[Xen-devel] [PATCH] x86/xen: disable cpu0 hotplug for xen pv

[Juergen Gross <jgross@xxxxxxxx>]

Xen pv guests don't allow cpu0 hotplug, so disable it.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 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;
 
        /*
-- 
2.16.4


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