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88c9281a9f
The Hyper-V top-level functional specification states, that "algorithms should be resilient to sudden jumps forward or backward in the TSC value", this means that we should consider TSC as unstable. In some cases tsc tests are able to detect the instability, it was detected in 543 out of 646 boots in my testing: Measured 6277 cycles TSC warp between CPUs, turning off TSC clock. tsc: Marking TSC unstable due to check_tsc_sync_source failed This is, however, just a heuristic. On Hyper-V platform there are two good clocksources: MSR-based hyperv_clocksource and recently introduced TSC page. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: K. Y. Srinivasan <kys@microsoft.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: devel@linuxdriverproject.org Link: http://lkml.kernel.org/r/1440003264-9949-1-git-send-email-vkuznets@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
152 lines
3.7 KiB
C
152 lines
3.7 KiB
C
/*
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* HyperV Detection code.
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*
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* Copyright (C) 2010, Novell, Inc.
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* Author : K. Y. Srinivasan <ksrinivasan@novell.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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*/
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#include <linux/types.h>
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#include <linux/time.h>
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#include <linux/clocksource.h>
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#include <linux/module.h>
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#include <linux/hardirq.h>
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#include <linux/efi.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
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#include <asm/processor.h>
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#include <asm/hypervisor.h>
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#include <asm/hyperv.h>
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#include <asm/mshyperv.h>
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#include <asm/desc.h>
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#include <asm/idle.h>
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#include <asm/irq_regs.h>
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#include <asm/i8259.h>
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#include <asm/apic.h>
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#include <asm/timer.h>
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struct ms_hyperv_info ms_hyperv;
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EXPORT_SYMBOL_GPL(ms_hyperv);
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#if IS_ENABLED(CONFIG_HYPERV)
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static void (*vmbus_handler)(void);
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void hyperv_vector_handler(struct pt_regs *regs)
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{
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struct pt_regs *old_regs = set_irq_regs(regs);
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entering_irq();
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inc_irq_stat(irq_hv_callback_count);
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if (vmbus_handler)
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vmbus_handler();
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exiting_irq();
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set_irq_regs(old_regs);
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}
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void hv_setup_vmbus_irq(void (*handler)(void))
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{
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vmbus_handler = handler;
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/*
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* Setup the IDT for hypervisor callback. Prevent reallocation
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* at module reload.
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*/
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if (!test_bit(HYPERVISOR_CALLBACK_VECTOR, used_vectors))
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alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR,
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hyperv_callback_vector);
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}
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void hv_remove_vmbus_irq(void)
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{
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/* We have no way to deallocate the interrupt gate */
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vmbus_handler = NULL;
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}
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EXPORT_SYMBOL_GPL(hv_setup_vmbus_irq);
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EXPORT_SYMBOL_GPL(hv_remove_vmbus_irq);
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#endif
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static uint32_t __init ms_hyperv_platform(void)
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{
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u32 eax;
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u32 hyp_signature[3];
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if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
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return 0;
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cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
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&eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
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if (eax >= HYPERV_CPUID_MIN &&
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eax <= HYPERV_CPUID_MAX &&
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!memcmp("Microsoft Hv", hyp_signature, 12))
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return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS;
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return 0;
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}
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static cycle_t read_hv_clock(struct clocksource *arg)
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{
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cycle_t current_tick;
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/*
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* Read the partition counter to get the current tick count. This count
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* is set to 0 when the partition is created and is incremented in
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* 100 nanosecond units.
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*/
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rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
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return current_tick;
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}
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static struct clocksource hyperv_cs = {
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.name = "hyperv_clocksource",
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.rating = 400, /* use this when running on Hyperv*/
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.read = read_hv_clock,
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.mask = CLOCKSOURCE_MASK(64),
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.flags = CLOCK_SOURCE_IS_CONTINUOUS,
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};
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static void __init ms_hyperv_init_platform(void)
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{
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/*
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* Extract the features and hints
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*/
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ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
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ms_hyperv.hints = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
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printk(KERN_INFO "HyperV: features 0x%x, hints 0x%x\n",
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ms_hyperv.features, ms_hyperv.hints);
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#ifdef CONFIG_X86_LOCAL_APIC
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if (ms_hyperv.features & HV_X64_MSR_APIC_FREQUENCY_AVAILABLE) {
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/*
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* Get the APIC frequency.
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*/
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u64 hv_lapic_frequency;
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rdmsrl(HV_X64_MSR_APIC_FREQUENCY, hv_lapic_frequency);
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hv_lapic_frequency = div_u64(hv_lapic_frequency, HZ);
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lapic_timer_frequency = hv_lapic_frequency;
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printk(KERN_INFO "HyperV: LAPIC Timer Frequency: %#x\n",
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lapic_timer_frequency);
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}
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#endif
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if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
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clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
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#ifdef CONFIG_X86_IO_APIC
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no_timer_check = 1;
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#endif
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mark_tsc_unstable("running on Hyper-V");
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}
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const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
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.name = "Microsoft HyperV",
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.detect = ms_hyperv_platform,
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.init_platform = ms_hyperv_init_platform,
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};
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EXPORT_SYMBOL(x86_hyper_ms_hyperv);
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