6 files changed, 368 insertions, 72 deletions

diff --git a/arch/x86/hyperv/Makefile b/arch/x86/hyperv/Makefile
index 367a8203cfcf..b173d404e3df 100644
--- a/arch/x86/hyperv/Makefile
+++ b/arch/x86/hyperv/Makefile
@@ -1 +1,2 @@
-obj-y           := hv_init.o mmu.o
+obj-y                   := hv_init.o mmu.o
+obj-$(CONFIG_X86_64)    += hv_apic.o
diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c
new file mode 100644
index 000000000000..f68855499391
--- /dev/null
+++ b/arch/x86/hyperv/hv_apic.c
@@ -0,0 +1,256 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Hyper-V specific APIC code.
+ *
+ * Copyright (C) 2018, Microsoft, Inc.
+ *
+ * Author : K. Y. Srinivasan <kys@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/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/clockchips.h>
+#include <linux/hyperv.h>
+#include <linux/slab.h>
+#include <linux/cpuhotplug.h>
+#include <asm/hypervisor.h>
+#include <asm/mshyperv.h>
+#include <asm/apic.h>
+
+static struct apic orig_apic;
+
+static u64 hv_apic_icr_read(void)
+{
+        u64 reg_val;
+
+        rdmsrl(HV_X64_MSR_ICR, reg_val);
+        return reg_val;
+}
+
+static void hv_apic_icr_write(u32 low, u32 id)
+{
+        u64 reg_val;
+
+        reg_val = SET_APIC_DEST_FIELD(id);
+        reg_val = reg_val << 32;
+        reg_val |= low;
+
+        wrmsrl(HV_X64_MSR_ICR, reg_val);
+}
+
+static u32 hv_apic_read(u32 reg)
+{
+        u32 reg_val, hi;
+
+        switch (reg) {
+        case APIC_EOI:
+                rdmsr(HV_X64_MSR_EOI, reg_val, hi);
+                return reg_val;
+        case APIC_TASKPRI:
+                rdmsr(HV_X64_MSR_TPR, reg_val, hi);
+                return reg_val;
+
+        default:
+                return native_apic_mem_read(reg);
+        }
+}
+
+static void hv_apic_write(u32 reg, u32 val)
+{
+        switch (reg) {
+        case APIC_EOI:
+                wrmsr(HV_X64_MSR_EOI, val, 0);
+                break;
+        case APIC_TASKPRI:
+                wrmsr(HV_X64_MSR_TPR, val, 0);
+                break;
+        default:
+                native_apic_mem_write(reg, val);
+        }
+}
+
+static void hv_apic_eoi_write(u32 reg, u32 val)
+{
+        wrmsr(HV_X64_MSR_EOI, val, 0);
+}
+
+/*
+ * IPI implementation on Hyper-V.
+ */
+static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector)
+{
+        struct ipi_arg_ex **arg;
+        struct ipi_arg_ex *ipi_arg;
+        unsigned long flags;
+        int nr_bank = 0;
+        int ret = 1;
+
+        local_irq_save(flags);
+        arg = (struct ipi_arg_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
+
+        ipi_arg = *arg;
+        if (unlikely(!ipi_arg))
+                goto ipi_mask_ex_done;
+
+        ipi_arg->vector = vector;
+        ipi_arg->reserved = 0;
+        ipi_arg->vp_set.valid_bank_mask = 0;
+
+        if (!cpumask_equal(mask, cpu_present_mask)) {
+                ipi_arg->vp_set.format = HV_GENERIC_SET_SPARSE_4K;
+                nr_bank = cpumask_to_vpset(&(ipi_arg->vp_set), mask);
+        }
+        if (!nr_bank)
+                ipi_arg->vp_set.format = HV_GENERIC_SET_ALL;
+
+        ret = hv_do_rep_hypercall(HVCALL_SEND_IPI_EX, 0, nr_bank,
+                              ipi_arg, NULL);
+
+ipi_mask_ex_done:
+        local_irq_restore(flags);
+        return ((ret == 0) ? true : false);
+}
+
+static bool __send_ipi_mask(const struct cpumask *mask, int vector)
+{
+        int cur_cpu, vcpu;
+        struct ipi_arg_non_ex **arg;
+        struct ipi_arg_non_ex *ipi_arg;
+        int ret = 1;
+        unsigned long flags;
+
+        if (cpumask_empty(mask))
+                return true;
+
+        if (!hv_hypercall_pg)
+                return false;
+
+        if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR))
+                return false;
+
+        if ((ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))
