linux-kernel - Re: [PATCH RESEND v2 2/2] xen: enable vnuma for PV guest

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Date:	Tue, 19 Nov 2013 11:54:08 +0000
From:	David Vrabel <david.vrabel@...rix.com>
To:	Elena Ufimtseva <ufimtseva@...il.com>
CC:	<xen-devel@...ts.xenproject.org>, <konrad.wilk@...cle.com>,
	<boris.ostrovsky@...cle.com>, <tglx@...utronix.de>,
	<mingo@...hat.com>, <hpa@...or.com>, <x86@...nel.org>,
	<akpm@...ux-foundation.org>, <tangchen@...fujitsu.com>,
	<wency@...fujitsu.com>, <ian.campbell@...rix.com>,
	<stefano.stabellini@...citrix.com>, <mukesh.rathor@...cle.com>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RESEND v2 2/2] xen: enable vnuma for PV guest

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 <asm/numa.h>
>  #include <asm/xen/hypervisor.h>
>  #include <asm/xen/hypercall.h>
> +#include <asm/xen/vnuma.h>
>  
>  #include <xen/xen.h>
>  #include <xen/page.h>
> @@ -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.

If you do this, you can fold this change in with the previous patch.

David
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