From: Michael Kelley <mikel...@microsoft.com>

Add ARM64-specific code to enable Hyper-V. This code includes:
* Detecting Hyper-V and initializing the guest/Hyper-V interface
* Setting up Hyper-V's synthetic clocks
* Making hypercalls using the HVC instruction
* Setting up VMbus and stimer0 interrupts
* Setting up kexec and crash handlers
This code is architecture dependent code and is mostly driven by
architecture independent code in the VMbus driver in drivers/hv/hv.c
and drivers/hv/vmbus_drv.c.

This code is built only when CONFIG_HYPERV is enabled.

Signed-off-by: Michael Kelley <mikel...@microsoft.com>
Signed-off-by: K. Y. Srinivasan <k...@microsoft.com>
---
 MAINTAINERS                  |   1 +
 arch/arm64/Makefile          |   1 +
 arch/arm64/hyperv/Makefile   |   2 +
 arch/arm64/hyperv/hv_hvc.S   |  54 +++++
 arch/arm64/hyperv/hv_init.c  | 441 +++++++++++++++++++++++++++++++++++
 arch/arm64/hyperv/mshyperv.c | 178 ++++++++++++++
 6 files changed, 677 insertions(+)
 create mode 100644 arch/arm64/hyperv/Makefile
 create mode 100644 arch/arm64/hyperv/hv_hvc.S
 create mode 100644 arch/arm64/hyperv/hv_init.c
 create mode 100644 arch/arm64/hyperv/mshyperv.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 72f19cef4c48..326eeb32a0cd 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6837,6 +6837,7 @@ F:        arch/x86/kernel/cpu/mshyperv.c
 F:     arch/x86/hyperv
 F:     arch/arm64/include/asm/hyperv-tlfs.h
 F:     arch/arm64/include/asm/mshyperv.h
+F:     arch/arm64/hyperv
 F:     drivers/hid/hid-hyperv.c
 F:     drivers/hv/
 F:     drivers/input/serio/hyperv-keyboard.c
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 6cb9fc7e9382..ad9ec0579553 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -106,6 +106,7 @@ core-y              += arch/arm64/kernel/ arch/arm64/mm/
 core-$(CONFIG_NET) += arch/arm64/net/
 core-$(CONFIG_KVM) += arch/arm64/kvm/
 core-$(CONFIG_XEN) += arch/arm64/xen/
+core-$(CONFIG_HYPERV) += arch/arm64/hyperv/
 core-$(CONFIG_CRYPTO) += arch/arm64/crypto/
 libs-y         := arch/arm64/lib/ $(libs-y)
 core-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
diff --git a/arch/arm64/hyperv/Makefile b/arch/arm64/hyperv/Makefile
new file mode 100644
index 000000000000..988eda55330c
--- /dev/null
+++ b/arch/arm64/hyperv/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-y          := hv_init.o hv_hvc.o mshyperv.o
diff --git a/arch/arm64/hyperv/hv_hvc.S b/arch/arm64/hyperv/hv_hvc.S
new file mode 100644
index 000000000000..82636969b4f2
--- /dev/null
+++ b/arch/arm64/hyperv/hv_hvc.S
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Microsoft Hyper-V hypervisor invocation routines
+ *
+ * Copyright (C) 2018, Microsoft, Inc.
+ *
+ * Author : Michael Kelley <mikel...@microsoft.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ */
+
+#include <linux/linkage.h>
+
+       .text
+/*
+ * Do the HVC instruction.  For Hyper-V the argument is always 1.
+ * x0 contains the hypercall control value, while additional registers
+ * vary depending on the hypercall, and whether the hypercall arguments
+ * are in memory or in registers (a "fast" hypercall per the Hyper-V
+ * TLFS).  When the arguments are in memory x1 is the guest physical
+ * address of the input arguments, and x2 is the guest physical
+ * address of the output arguments.  When the arguments are in
+ * registers, the register values depends on the hypercall.  Note
+ * that this version cannot return any values in registers.
