Messages in this thread Patch in this message | | | Date | Wed, 22 Feb 2023 00:00:27 +0000 | Subject | Re: [External] Re: [PATCH v9 0/8] Parallel CPU bringup for x86_64 | From | Usama Arif <> |
| |
On 21/02/2023 23:18, David Woodhouse wrote: > On Tue, 2023-02-21 at 22:41 +0100, Thomas Gleixner wrote: >> >> @@ -57,6 +58,7 @@ asmlinkage acpi_status __visible x86_acp >> */ >> int x86_acpi_suspend_lowlevel(void) >> { >> + unsigned int __maybe_unused saved_smpboot_ctrl; >> struct wakeup_header *header = >> (struct wakeup_header *) __va(real_mode_header->wakeup_header); >> >> @@ -115,7 +117,8 @@ int x86_acpi_suspend_lowlevel(void) >> early_gdt_descr.address = >> (unsigned long)get_cpu_gdt_rw(smp_processor_id()); >> initial_gs = per_cpu_offset(smp_processor_id()); >> - smpboot_control = 0; >> + /* Force the startup into boot mode */ >> + saved_smpboot_ctrl = xchg(&smpboot_control, 0); >> #endif >> initial_code = (unsigned long)wakeup_long64; >> saved_magic = 0x123456789abcdef0L; >> @@ -128,6 +131,9 @@ int x86_acpi_suspend_lowlevel(void) >> pause_graph_tracing(); >> do_suspend_lowlevel(); >> unpause_graph_tracing(); >> + >> + if (IS_ENABLED(CONFIG_64BIT) && IS_ENABLED(CONFIG_SMP)) >> + smpboot_control = saved_smpboot_ctrl; >> return 0; >> } >> > > But wait, why is this giving it a dedicated temp_stack anyway? Why > can't it use that CPU's idle thread stack like we usually do? I already > made idle_thread_get() accessible from here. So we could do this... > > @@ -111,14 +112,16 @@ int x86_acpi_suspend_lowlevel(void) > saved_magic = 0x12345678; > #else /* CONFIG_64BIT */ > #ifdef CONFIG_SMP > - initial_stack = (unsigned long)temp_stack + sizeof(temp_stack); > - early_gdt_descr.address = > - (unsigned long)get_cpu_gdt_rw(smp_processor_id()); > - initial_gs = per_cpu_offset(smp_processor_id()); > - smpboot_control = 0; > + if (!(smpboot_control & STARTUP_PARALLEL_MASK)) { > + unsigned int cpu = smp_processor_id(); > + initial_stack = (unsigned long)idle_thread_get(cpu)->thread.sp; > + early_gdt_descr.address = (unsigned long)get_cpu_gdt_rw(cpu); > + initial_gs = per_cpu_offset(cpu); > + smpboot_control = 0; > + } > #endif > initial_code = (unsigned long)wakeup_long64; > > > But that's a whole bunch of pointless, because it can be even further > simplified to just let the find its own crap like the secondaries do, > except in the 'OMG CPUID won't tell me' case where it has to be told: > > So how about we just do something more like this. I'd *quite* like to > put the actual handling of smpboot_control into a function we call in > smpboot.c. and that whole x86_acpi_suspend_lowlevel() function wants > all its horrid 64bit/smp ifdefs fixed up (and is there any reason > there's a generic part saving CR0 and IA32_MISC_ENABLE right in the > middle of some !CONFIG_64BIT parts? I don't see ordering constraints > there). But this should work, I think: > > diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h > index 33c0d5fd8af6..72b9375fec7c 100644 > --- a/arch/x86/include/asm/smp.h > +++ b/arch/x86/include/asm/smp.h > @@ -208,4 +208,6 @@ extern unsigned int smpboot_control; > #define STARTUP_APICID_CPUID_0B 0x40000000 > #define STARTUP_APICID_CPUID_01 0x20000000 > > +#define STARTUP_PARALLEL_MASK 0x60000000 > +
Probably could define STARTUP_PARALLEL_MASK as STARTUP_APICID_CPUID_0B | STARTUP_APICID_CPUID_01 instead? otherwise if its a separate bit, it needs to be set in native_smp_prepare_cpus as well for this to work?
> #endif /* _ASM_X86_SMP_H */ > diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c > index 06adf340a0f1..a1343a900caf 100644 > --- a/arch/x86/kernel/acpi/sleep.c > +++ b/arch/x86/kernel/acpi/sleep.c > @@ -16,17 +16,14 @@ > #include <asm/cacheflush.h> > #include <asm/realmode.h> > #include <asm/hypervisor.h> > - > +#include <asm/smp.h> > +#include <linux/smpboot.h> > #include <linux/ftrace.h> > #include "../../realmode/rm/wakeup.h" > #include "sleep.h" > > unsigned long acpi_realmode_flags; > > -#if defined(CONFIG_SMP) && defined(CONFIG_64BIT) > -static char temp_stack[4096]; > -#endif > - > /** > * acpi_get_wakeup_address - provide physical address for S3 wakeup > * > @@ -111,14 +108,11 @@ int x86_acpi_suspend_lowlevel(void) > saved_magic = 0x12345678; > #else /* CONFIG_64BIT */ > #ifdef CONFIG_SMP > - initial_stack = (unsigned long)temp_stack + sizeof(temp_stack); > - early_gdt_descr.address = > - (unsigned long)get_cpu_gdt_rw(smp_processor_id()); > - initial_gs = per_cpu_offset(smp_processor_id()); > - smpboot_control = 0; > + if (!(smpboot_control & STARTUP_PARALLEL_MASK)) > + smpboot_control = STARTUP_SECONDARY | cpu_physical_id(smp_processor_id()); > #endif > initial_code = (unsigned long)wakeup_long64; > - saved_magic = 0x123456789abcdef0L; > + saved_magic = 0x123456789abcdef0L; > #endif /* CONFIG_64BIT */ > > /* > >
| |