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x86/smp: Don't send INIT to non-present and non-booted CPUs
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Vasant reported that kexec() can hang or reset the machine when it tries to
park CPUs via INIT. This happens when the kernel is using extended APIC,
but the present mask has APIC IDs >= 0x100 enumerated.

As extended APIC can only handle 8 bit of APIC ID sending INIT to APIC ID
0x100 sends INIT to APIC ID 0x0. That's the boot CPU which is special on
x86 and INIT causes the system to hang or resets the machine.

Prevent this by sending INIT only to those CPUs which have been booted
once.

Fixes: 45e34c8 ("x86/smp: Put CPUs into INIT on shutdown if possible")
Reported-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Vasant Hegde <vasant.hegde@amd.com>
Link: https://lore.kernel.org/r/87cyzwjbff.ffs@tglx
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Thomas Gleixner committed Sep 4, 2023
1 parent 6ea7bb0 commit 3f874c9
Showing 1 changed file with 1 addition and 1 deletion.
2 changes: 1 addition & 1 deletion arch/x86/kernel/smpboot.c
Original file line number Diff line number Diff line change
Expand Up @@ -1250,7 +1250,7 @@ bool smp_park_other_cpus_in_init(void)
if (this_cpu)
return false;

for_each_present_cpu(cpu) {
for_each_cpu_and(cpu, &cpus_booted_once_mask, cpu_present_mask) {
if (cpu == this_cpu)
continue;
apicid = apic->cpu_present_to_apicid(cpu);
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