Messages in this thread | | | Date | Thu, 3 Aug 2023 21:58:04 +0530 | Subject | Re: [PATCH] x86/smp: Validate APIC ID before parking CPU in INIT | From | Vasant Hegde <> |
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Hi
Did you get a chance to look into this patch?
-Vasant
On 7/19/2023 10:43 AM, Vasant Hegde wrote: > Below commit is causing kexec to hang in certain scenarios with >255 CPUs. > > Reproduce steps: > - We are using 2 socket system with 384 CPUs > - Booting first kernel with kernel command line intremap=off > This disabled x2apic in kernel and booted with apic mode > - During kexec it tries to send INIT to all CPUs except boot CPU > If APIC ID is 0x100 (like in our case) then it will send CPU0 > to INIT mode and system hangs (in APIC mode DEST field is 8bit) > > Fix this issue by adding apic->apic_id_valid() check before sending > INIT sequence. > > Fixes: 45e34c8af58f ("x86/smp: Put CPUs into INIT on shutdown if possible") > Reported-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com> > Tested-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com> > Signed-off-by: Vasant Hegde <vasant.hegde@amd.com> > --- > arch/x86/kernel/smpboot.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c > index e1aa2cd7734b..e5ca0689c4dd 100644 > --- a/arch/x86/kernel/smpboot.c > +++ b/arch/x86/kernel/smpboot.c > @@ -1360,7 +1360,7 @@ bool smp_park_other_cpus_in_init(void) > if (cpu == this_cpu) > continue; > apicid = apic->cpu_present_to_apicid(cpu); > - if (apicid == BAD_APICID) > + if (apicid == BAD_APICID || !apic->apic_id_valid(apicid)) > continue; > send_init_sequence(apicid); > }
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