+ */
+ENTRY(hv_do_hvc)
+       hvc #1
+       ret
+ENDPROC(hv_do_hvc)
+
+/*
+ * This variant of HVC invocation is for hv_get_vpreg and
+ * hv_get_vpreg_128. The input parameters are passed in registers
+ * along with a pointer in x4 to where the output result should
+ * be stored. The output is returned in x15 and x16.  x18 is used as
+ * scratch space to avoid buildng a stack frame, as Hyper-V does
+ * not preserve registers x0-x17.
+ */
+ENTRY(hv_do_hvc_fast_get)
+       mov x18, x4
+       hvc #1
+       str x15,[x18]
+       str x16,[x18,#8]
+       ret
+ENDPROC(hv_do_hvc_fast_get)
diff --git a/arch/arm64/hyperv/hv_init.c b/arch/arm64/hyperv/hv_init.c
new file mode 100644
index 000000000000..aa1a8c09d989
--- /dev/null
+++ b/arch/arm64/hyperv/hv_init.c
@@ -0,0 +1,441 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Initialization of the interface with Microsoft's Hyper-V hypervisor,
+ * and various low level utility routines for interacting with Hyper-V.
+ *
+ * Copyright (C) 2018, Microsoft, Inc.
+ *
+ * Author : Michael Kelley <mikel...@microsoft.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ */
+
+
+#include <linux/types.h>
+#include <linux/version.h>
+#include <linux/export.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/clocksource.h>
+#include <linux/sched_clock.h>
+#include <linux/acpi.h>
+#include <linux/module.h>
+#include <linux/hyperv.h>
+#include <linux/slab.h>
+#include <linux/cpuhotplug.h>
+#include <linux/psci.h>
+#include <asm-generic/bug.h>
+#include <asm/hypervisor.h>
+#include <asm/hyperv-tlfs.h>
+#include <asm/mshyperv.h>
+#include <asm/sysreg.h>
+#include <clocksource/arm_arch_timer.h>
+
+static bool    hyperv_initialized;
+struct         ms_hyperv_info ms_hyperv;
+EXPORT_SYMBOL_GPL(ms_hyperv);
+
+static struct ms_hyperv_tsc_page *tsc_pg;
+
+struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
+{
+       return tsc_pg;
+}
+EXPORT_SYMBOL_GPL(hv_get_tsc_page);
+
+static u64 read_hv_sched_clock_tsc(void)
+{
+       u64 current_tick = hv_read_tsc_page(tsc_pg);
+
+       if (current_tick == U64_MAX)
+               current_tick = hv_get_vpreg(HV_REGISTER_TIME_REFCOUNT);
+
+       return current_tick;
+}
+
+static u64 read_hv_clock_tsc(struct clocksource *arg)
+{
+       u64 current_tick = hv_read_tsc_page(tsc_pg);
+
+       if (current_tick == U64_MAX)
+               current_tick = hv_get_vpreg(HV_REGISTER_TIME_REFCOUNT);
+
+       return current_tick;
+}
+
+static struct clocksource hyperv_cs_tsc = {
+               .name           = "hyperv_clocksource_tsc_page",
+               .rating         = 400,
+               .read           = read_hv_clock_tsc,
+               .mask           = CLOCKSOURCE_MASK(64),
+               .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static u64 read_hv_sched_clock_msr(void)
+{
+       return hv_get_vpreg(HV_REGISTER_TIME_REFCOUNT);
+}
+
+static u64 read_hv_clock_msr(struct clocksource *arg)
+{
+       return hv_get_vpreg(HV_REGISTER_TIME_REFCOUNT);
+}
+
+static struct clocksource hyperv_cs_msr = {
+       .name           = "hyperv_clocksource_msr",
+       .rating         = 400,
+       .read           = read_hv_clock_msr,
+       .mask           = CLOCKSOURCE_MASK(64),
+       .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+struct clocksource *hyperv_cs;
+EXPORT_SYMBOL_GPL(hyperv_cs);
+
+u32 *hv_vp_index;
+EXPORT_SYMBOL_GPL(hv_vp_index);
+
+u32 hv_max_vp_index;
+
+static int hv_cpu_init(unsigned int cpu)
+{
+       u64 msr_vp_index;
+
+       hv_get_vp_index(msr_vp_index);
+
+       hv_vp_index[smp_processor_id()] = msr_vp_index;
+
+       if (msr_vp_index > hv_max_vp_index)
+               hv_max_vp_index = msr_vp_index;
+
+       return 0;
+}
+
+/*
+ * This function is invoked via the ACPI clocksource probe mechanism. We
+ * don't actually use any values from the ACPI GTDT table, but we set up
+ * the Hyper-V synthetic clocksource and do other initialization for
+ * interacting with Hyper-V the first time.  Using early_initcall to invoke
+ * this function is too late because interrupts are already enabled at that
+ * point, and sched_clock_register must run before interrupts are enabled.
