On 09/02/2023 10:06, David Woodhouse wrote:
On Thu, 2023-02-09 at 09:49 +0000, Usama Arif wrote:
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1080,6 +1080,7 @@ wakeup_cpu_via_init_nmi(int cpu, unsigned long
start_ip, int apicid,
wakeup_cpu0_nmi, 0, "wake_cpu0");
if (!boot_error) {
+ initial_gs = per_cpu_offset(cpu);
That's for 64-bit.
enable_start_cpu0 = 1;
*cpu0_nmi_registered = 1;
id = apic->dest_mode_logical ? cpu0_logical_apicid :
apicid;
@@ -1188,10 +1189,14 @@ static int do_boot_cpu(int apicid, int cpu,
struct task_struct *idle,
boot_error = apic->wakeup_secondary_cpu_64(apicid,
start_ip);
else if (apic->wakeup_secondary_cpu)
boot_error = apic->wakeup_secondary_cpu(apicid, start_ip);
- else
+ else {
+ if(!cpu) {
+ early_gdt_descr.address = (unsigned long)get_cpu_gdt_rw(cpu);
+ initial_stack = idle->thread.sp;
+ }
And that's 32-bit.
These were previously done in common_cpu_up() or do_boot_cpu(), which
means they were done not only for the wakeup_cpu_via_init_nmi() code
path, but also when we call apic->wakeup_secondary_cpu() (or _64()) for
the esoteric UV/NumaConnect machines.
Thanks for diagnosing it so quickly; I'll work up a subtly different
fix.
Yeah, was just a hacky fix while I was trying to figure out the issue.
do_boot_cpu is only called in cpu0 in hotplug case, so I think this a
much better diff:
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 3ec5182d9698..f7ae82969ee4 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1136,13 +1136,16 @@ static int do_boot_cpu(int apicid, int cpu,
struct task_struct *idle,
idle->thread.sp = (unsigned long)task_pt_regs(idle);
initial_code = (unsigned long)start_secondary;
- if (IS_ENABLED(CONFIG_X86_32)) {
+ if (IS_ENABLED(CONFIG_X86_32) || !cpu) {
early_gdt_descr.address = (unsigned
long)get_cpu_gdt_rw(cpu);
initial_stack = idle->thread.sp;
} else if (!do_parallel_bringup) {
smpboot_control = STARTUP_SECONDARY | apicid;
}
+ if (!cpu)
+ initial_gs = per_cpu_offset(cpu);
+
/* Enable the espfix hack for this CPU */
init_espfix_ap(cpu);
boot_error = wakeup_cpu_via_init_nmi(cpu, start_ip, apicid,
cpu0_nmi_registered);
-
+ }
return boot_error;
}
