAGE); >> pr_notice("p2m virtual area at %p, size is %lx\n", vm.addr, vm.size); >> diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig >> index b812462..0a61ddf 100644 >> --- a/drivers/xen/Kconfig >> +++ b/drivers/xen/Kconfig >> @@ -55,6 +55,19 @@ config XEN_BALLOON_MEMORY_HOTPLUG >> >> In that case step 3 should be omitted. >> >> +config XEN_BALLOON_MEMORY_HOTPLUG_LIMIT >> + int >> + default 512 if X86_64 >> + default 4 if X86_32 >> + depends on XEN_HAVE_PVMMU > > Do we need dependency on XEN_HAVE_PVMMU? Yes. Needed only for pv domains. > If yes than maybe "depends on XEN_HAVE_PVMMU && XEN_BALLOON_MEMORY_HOTPLUG". Matter of taste, I guess. > >> + depends on XEN_BALLOON_MEMORY_HOTPLUG > > Should not this option be available even when memory hotplug is disabled? Why? Juergen