[PATCH 1/2] x86/cpu: fix BSP detection when running as Xen PV guest

From: Juergen Gross
Date: Fri Apr 05 2024 - 08:35:14 EST


When booting as a Xen PV guest the boot processor isn't detected
correctly and the following message is shown:

CPU topo: Boot CPU APIC ID not the first enumerated APIC ID: 0 > 1

Additionally this results in one CPU being ignored.

Fix that by calling the BSP detection logic when registering the boot
CPU's APIC, too.

Fixes: 5c5682b9f87a ("x86/cpu: Detect real BSP on crash kernels")
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
arch/x86/kernel/cpu/topology.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
index aaca8d235dc2..23c3db5e6396 100644
--- a/arch/x86/kernel/cpu/topology.c
+++ b/arch/x86/kernel/cpu/topology.c
@@ -255,7 +255,7 @@ void __init topology_register_boot_apic(u32 apic_id)
WARN_ON_ONCE(topo_info.boot_cpu_apic_id != BAD_APICID);

topo_info.boot_cpu_apic_id = apic_id;
- topo_register_apic(apic_id, CPU_ACPIID_INVALID, true);
+ topology_register_apic(apic_id, CPU_ACPIID_INVALID, true);
}

/**
--
2.35.3