+ *
+ * 1. Setup the guest ID.
+ * 2. Get features and hints info from Hyper-V
+ * 3. Setup per-cpu VP indices.
+ * 4. Register Hyper-V specific clocksource.
+ * 5. Register the scheduler clock.
+ */
+
+static int __init hyperv_init(struct acpi_table_header *table)
+{
+       struct hv_get_vp_register_output result;
+       u32     a, b, c, d;
+       u64     guest_id;
+       int     i;
+
+       /*
+        * If we're in a VM on Hyper-V, the ACPI hypervisor_id field will
+        * have the string "MsHyperV".
+        */
+       if (strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8))
+               return 1;
+
+       /* Setup the guest ID */
+       guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
+       hv_set_vpreg(HV_REGISTER_GUEST_OSID, guest_id);
+
+       /* Get the features and hints from Hyper-V */
+       hv_get_vpreg_128(HV_REGISTER_PRIVILEGES_AND_FEATURES, &result);
+       ms_hyperv.features = lower_32_bits(result.registervaluelow);
+       ms_hyperv.misc_features = upper_32_bits(result.registervaluehigh);
+
+       hv_get_vpreg_128(HV_REGISTER_FEATURES, &result);
+       ms_hyperv.hints = lower_32_bits(result.registervaluelow);
+
+       pr_info("Hyper-V: Features 0x%x, hints 0x%x\n",
+               ms_hyperv.features, ms_hyperv.hints);
+
+       /*
+        * Direct mode is the only option for STIMERs provided Hyper-V
+        * on ARM64, so Hyper-V doesn't actually set the flag.  But add the
+        * flag so the architecture independent code in drivers/hv/hv.c
+        * will correctly use that mode.
+        */
+       ms_hyperv.misc_features |= HV_STIMER_DIRECT_MODE_AVAILABLE;
+
+       /*
+        * Hyper-V on ARM64 doesn't support AutoEOI.  Add the hint
+        * that tells architecture independent code not to use this
+        * feature.
+        */
+       ms_hyperv.hints |= HV_DEPRECATING_AEOI_RECOMMENDED;
+
+       /* Get information about the Hyper-V host version */
+       hv_get_vpreg_128(HV_REGISTER_HYPERVISOR_VERSION, &result);
+       a = lower_32_bits(result.registervaluelow);
+       b = upper_32_bits(result.registervaluelow);
+       c = lower_32_bits(result.registervaluehigh);
+       d = upper_32_bits(result.registervaluehigh);
+       pr_info("Hyper-V: Host Build %d.%d.%d.%d-%d-%d\n",
+               b >> 16, b & 0xFFFF, a, d & 0xFFFFFF, c, d >> 24);
+
+       /* Allocate percpu VP index */
+       hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
+                                   GFP_KERNEL);
+       if (!hv_vp_index)
+               return 1;
+
+       for (i = 0; i < num_possible_cpus(); i++)
+               hv_vp_index[i] = VP_INVAL;
+
+       if (cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "arm64/hyperv_init:online",
+                             hv_cpu_init, NULL) < 0)
+               goto free_vp_index;
+
+       /*
+        * Try to set up what Hyper-V calls the "TSC reference page", which
+        * uses the ARM Generic Timer virtual counter with some scaling
+        * information to provide a fast and stable guest VM clocksource.
