From 8a95db3bf8a32186fe448b1a934afbd5f1da0263 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 2 May 2024 16:39:47 +0200 Subject: x86/xen/smp_pv: Register the boot CPU APIC properly The topology core expects the boot APIC to be registered from earhy APIC detection first and then again when the firmware tables are evaluated. This is used for detecting the real BSP CPU on a kexec kernel. The recent conversion of XEN/PV to register fake APIC IDs failed to register the boot CPU APIC correctly as it only registers it once. This causes the BSP detection mechanism to trigger wrongly: CPU topo: Boot CPU APIC ID not the first enumerated APIC ID: 0 > 1 Additionally this results in one CPU being ignored. Register the boot CPU APIC twice so that the XEN/PV fake enumeration behaves like real firmware. Reported-by: Juergen Gross Fixes: e75307023466 ("x86/xen/smp_pv: Register fake APICs") Signed-off-by: Thomas Gleixner Tested-by: Juergen Gross Reviewed-by: Juergen Gross Link: https://lore.kernel.org/r/87a5l8s2fg.ffs@tglx Signed-off-by: Juergen Gross --- arch/x86/xen/smp_pv.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c index 27d1a5b7f571..ac41d83b38d3 100644 --- a/arch/x86/xen/smp_pv.c +++ b/arch/x86/xen/smp_pv.c @@ -154,9 +154,9 @@ static void __init xen_pv_smp_config(void) u32 apicid = 0; int i; - topology_register_boot_apic(apicid++); + topology_register_boot_apic(apicid); - for (i = 1; i < nr_cpu_ids; i++) + for (i = 0; i < nr_cpu_ids; i++) topology_register_apic(apicid++, CPU_ACPIID_INVALID, true); /* Pretend to be a proper enumerated system */ -- cgit v1.2.3