Messages in this thread | | | From | Brian Gerst <> | Date | Wed, 1 Apr 2020 07:39:16 -0400 | Subject | Re: [PATCH v2] x86/smpboot: Remove 486-isms from the modern AP boot path |
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On Wed, Apr 1, 2020 at 5:22 AM Andrew Cooper <andrew.cooper3@citrix.com> wrote: > > On 31/03/2020 23:53, Brian Gerst wrote: > > On Tue, Mar 31, 2020 at 6:44 PM Andrew Cooper <andrew.cooper3@citrix.com> wrote: > >> On 31/03/2020 23:23, Brian Gerst wrote: > >>> On Tue, Mar 31, 2020 at 1:59 PM Andrew Cooper <andrew.cooper3@citrix.com> wrote: > >>>> Linux has an implementation of the Universal Start-up Algorithm (MP spec, > >>>> Appendix B.4, Application Processor Startup), which includes unconditionally > >>>> writing to the Bios Data Area and CMOS registers. > >>>> > >>>> The warm reset vector is only necessary in the non-integrated Local APIC case. > >>>> UV and Jailhouse already have an opt-out for this behaviour, but blindly using > >>>> the BDA and CMOS on a UEFI or other reduced hardware system isn't clever. > >>>> > >>>> We could make this conditional on the integrated-ness of the Local APIC, but > >>>> 486-era SMP isn't supported. Drop the logic completely, tidying up the includ > >>>> list and header files as appropriate. > >>>> > >>>> CC: Thomas Gleixner <tglx@linutronix.de> > >>>> CC: Ingo Molnar <mingo@redhat.com> > >>>> CC: Borislav Petkov <bp@alien8.de> > >>>> CC: "H. Peter Anvin" <hpa@zytor.com> > >>>> CC: x86@kernel.org > >>>> CC: Jan Kiszka <jan.kiszka@siemens.com> > >>>> CC: James Morris <jmorris@namei.org> > >>>> CC: David Howells <dhowells@redhat.com> > >>>> CC: Andrew Cooper <andrew.cooper3@citrix.com> > >>>> CC: Matthew Garrett <mjg59@google.com> > >>>> CC: Josh Boyer <jwboyer@redhat.com> > >>>> CC: Steve Wahl <steve.wahl@hpe.com> > >>>> CC: Mike Travis <mike.travis@hpe.com> > >>>> CC: Dimitri Sivanich <dimitri.sivanich@hpe.com> > >>>> CC: Arnd Bergmann <arnd@arndb.de> > >>>> CC: "Peter Zijlstra (Intel)" <peterz@infradead.org> > >>>> CC: Giovanni Gherdovich <ggherdovich@suse.cz> > >>>> CC: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com> > >>>> CC: Len Brown <len.brown@intel.com> > >>>> CC: Kees Cook <keescook@chromium.org> > >>>> CC: Martin Molnar <martin.molnar.programming@gmail.com> > >>>> CC: Pingfan Liu <kernelfans@gmail.com> > >>>> CC: linux-kernel@vger.kernel.org > >>>> CC: jailhouse-dev@googlegroups.com > >>>> Suggested-by: "H. Peter Anvin" <hpa@zytor.com> > >>>> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> > >>>> --- > >>>> v2: > >>>> * Drop logic entirely, rather than retaining support in 32bit builds. > >>>> --- > >>>> arch/x86/include/asm/apic.h | 6 ----- > >>>> arch/x86/include/asm/x86_init.h | 1 - > >>>> arch/x86/kernel/apic/x2apic_uv_x.c | 1 - > >>>> arch/x86/kernel/jailhouse.c | 1 - > >>>> arch/x86/kernel/platform-quirks.c | 1 - > >>>> arch/x86/kernel/smpboot.c | 50 -------------------------------------- > >>>> 6 files changed, 60 