+        * If the TSC reference page can't be set up, fall back to reading
+        * the guest clock provided by Hyper-V's synthetic reference time
+        * register.
+        */
+       if (ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE) {
+
+               u64             tsc_msr;
+               phys_addr_t     phys_addr;
+
+               tsc_pg = __vmalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
+               if (tsc_pg) {
+                       phys_addr = page_to_phys(vmalloc_to_page(tsc_pg));
+                       tsc_msr = hv_get_vpreg(HV_REGISTER_REFERENCE_TSC);
+                       tsc_msr &= GENMASK_ULL(11, 0);
+                       tsc_msr = tsc_msr | 0x1 | (u64)phys_addr;
+                       hv_set_vpreg(HV_REGISTER_REFERENCE_TSC, tsc_msr);
+                       hyperv_cs = &hyperv_cs_tsc;
+                       sched_clock_register(read_hv_sched_clock_tsc,
+                                               64, HV_CLOCK_HZ);
+               }
+       }
+
+       if (!hyperv_cs &&
+           (ms_hyperv.features & HV_MSR_TIME_REF_COUNT_AVAILABLE)) {
+               hyperv_cs = &hyperv_cs_msr;
+               sched_clock_register(read_hv_sched_clock_msr,
+                                               64, HV_CLOCK_HZ);
+       }
+
+       if (hyperv_cs) {
+               hyperv_cs->archdata.vdso_direct = false;
+               clocksource_register_hz(hyperv_cs, HV_CLOCK_HZ);
+       }
+
+       hyperv_initialized = true;
+       return 0;
+
+free_vp_index:
+       kfree(hv_vp_index);
+       hv_vp_index = NULL;
+       return 1;
+}
+TIMER_ACPI_DECLARE(hyperv, ACPI_SIG_GTDT, hyperv_init);
+
+/*
+ * This routine is called before kexec/kdump, it does the required cleanup.
+ */
+void hyperv_cleanup(void)
+{
+       /* Reset our OS id */
+       hv_set_vpreg(HV_REGISTER_GUEST_OSID, 0);
+
+}
+EXPORT_SYMBOL_GPL(hyperv_cleanup);
+
+/*
+ * hv_do_hypercall- Invoke the specified hypercall
+ */
+u64 hv_do_hypercall(u64 control, void *input, void *output)
+{
+       u64 input_address;
+       u64 output_address;
+
+       input_address = input ? virt_to_phys(input) : 0;
+       output_address = output ? virt_to_phys(output) : 0;
+       return hv_do_hvc(control, input_address, output_address);
+}
+EXPORT_SYMBOL_GPL(hv_do_hypercall);
+
+/*
+ * hv_do_fast_hypercall8 -- Invoke the specified hypercall
+ * with arguments in registers instead of physical memory.
+ * Avoids the overhead of virt_to_phys for simple hypercalls.
+ */
+
+u64 hv_do_fast_hypercall8(u16 code, u64 input)
+{
+       u64 control;
+
+       control = (u64)code | HV_HYPERCALL_FAST_BIT;
+       return hv_do_hvc(control, input);
+}
+EXPORT_SYMBOL_GPL(hv_do_fast_hypercall8);
+
+
+/*
+ * Set a single VP register to a 64-bit value.
