From: Kuppuswamy Sathyanarayanan Date: Sat, 16 Apr 2022 02:45:32 +0000 (+0000) Subject: x86/apic: Do apic driver probe for "nosmp" use case X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=7a116a2dd32d96869f0f93bac00b900859ba0434;p=linux.git x86/apic: Do apic driver probe for "nosmp" use case For the "nosmp" use case, the APIC initialization code selects "APIC_SYMMETRIC_IO_NO_ROUTING" as the default interrupt mode and avoids probing APIC drivers. This works well for the default APIC modes, but for the x2APIC case the probe function is required to allocate the cluster_hotplug mask. So in the APIC_SYMMETRIC_IO_NO_ROUTING case when the x2APIC is initialized it dereferences a NULL pointer and the kernel crashes. This was observed on a TDX platform where x2APIC is enabled and "nosmp" command line option is allowed. To fix this issue, probe APIC drivers via default_setup_apic_routing() for the APIC_SYMMETRIC_IO_NO_ROUTING interrupt mode too. Suggested-by: Kirill A. Shutemov Suggested-by: Rafael J. Wysocki Signed-off-by: Kuppuswamy Sathyanarayanan Signed-off-by: Thomas Gleixner Reviewed-by: Tony Luck Link: https://lore.kernel.org/r/a64f864e1114bcd63593286aaf61142cfce384ea.1650076869.git.sathyanarayanan.kuppuswamy@intel.com --- diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 13819bfa8dde7..25e92d7a7ae5a 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -1428,22 +1428,21 @@ void __init apic_intr_mode_init(void) return; case APIC_VIRTUAL_WIRE: pr_info("APIC: Switch to virtual wire mode setup\n"); - default_setup_apic_routing(); break; case APIC_VIRTUAL_WIRE_NO_CONFIG: pr_info("APIC: Switch to virtual wire mode setup with no configuration\n"); upmode = true; - default_setup_apic_routing(); break; case APIC_SYMMETRIC_IO: pr_info("APIC: Switch to symmetric I/O mode setup\n"); - default_setup_apic_routing(); break; case APIC_SYMMETRIC_IO_NO_ROUTING: pr_info("APIC: Switch to symmetric I/O mode setup in no SMP routine\n"); break; } + default_setup_apic_routing(); + if (x86_platform.apic_post_init) x86_platform.apic_post_init();