From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: [PATCH RESEND v2 2/2] xen: enable vnuma for PV guest Date: Tue, 19 Nov 2013 09:46:30 -0500 Message-ID: <20131119144630.GA5780__4702.89003937996$1384872599$gmane$org@phenom.dumpdata.com> References: <1384811922-14642-1-git-send-email-ufimtseva@gmail.com> <1384811922-14642-3-git-send-email-ufimtseva@gmail.com> <528B5160.5010902@citrix.com> <20131119141620.GD5332@phenom.dumpdata.com> <528B774F.7090902@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta4.messagelabs.com ([85.158.143.247]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1Vimb7-0003VY-5P for xen-devel@lists.xenproject.org; Tue, 19 Nov 2013 14:48:13 +0000 Content-Disposition: inline In-Reply-To: <528B774F.7090902@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: David Vrabel Cc: akpm@linux-foundation.org, wency@cn.fujitsu.com, stefano.stabellini@eu.citrix.com, x86@kernel.org, linux-kernel@vger.kernel.org, tangchen@cn.fujitsu.com, mingo@redhat.com, Elena Ufimtseva , hpa@zytor.com, xen-devel@lists.xenproject.org, boris.ostrovsky@oracle.com, tglx@linutronix.de, ian.campbell@citrix.com List-Id: xen-devel@lists.xenproject.org On Tue, Nov 19, 2013 at 02:35:59PM +0000, David Vrabel wrote: > On 19/11/13 14:16, Konrad Rzeszutek Wilk wrote: > > On Tue, Nov 19, 2013 at 11:54:08AM +0000, David Vrabel wrote: > >> On 18/11/13 21:58, Elena Ufimtseva wrote: > >>> Enables numa if vnuma topology hypercall is supported and it is domU. > >> [...] > >>> --- a/arch/x86/xen/setup.c > >>> +++ b/arch/x86/xen/setup.c > >>> @@ -20,6 +20,7 @@ > >>> #include > >>> #include > >>> #include > >>> +#include > >>> > >>> #include > >>> #include > >>> @@ -598,6 +599,9 @@ void __init xen_arch_setup(void) > >>> WARN_ON(xen_set_default_idle()); > >>> fiddle_vdso(); > >>> #ifdef CONFIG_NUMA > >>> - numa_off = 1; > >>> + if (!xen_initial_domain() && xen_vnuma_supported()) > >>> + numa_off = 0; > >>> + else > >>> + numa_off = 1; > >>> #endif > >>> } > >> > >> I think this whole #ifdef CONFIG_NUMA can be removed and hence > >> xen_vnuma_supported() can be removed as well. > >> > >> For any PV guest we can call the xen_numa_init() and it will do the > >> right thing. > >> > >> For dom0, the hypercall will either: return something sensible (if in > >> the future Xen sets something up), or it will error. > >> > >> If Xen does not have vnuma support, the hypercall will error. > >> > >> In both error cases, the dummy numa node is setup as required. > > > > Incorrect. It will end up calling: > > > > if (!numa_init(amd_numa_init)) > > > > which will crash dom0 (see 8d54db795 "xen/boot: Disable NUMA for PV guests.") > > as that amd_numa_init is called before the dummy node init. > > No it won't. Any error path after the check for a PV guest will add the > dummy node and return success, skipping any of the hardware-specific setup. Duh! I totally missed 'return' at the end of the check! However, even with that (so the return), that means this part won't be called: 649 numa_init(dummy_numa_init); Which means there won't be any dummy numa setup?