Messages in this thread | | | Date | Tue, 21 Feb 2023 22:04:29 +0100 | From | Oleksandr Natalenko <> | Subject | Re: [External] Re: [PATCH v9 0/8] Parallel CPU bringup for x86_64 |
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On 21.02.2023 21:04, Usama Arif wrote: > On 21/02/2023 19:10, David Woodhouse wrote: >> On Tue, 2023-02-21 at 13:14 +0100, Oleksandr Natalenko wrote: >>> >>> With this in place: >>> >>> ``` >>> early_gdt_descr.address = (unsigned long)get_cpu_gdt_rw(0); >>> initial_gs = per_cpu_offset(0); >>> smpboot_control = 0; >>> ``` >>> >>> the resume does not work. >> >> Yeah, I think it's always running on CPU0 after the other CPUs are >> taken down anyway. >> >> We definitely *do* need to clear smpboot_control because we absolutely >> want it using the temp_stack we explicitly put into initial_stack, not >> finding its own idle thread. >> >> The problem was that it was never being restored to STARTUP_SECONDARY >> in the parallel modes, because that's a one-time setup in >> native_smp_prepare_cpus(). So we can just restore it in >> arch_thaw_secondary_cpus_begin() too, by working this into patch 6 of >> the series. >> >> (Usama, I think my tree is fairly out of date now so I'll let you do >> that? Thanks!). > > Sounds good! Will send out the next revision with below diff, > checkpatch > fixes and rebased to 6.2 (testing it now). The below fix looks good! > Oleksandr, would you mind testing out suspend/resume with the below > diff on your AMD machine just to make sure it fixes the issue before I > send out the next revision with it. Thanks!
Right, so I applied the whole series + this fix, and the suspend/resume works. Thanks!
Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
There's another open question pending though: why would this series cause booting up one CPU only on an older AMD CPU. But I'd expect Piotr's fellow to chime in occasionally.
>> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c >> index 50621793671d..3db77a257ae2 100644 >> --- a/arch/x86/kernel/smpboot.c >> +++ b/arch/x86/kernel/smpboot.c >> @@ -1571,6 +1571,17 @@ void __init native_smp_prepare_cpus(unsigned >> int max_cpus) >> void arch_thaw_secondary_cpus_begin(void) >> { >> + /* >> + * On suspend, smpboot_control will have been zeroed to allow the >> + * boot CPU to use explicitly passed values including a temporary >> + * stack. Since native_smp_prepare_cpus() won't be called again, >> + * restore the appropriate value for the parallel startup modes. >> + */ >> + if (do_parallel_bringup) { >> + smpboot_control = STARTUP_SECONDARY | >> + (x2apic_mode ? STARTUP_APICID_CPUID_0B : STARTUP_APICID_CPUID_01); >> + } >> + >> set_cache_aps_delayed_init(true); >> } >>
-- Oleksandr Natalenko (post-factum)
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