Commit-ID:  999696752db1099aba595aac4f8d881f8c7cf4e6
Gitweb:     https://git.kernel.org/tip/999696752db1099aba595aac4f8d881f8c7cf4e6
Author:     Juergen Gross <[email protected]>
AuthorDate: Wed, 12 Sep 2018 19:41:22 +0200
Committer:  Ingo Molnar <[email protected]>
CommitDate: Wed, 12 Sep 2018 21:15:02 +0200

x86/xen: Disable CPU0 hotplug for Xen PV

Xen PV guests don't allow CPU0 hotplug, so disable it.

Signed-off-by: Juergen Gross <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
 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;
 
        /*

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