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Date: Tue, 19 Nov 2013 14:35:59 +0000 From: David Vrabel <david.vrabel@...rix.com> To: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com> CC: Elena Ufimtseva <ufimtseva@...il.com>, <xen-devel@...ts.xenproject.org>, <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 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 <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. > > 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. David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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