+ */
+void hv_set_vpreg(u32 msr, u64 value)
+{
+       union hv_hypercall_status status;
+
+       status.as_uint64 = hv_do_hvc(
+               HVCALL_SET_VP_REGISTERS | HV_HYPERCALL_FAST_BIT |
+                       HV_HYPERCALL_REP_COUNT_1,
+               HV_PARTITION_ID_SELF,
+               HV_VP_INDEX_SELF,
+               msr,
+               0,
+               value,
+               0);
+
+       /*
+        * Something is fundamentally broken in the hypervisor if
+        * setting a VP register fails. There's really no way to
+        * continue as a guest VM, so panic.
+        */
+       BUG_ON(status.status != HV_STATUS_SUCCESS);
+}
+EXPORT_SYMBOL_GPL(hv_set_vpreg);
+
+
+/*
+ * Get the value of a single VP register, and only the low order 64 bits.
+ */
+u64 hv_get_vpreg(u32 msr)
+{
+       union hv_hypercall_status status;
+       struct hv_get_vp_register_output output;
+
+       status.as_uint64 = hv_do_hvc_fast_get(
+               HVCALL_GET_VP_REGISTERS | HV_HYPERCALL_FAST_BIT |
+                       HV_HYPERCALL_REP_COUNT_1,
+               HV_PARTITION_ID_SELF,
+               HV_VP_INDEX_SELF,
+               msr,
+               &output);
+
+       /*
+        * Something is fundamentally broken in the hypervisor if
+        * getting a VP register fails. There's really no way to
+        * continue as a guest VM, so panic.
+        */
+       BUG_ON(status.status != HV_STATUS_SUCCESS);
+
+       return output.registervaluelow;
+}
+EXPORT_SYMBOL_GPL(hv_get_vpreg);
+
+/*
+ * Get the value of a single VP register that is 128 bits in size.  This is a
+ * separate call in order to avoid complicating the calling sequence for
+ * the much more frequently used 64-bit version.
+ */
+void hv_get_vpreg_128(u32 msr, struct hv_get_vp_register_output *result)
+{
+       union hv_hypercall_status status;
+
+       status.as_uint64 = hv_do_hvc_fast_get(
+               HVCALL_GET_VP_REGISTERS | HV_HYPERCALL_FAST_BIT |
+                       HV_HYPERCALL_REP_COUNT_1,
+               HV_PARTITION_ID_SELF,
+               HV_VP_INDEX_SELF,
+               msr,
+               result);
+
+       /*
+        * Something is fundamentally broken in the hypervisor if
+        * getting a VP register fails. There's really no way to
+        * continue as a guest VM, so panic.
+        */
+       BUG_ON(status.status != HV_STATUS_SUCCESS);
+
+       return;
+
+}
+EXPORT_SYMBOL_GPL(hv_get_vpreg_128);
+
+void hyperv_report_panic(struct pt_regs *regs, long err)
+{
+       static bool panic_reported;
+       u64 guest_id;
+
+       /*
+        * We prefer to report panic on 'die' chain as we have proper
+        * registers to report, but if we miss it (e.g. on BUG()) we need
+        * to report it on 'panic'.
+        */
+       if (panic_reported)
+               return;
+       panic_reported = true;
+
+       guest_id = hv_get_vpreg(HV_REGISTER_GUEST_OSID);
+
+       /*
+        * Hyper-V provides the ability to store only 5 values.
+        * Pick the passed in error value, the guest_id, and the PC.
+        * The first two general registers are added arbitrarily.
+        */
+       hv_set_vpreg(HV_REGISTER_CRASH_P0, err);
+       hv_set_vpreg(HV_REGISTER_CRASH_P1, guest_id);
+       hv_set_vpreg(HV_REGISTER_CRASH_P2, regs->pc);
+       hv_set_vpreg(HV_REGISTER_CRASH_P3, regs->regs[0]);
+       hv_set_vpreg(HV_REGISTER_CRASH_P4, regs->regs[1]);
+
+       /*
+        * Let Hyper-V know there is crash data available
+        */
+       hv_set_vpreg(HV_REGISTER_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
+}
+EXPORT_SYMBOL_GPL(hyperv_report_panic);
+
+/*
+ * hyperv_report_panic_msg - report panic message to Hyper-V
+ * @pa: physical address of the panic page containing the message
+ * @size: size of the message in the page
+ */
+void hyperv_report_panic_msg(phys_addr_t pa, size_t size)
+{
+       /*
+        * P3 to contain the physical address of the panic page & P4 to
+        * contain the size of the panic data in that page. Rest of the
+        * registers are no-op when the NOTIFY_MSG flag is set.
