6.5-stable review patch. If anyone has any objections, please let me know.
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From: Thomas Gleixner tglx@linutronix.de
commit 3f874c9b2aae8e30463efc1872bea4baa9ed25dc upstream.
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: 45e34c8af58f ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/smpboot.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1356,7 +1356,7 @@ 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);