From 999696752db1099aba595aac4f8d881f8c7cf4e6 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Wed, 12 Sep 2018 19:41:22 +0200 Subject: [PATCH] x86/xen: Disable CPU0 hotplug for Xen PV Xen PV guests don't allow CPU0 hotplug, so disable it. Signed-off-by: Juergen Gross Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: boris.ostrovsky@oracle.com Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/20180912174122.24282-1-jgross@suse.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/topology.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c index 12cbe2b88c0f..738bf42b0218 100644 --- a/arch/x86/kernel/topology.c +++ b/arch/x86/kernel/topology.c @@ -111,8 +111,10 @@ int arch_register_cpu(int num) /* * Currently CPU0 is only hotpluggable on Intel platforms. Other * vendors can add hotplug support later. + * Xen PV guests don't support CPU0 hotplug at all. */ - if (c->x86_vendor != X86_VENDOR_INTEL) + if (c->x86_vendor != X86_VENDOR_INTEL || + boot_cpu_has(X86_FEATURE_XENPV)) cpu0_hotpluggable = 0; /*