+                return __send_ipi_mask_ex(mask, vector);
+
+        local_irq_save(flags);
+        arg = (struct ipi_arg_non_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
+
+        ipi_arg = *arg;
+        if (unlikely(!ipi_arg))
+                goto ipi_mask_done;
+
+        ipi_arg->vector = vector;
+        ipi_arg->reserved = 0;
+        ipi_arg->cpu_mask = 0;
+
+        for_each_cpu(cur_cpu, mask) {
+                vcpu = hv_cpu_number_to_vp_number(cur_cpu);
+                /*
+                 * This particular version of the IPI hypercall can
+                 * only target upto 64 CPUs.
+                 */
+                if (vcpu >= 64)
+                        goto ipi_mask_done;
+
+                __set_bit(vcpu, (unsigned long *)&ipi_arg->cpu_mask);
+        }
+
+        ret = hv_do_hypercall(HVCALL_SEND_IPI, ipi_arg, NULL);
+
+ipi_mask_done:
+        local_irq_restore(flags);
+        return ((ret == 0) ? true : false);
+}
+
+static bool __send_ipi_one(int cpu, int vector)
+{
+        struct cpumask mask = CPU_MASK_NONE;
+
+        cpumask_set_cpu(cpu, &mask);
+        return __send_ipi_mask(&mask, vector);
+}
+
+static void hv_send_ipi(int cpu, int vector)
+{
+        if (!__send_ipi_one(cpu, vector))
+                orig_apic.send_IPI(cpu, vector);
+}
+
+static void hv_send_ipi_mask(const struct cpumask *mask, int vector)
+{
+        if (!__send_ipi_mask(mask, vector))
+                orig_apic.send_IPI_mask(mask, vector);
+}
+
+static void hv_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
+{
+        unsigned int this_cpu = smp_processor_id();
+        struct cpumask new_mask;
+        const struct cpumask *local_mask;
+
+        cpumask_copy(&new_mask, mask);
+        cpumask_clear_cpu(this_cpu, &new_mask);
+        local_mask = &new_mask;
+        if (!__send_ipi_mask(local_mask, vector))
+                orig_apic.send_IPI_mask_allbutself(mask, vector);
+}
+
+static void hv_send_ipi_allbutself(int vector)
+{
+        hv_send_ipi_mask_allbutself(cpu_online_mask, vector);
+}
+
+static void hv_send_ipi_all(int vector)
+{
+        if (!__send_ipi_mask(cpu_online_mask, vector))
+                orig_apic.send_IPI_all(vector);
+}
+
+static void hv_send_ipi_self(int vector)
+{
+        if (!__send_ipi_one(smp_processor_id(), vector))
+                orig_apic.send_IPI_self(vector);
+}
+
+void __init hv_apic_init(void)
+{
+        if (ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) {
+                if ((ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))
+                        pr_info("Hyper-V: Using ext hypercalls for IPI\n");
+                else
+                        pr_info("Hyper-V: Using IPI hypercalls\n");
+                /*
+                 * Set the IPI entry points.
+                 */
+                orig_apic = *apic;
+
+                apic->send_IPI = hv_send_ipi;
+                apic->send_IPI_mask = hv_send_ipi_mask;
+                apic->send_IPI_mask_allbutself = hv_send_ipi_mask_allbutself;
+                apic->send_IPI_allbutself = hv_send_ipi_allbutself;
+                apic->send_IPI_all = hv_send_ipi_all;
+                apic->send_IPI_self = hv_send_ipi_self;
+        }
+
+        if (ms_hyperv.hints & HV_X64_APIC_ACCESS_RECOMMENDED) {
+                pr_info("Hyper-V: Using MSR based APIC access\n");
+                apic_set_eoi_write(hv_apic_eoi_write);
+                apic->read      = hv_apic_read;
+                apic->write     = hv_apic_write;
+                apic->icr_write = hv_apic_icr_write;
+                apic->icr_read  = hv_apic_icr_read;
+        }
+}
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index cfecc2272f2d..4c431e1c1eff 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -91,12 +91,19 @@ EXPORT_SYMBOL_GPL(hv_vp_index);
 struct hv_vp_assist_page **hv_vp_assist_page;
 EXPORT_SYMBOL_GPL(hv_vp_assist_page);
 