+        */
+       hv_set_vpreg(HV_REGISTER_CRASH_P0, 0);
+       hv_set_vpreg(HV_REGISTER_CRASH_P1, 0);
+       hv_set_vpreg(HV_REGISTER_CRASH_P2, 0);
+       hv_set_vpreg(HV_REGISTER_CRASH_P3, pa);
+       hv_set_vpreg(HV_REGISTER_CRASH_P4, size);
+
+       /*
+        * Let Hyper-V know there is crash data available along with
+        * the panic message.
+        */
+       hv_set_vpreg(HV_REGISTER_CRASH_CTL,
+              (HV_CRASH_CTL_CRASH_NOTIFY | HV_CRASH_CTL_CRASH_NOTIFY_MSG));
+}
+EXPORT_SYMBOL_GPL(hyperv_report_panic_msg);
+
+bool hv_is_hyperv_initialized(void)
+{
+       return hyperv_initialized;
+}
+EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);
diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
new file mode 100644
index 000000000000..3ef055599412
--- /dev/null
+++ b/arch/arm64/hyperv/mshyperv.c
@@ -0,0 +1,178 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Core routines for interacting with Microsoft's Hyper-V hypervisor,
+ * including setting up VMbus and STIMER interrupts, and handling
+ * crashes and kexecs. These interactions are through a set of
+ * static "handler" variables set by the architecture independent
+ * VMbus and STIMER drivers.  This design is used to meet x86/x64
+ * requirements for avoiding direct linkages and allowing the VMbus
+ * and STIMER drivers to be unloaded and reloaded.
+ *
+ * Copyright (C) 2018, Microsoft, Inc.
+ *
+ * Author : Michael Kelley <mikel...@microsoft.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ */
+
+#include <linux/types.h>
+#include <linux/export.h>
+#include <linux/interrupt.h>
+#include <linux/kexec.h>
+#include <linux/acpi.h>
+#include <linux/ptrace.h>
+#include <asm/hyperv-tlfs.h>
+#include <asm/mshyperv.h>
+
+static void (*vmbus_handler)(void);
+static void (*hv_stimer0_handler)(void);
+static void (*hv_kexec_handler)(void);
+static void (*hv_crash_handler)(struct pt_regs *regs);
+
+static int vmbus_irq;
+static long __percpu *vmbus_evt;
+static long __percpu *stimer0_evt;
+
+irqreturn_t hyperv_vector_handler(int irq, void *dev_id)
+{
+       if (vmbus_handler)
+               vmbus_handler();
+       return IRQ_HANDLED;
+}
+
+/* Must be done just once */
+void hv_setup_vmbus_irq(void (*handler)(void))
+{
+       int result;
+
+       vmbus_handler = handler;
+       vmbus_irq = acpi_register_gsi(NULL, HYPERVISOR_CALLBACK_VECTOR,
+                                ACPI_LEVEL_SENSITIVE, ACPI_ACTIVE_HIGH);
+       if (vmbus_irq <= 0) {
+               pr_err("Can't register Hyper-V VMBus GSI. Error %d",
+                       vmbus_irq);
+               vmbus_irq = 0;
+               return;
+       }
+       vmbus_evt = alloc_percpu(long);
+       result = request_percpu_irq(vmbus_irq, hyperv_vector_handler,
+                       "Hyper-V VMbus", vmbus_evt);
+       if (result) {
+               pr_err("Can't request Hyper-V VMBus IRQ %d. Error %d",
+                       vmbus_irq, result);
+               free_percpu(vmbus_evt);
