Messages in this thread Patch in this message | | | From | Andrew Cooper <> | Subject | [PATCH v2] x86/smpboot: Remove 486-isms from the modern AP boot path | Date | Tue, 31 Mar 2020 18:58:10 +0100 |
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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; } -- 2.11.0
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