deletions(-) > >>>> > >>>> diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h > >>>> index 19e94af9cc5d..5c33f9374b28 100644 > >>>> --- a/arch/x86/include/asm/apic.h > >>>> +++ b/arch/x86/include/asm/apic.h > >>>> @@ -472,12 +472,6 @@ static inline unsigned default_get_apic_id(unsigned long x) > >>>> return (x >> 24) & 0x0F; > >>>> } > >>>> > >>>> -/* > >>>> - * Warm reset vector position: > >>>> - */ > >>>> -#define TRAMPOLINE_PHYS_LOW 0x467 > >>>> -#define TRAMPOLINE_PHYS_HIGH 0x469 > >>>> - > >>>> extern void generic_bigsmp_probe(void); > >>>> > >>>> #ifdef CONFIG_X86_LOCAL_APIC > >>>> diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h > >>>> index 96d9cd208610..006a5d7fd7eb 100644 > >>>> --- a/arch/x86/include/asm/x86_init.h > >>>> +++ b/arch/x86/include/asm/x86_init.h > >>>> @@ -229,7 +229,6 @@ enum x86_legacy_i8042_state { > >>>> struct x86_legacy_features { > >>>> enum x86_legacy_i8042_state i8042; > >>>> int rtc; > >>>> - int warm_reset; > >>>> int no_vga; > >>>> int reserve_bios_regions; > >>>> struct x86_legacy_devices devices; > >>>> diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c > >>>> index ad53b2abc859..5afcfd193592 100644 > >>>> --- a/arch/x86/kernel/apic/x2apic_uv_x.c > >>>> +++ b/arch/x86/kernel/apic/x2apic_uv_x.c > >>>> @@ -343,7 +343,6 @@ static int __init uv_acpi_madt_oem_check(char *_oem_id, char *_oem_table_id) > >>>> } else if (!strcmp(oem_table_id, "UVH")) { > >>>> /* Only UV1 systems: */ > >>>> uv_system_type = UV_NON_UNIQUE_APIC; > >>>> - x86_platform.legacy.warm_reset = 0; > >>>> __this_cpu_write(x2apic_extra_bits, pnodeid << uvh_apicid.s.pnode_shift); > >>>> uv_set_apicid_hibit(); > >>>> uv_apic = 1; > >>>> diff --git a/arch/x86/kernel/jailhouse.c b/arch/x86/kernel/jailhouse.c > >>>> index 6eb8b50ea07e..d628fe92d6af 100644 > >>>> --- a/arch/x86/kernel/jailhouse.c > >>>> +++ b/arch/x86/kernel/jailhouse.c > >>>> @@ -210,7 +210,6 @@ static void __init jailhouse_init_platform(void) > >>>> x86_platform.calibrate_tsc = jailhouse_get_tsc; > >>>> x86_platform.get_wallclock = jailhouse_get_wallclock; > >>>> x86_platform.legacy.rtc = 0; > >>>> - x86_platform.legacy.warm_reset = 0; > >>>> x86_platform.legacy.i8042 = X86_LEGACY_I8042_PLATFORM_ABSENT; > >>>> > >>>> legacy_pic = &null_legacy_pic; > >>>> diff --git a/arch/x86/kernel/platform-quirks.c b/arch/x86/kernel/platform-quirks.c > >>>> index b348a672f71d..d922c5e0c678 100644 > >>>> --- a/arch/x86/kernel/platform-quirks.c > >>>> +++ b/arch/x86/kernel/platform-quirks.c > >>>> @@ -9,7 +9,6 @@ void __init x86_early_init_platform_quirks(void) > >>>> { > >>>> x86_platform.legacy.i8042 = X86_LEGACY_I8042_EXPECTED_PRESENT; > >>>> x86_platform.legacy.rtc = 1; > >>>> - x86_platform.legacy.warm_reset = 1; > >>>> x86_platform.legacy.reserve_bios_regions = 0; > >>>> x86_platform.legacy.devices.pnpbios = 1; > >>>> > >>>> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c > >>>> index fe3ab9632f3b..a9f5b511d0b4 100644 > >>>> --- a/arch/x86/kernel/smpboot.c > >>>> +++ b/arch/x86/kernel/smpboot.c > >>>> @@ -72,7 +72,6 @@ > >>>> #include <asm/fpu/internal.h> > >>>> #include <asm/setup.h> > >>>> #include <asm/uv/uv.h> > >>>> -#include <linux/mc146818rtc.h> > >>>> #include <asm/i8259.h> > >>>> #include <asm/misc.h> > >>>> #include <asm/qspinlock.h> > >>>> @@ -119,34 +118,6 @@ int arch_update_cpu_topology(void) > >>>> return retval; > >>>> } > >>>> > >>>> -static inline void smpboot_setup_warm_reset_vector(unsigned long start_eip) > >>>> -{ > >>>> - unsigned long flags; > >>>> - > >>>> - spin_lock_irqsave(&rtc_lock, flags); > >>>> - CMOS_WRITE(0xa, 0xf); > >>>> - spin_unlock_irqrestore(&rtc_lock, flags); > >>>> - *((volatile unsigned short *)phys_to_virt(TRAMPOLINE_PHYS_HIGH)) = > >>>> - start_eip >> 4; > >>>> - *((volatile unsigned short *)phys_to_virt(TRAMPOLINE_PHYS_LOW)) = > >>>> - start_eip & 0xf; > >>>> -} > >>>> - > >>>> -static inline void smpboot_restore_warm_reset_vector(void) > >>>> -{ > >>>> - unsigned long flags; > >>>> - > >>>> - /* > >>>> - * Paranoid: Set warm reset code and vector here back > >>>> - * to default values. > >>>> - */ > >>>> - spin_lock_irqsave(&rtc_lock, flags); > >>>> - CMOS_WRITE(0, 0xf); > >>>> - spin_unlock_irqrestore(&rtc_lock, flags); > >>>> - > >>>> - *((volatile u32 *)phys_to_virt(TRAMPOLINE_PHYS_LOW)) = 0; > >>>> -} > >>>> - > >>>> static void init_freq_invariance(void); > >>>> > >>>> /* > >>>> @@ -1049,20 +1020,6 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle, > >>>> * the targeted processor. > >>>> */ > >>>> > >>>> - if (x86_platform.legacy.warm_reset) { > >>>> - > >>>> - pr_debug("Setting warm reset code and vector.\n"); > >>>> - > >>>> - smpboot_setup_warm_reset_vector(start_ip); > >>>> - /* > >>>> - * Be paranoid about clearing APIC errors. > >>>> - */ > >>>> - if (APIC_INTEGRATED(boot_cpu_apic_version)) { > >>>> - apic_write(APIC_ESR, 0); > >>>> - apic_read(APIC_ESR); > >>>> - } > >>>> - } > >>>> - > >>>> /* > >>>> * AP might wait on cpu_callout_mask in cpu_init() with > >>>> * cpu_initialized_mask set if previous attempt to online > >>>> @@ -1118,13 +1075,6 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle, > >>>> } > >>>> } > >>>> > >>>> - if (x86_platform.legacy.warm_reset) { > >>>> - /* > >>>> - * Cleanup possible dangling ends... > >>>> - */ > >>>> - smpboot_restore_warm_reset_vector(); > >>>> - } > >>>> - > >>>> return boot_error; > >>>> } > >>> You removed x86_platform.legacy.warm_reset in the original patch, but > >>> that is missing in V2. > >> Second hunk? Or are you referring to something different? > > Removing the warm_reset field from struct x86_legacy_features. > > Ok, but that is still present as the 2nd hunk of the patch.
My apologies, Gmail was hiding that section of the patch because it was a reply to the original patch. For future reference, add the version number to the title when resubmitting a patch (ie. [PATCH v2]).
-- Brian Gerst
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