+               acpi_unregister_gsi(vmbus_irq);
+               vmbus_irq = 0;
+       }
+}
+EXPORT_SYMBOL_GPL(hv_setup_vmbus_irq);
+
+/* Must be done just once */
+void hv_remove_vmbus_irq(void)
+{
+       if (vmbus_irq) {
+               free_percpu_irq(vmbus_irq, vmbus_evt);
+               free_percpu(vmbus_evt);
+               acpi_unregister_gsi(vmbus_irq);
+       }
+}
+EXPORT_SYMBOL_GPL(hv_remove_vmbus_irq);
+
+/* Must be done by each CPU */
+void hv_enable_vmbus_irq(void)
+{
+       enable_percpu_irq(vmbus_irq, 0);
+}
+EXPORT_SYMBOL_GPL(hv_enable_vmbus_irq);
+
+/* Must be done by each CPU */
+void hv_disable_vmbus_irq(void)
+{
+       disable_percpu_irq(vmbus_irq);
+}
+EXPORT_SYMBOL_GPL(hv_disable_vmbus_irq);
+
+/* Routines to do per-architecture handling of STIMER0 when in Direct Mode */
+
+static irqreturn_t hv_stimer0_vector_handler(int irq, void *dev_id)
+{
+       if (hv_stimer0_handler)
+               hv_stimer0_handler();
+       return IRQ_HANDLED;
+}
+
+int hv_setup_stimer0_irq(int *irq, int *vector, void (*handler)(void))
+{
+       int localirq;
+       int result;
+
+       localirq = acpi_register_gsi(NULL, HV_STIMER0_IRQNR,
+                       ACPI_LEVEL_SENSITIVE, ACPI_ACTIVE_HIGH);
+       if (localirq <= 0) {
+               pr_err("Can't register Hyper-V stimer0 GSI. Error %d",
+                       localirq);
+               *irq = 0;
+               return -1;
+       }
+       stimer0_evt = alloc_percpu(long);
+       result = request_percpu_irq(localirq, hv_stimer0_vector_handler,
+                                        "Hyper-V stimer0", stimer0_evt);
+       if (result) {
+               pr_err("Can't request Hyper-V stimer0 IRQ %d. Error %d",
+                       localirq, result);
+               free_percpu(stimer0_evt);
+               acpi_unregister_gsi(localirq);
+               *irq = 0;
+               return -1;
+       }
+
+       hv_stimer0_handler = handler;
+       *vector = HV_STIMER0_IRQNR;
+       *irq = localirq;
+       return 0;
+}
+EXPORT_SYMBOL_GPL(hv_setup_stimer0_irq);
+
+void hv_remove_stimer0_irq(int irq)
+{
+       hv_stimer0_handler = NULL;
+       if (irq) {
+               free_percpu_irq(irq, stimer0_evt);
+               free_percpu(stimer0_evt);
+               acpi_unregister_gsi(irq);
+       }
+}
+EXPORT_SYMBOL_GPL(hv_remove_stimer0_irq);
+
+void hv_setup_kexec_handler(void (*handler)(void))
+{
+       hv_kexec_handler = handler;
+}
+EXPORT_SYMBOL_GPL(hv_setup_kexec_handler);
+
+void hv_remove_kexec_handler(void)
+{
+       hv_kexec_handler = NULL;
+}
+EXPORT_SYMBOL_GPL(hv_remove_kexec_handler);
+
+void hv_setup_crash_handler(void (*handler)(struct pt_regs *regs))
+{
+       hv_crash_handler = handler;
+}
+EXPORT_SYMBOL_GPL(hv_setup_crash_handler);
+
+void hv_remove_crash_handler(void)
+{
+       hv_crash_handler = NULL;
+}
+EXPORT_SYMBOL_GPL(hv_remove_crash_handler);
-- 
2.19.1

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