Messages in this thread | | | Subject | Re: [PATCH v2] x86/smpboot: Remove 486-isms from the modern AP boot path | From | Andrew Cooper <> | Date | Tue, 31 Mar 2020 23:44:51 +0100 |
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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?
~Andrew
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