linux/arch/x86/kernel/cpu/mshyperv.c
K. Y. Srinivasan e179f69141 x86, irq, pic: Probe for legacy PIC and set legacy_pic appropriately
The legacy PIC may or may not be available and we need a mechanism to
detect the existence of the legacy PIC that is applicable for all
hardware (both physical as well as virtual) currently supported by
Linux.

On Hyper-V, when our legacy firmware presented to the guests, emulates
the legacy PIC while when our EFI based firmware is presented we do
not emulate the PIC. To support Hyper-V EFI firmware, we had to set
the legacy_pic to the null_legacy_pic since we had to bypass PIC based
calibration in the early boot code. While, on the EFI firmware, we
know we don't emulate the legacy PIC, we need a generic mechanism to
detect the presence of the legacy PIC that is not based on boot time
state - this became apparent when we tried to get kexec to work on
Hyper-V EFI firmware.

This patch implements the proposal put forth by H. Peter Anvin
<hpa@linux.intel.com>: Write a known value to the PIC data port and
read it back. If the value read is the value written, we do have the
PIC, if not there is no PIC and we can safely set the legacy_pic to
null_legacy_pic. Since the read from an unconnected I/O port returns
0xff, we will use ~(1 << PIC_CASCADE_IR) (0xfb: mask all lines except
the cascade line) to probe for the existence of the PIC.

In version V1 of the patch, I had cleaned up the code based on comments from Peter.
In version V2 of the patch, I have addressed additional comments from Peter.
In version V3 of the patch, I have addressed Jan's comments (JBeulich@suse.com).
In version V4 of the patch, I have addressed additional comments from Peter.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Link: http://lkml.kernel.org/r/1397501029-29286-1-git-send-email-kys@microsoft.com
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-04-14 11:49:55 -07:00

153 lines
3.7 KiB
C

/*
* HyperV Detection code.
*
* Copyright (C) 2010, Novell, Inc.
* Author : K. Y. Srinivasan <ksrinivasan@novell.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
*/
#include <linux/types.h>
#include <linux/time.h>
#include <linux/clocksource.h>
#include <linux/module.h>
#include <linux/hardirq.h>
#include <linux/efi.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <asm/processor.h>
#include <asm/hypervisor.h>
#include <asm/hyperv.h>
#include <asm/mshyperv.h>
#include <asm/desc.h>
#include <asm/idle.h>
#include <asm/irq_regs.h>
#include <asm/i8259.h>
#include <asm/apic.h>
#include <asm/timer.h>
struct ms_hyperv_info ms_hyperv;
EXPORT_SYMBOL_GPL(ms_hyperv);
#if IS_ENABLED(CONFIG_HYPERV)
static void (*vmbus_handler)(void);
void hyperv_vector_handler(struct pt_regs *regs)
{
struct pt_regs *old_regs = set_irq_regs(regs);
irq_enter();
exit_idle();
inc_irq_stat(irq_hv_callback_count);
if (vmbus_handler)
vmbus_handler();
irq_exit();
set_irq_regs(old_regs);
}
void hv_setup_vmbus_irq(void (*handler)(void))
{
vmbus_handler = handler;
/*
* Setup the IDT for hypervisor callback. Prevent reallocation
* at module reload.
*/
if (!test_bit(HYPERVISOR_CALLBACK_VECTOR, used_vectors))
alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR,
hyperv_callback_vector);
}
void hv_remove_vmbus_irq(void)
{
/* We have no way to deallocate the interrupt gate */
vmbus_handler = NULL;
}
EXPORT_SYMBOL_GPL(hv_setup_vmbus_irq);
EXPORT_SYMBOL_GPL(hv_remove_vmbus_irq);
#endif
static uint32_t __init ms_hyperv_platform(void)
{
u32 eax;
u32 hyp_signature[3];
if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
return 0;
cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
&eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
if (eax >= HYPERV_CPUID_MIN &&
eax <= HYPERV_CPUID_MAX &&
!memcmp("Microsoft Hv", hyp_signature, 12))
return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS;
return 0;
}
static cycle_t read_hv_clock(struct clocksource *arg)
{
cycle_t current_tick;
/*
* Read the partition counter to get the current tick count. This count
* is set to 0 when the partition is created and is incremented in
* 100 nanosecond units.
*/
rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
return current_tick;
}
static struct clocksource hyperv_cs = {
.name = "hyperv_clocksource",
.rating = 400, /* use this when running on Hyperv*/
.read = read_hv_clock,
.mask = CLOCKSOURCE_MASK(64),
};
static void __init ms_hyperv_init_platform(void)
{
/*
* Extract the features and hints
*/
ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
ms_hyperv.hints = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
printk(KERN_INFO "HyperV: features 0x%x, hints 0x%x\n",
ms_hyperv.features, ms_hyperv.hints);
#ifdef CONFIG_X86_LOCAL_APIC
if (ms_hyperv.features & HV_X64_MSR_APIC_FREQUENCY_AVAILABLE) {
/*
* Get the APIC frequency.
*/
u64 hv_lapic_frequency;
rdmsrl(HV_X64_MSR_APIC_FREQUENCY, hv_lapic_frequency);
hv_lapic_frequency = div_u64(hv_lapic_frequency, HZ);
lapic_timer_frequency = hv_lapic_frequency;
printk(KERN_INFO "HyperV: LAPIC Timer Frequency: %#x\n",
lapic_timer_frequency);
}
#endif
if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
#ifdef CONFIG_X86_IO_APIC
no_timer_check = 1;
#endif
}
const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
.name = "Microsoft HyperV",
.detect = ms_hyperv_platform,
.init_platform = ms_hyperv_init_platform,
};
EXPORT_SYMBOL(x86_hyper_ms_hyperv);