+void  __percpu **hyperv_pcpu_input_arg;
+EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
+
 u32 hv_max_vp_index;
 
 static int hv_cpu_init(unsigned int cpu)
 {
         u64 msr_vp_index;
         struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
+        void **input_arg;
+
+        input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
+        *input_arg = page_address(alloc_page(GFP_KERNEL));
 
         hv_get_vp_index(msr_vp_index);
 
@@ -217,6 +224,16 @@ static int hv_cpu_die(unsigned int cpu)
 {
         struct hv_reenlightenment_control re_ctrl;
         unsigned int new_cpu;
+        unsigned long flags;
+        void **input_arg;
+        void *input_pg = NULL;
+
+        local_irq_save(flags);
+        input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
+        input_pg = *input_arg;
+        *input_arg = NULL;
+        local_irq_restore(flags);
+        free_page((unsigned long)input_pg);
 
         if (hv_vp_assist_page && hv_vp_assist_page[cpu])
                 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
@@ -242,8 +259,9 @@ static int hv_cpu_die(unsigned int cpu)
  *
  * 1. Setup the hypercall page.
  * 2. Register Hyper-V specific clocksource.
+ * 3. Setup Hyper-V specific APIC entry points.
  */
-void hyperv_init(void)
+void __init hyperv_init(void)
 {
         u64 guest_id, required_msrs;
         union hv_x64_msr_hypercall_contents hypercall_msr;
@@ -259,6 +277,16 @@ void hyperv_init(void)
         if ((ms_hyperv.features & required_msrs) != required_msrs)
                 return;
 
+        /*
+         * Allocate the per-CPU state for the hypercall input arg.
+         * If this allocation fails, we will not be able to setup
+         * (per-CPU) hypercall input page and thus this failure is
+         * fatal on Hyper-V.
+         */
+        hyperv_pcpu_input_arg = alloc_percpu(void  *);
+
+        BUG_ON(hyperv_pcpu_input_arg == NULL);
+
         /* Allocate percpu VP index */
         hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
                                     GFP_KERNEL);
@@ -296,7 +324,7 @@ void hyperv_init(void)
         hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 
-        hyper_alloc_mmu();
+        hv_apic_init();
 
         /*
          * Register Hyper-V specific clocksource.
diff --git a/arch/x86/hyperv/mmu.c b/arch/x86/hyperv/mmu.c
index 56c9ebac946f..5f053d7d1bd9 100644
--- a/arch/x86/hyperv/mmu.c
+++ b/arch/x86/hyperv/mmu.c
@@ -25,20 +25,13 @@ struct hv_flush_pcpu {
 struct hv_flush_pcpu_ex {
         u64 address_space;
         u64 flags;
-        struct {
-                u64 format;
-                u64 valid_bank_mask;
-                u64 bank_contents[];
-        } hv_vp_set;
+        struct hv_vpset hv_vp_set;
         u64 gva_list[];
 };
 
 /* Each gva in gva_list encodes up to 4096 pages to flush */
 #define HV_TLB_FLUSH_UNIT (4096 * PAGE_SIZE)
 
-static struct hv_flush_pcpu __percpu **pcpu_flush;
-
-static struct hv_flush_pcpu_ex __percpu **pcpu_flush_ex;
 
 /*
  * Fills in gva_list starting from offset. Returns the number of items added.
@@ -70,41 +63,6 @@ static inline int fill_gva_list(u64 gva_list[], int offset,
         return gva_n - offset;
 }
 
-/* Return the number of banks in the resulting vp_set */
-static inline int cpumask_to_vp_set(struct hv_flush_pcpu_ex *flush,
-                                    const struct cpumask *cpus)
-{
-        int cpu, vcpu, vcpu_bank, vcpu_offset, nr_bank = 1;
-
-        /* valid_bank_mask can represent up to 64 banks */
-        if (hv_max_vp_index / 64 >= 64)
-                return 0;
-
-        /*
-         * Clear all banks up to the maximum possible bank as hv_flush_pcpu_ex
-         * structs are not cleared between calls, we risk flushing unneeded
-         * vCPUs otherwise.
-         */
-        for (vcpu_bank = 0; vcpu_bank <= hv_max_vp_index / 64; vcpu_bank++)
-                flush->hv_vp_set.bank_contents[vcpu_bank] = 0;
-
-        /*
-         * Some banks may end up being empty but this is acceptable.
-         */
-        for_each_cpu(cpu, cpus) {
-                vcpu = hv_cpu_number_to_vp_number(cpu);
-                vcpu_bank = vcpu / 64;
-                vcpu_offset = vcpu % 64;
-                __set_bit(vcpu_offset, (unsigned long *)
-                          &flush->hv_vp_set.bank_contents[vcpu_bank]);
-                if (vcpu_bank >= nr_bank)
-                        nr_bank = vcpu_bank + 1;
-        }
-        flush->hv_vp_set.valid_bank_mask = GENMASK_ULL(nr_bank - 1, 0);
-
-        return nr_bank;
-}
-
 static void hyperv_flush_tlb_others(const struct cpumask *cpus,
                                     const struct flush_tlb_info *info)
 {
@@ -116,7 +74,7 @@ static void hyperv_flush_tlb_others(const struct cpumask *cpus,
 
         trace_hyperv_mmu_flush_tlb_others(cpus, info);
 
-        if (!pcpu_flush || !hv_hypercall_pg)
+        if (!hv_hypercall_pg)
                 goto do_native;
 
         if (cpumask_empty(cpus))
@@ -124,10 +82,8 @@ static void hyperv_flush_tlb_others(const struct cpumask *cpus,
 
         local_irq_save(flags);
 
-        flush_pcpu = this_cpu_ptr(pcpu_flush);
-
-        if (unlikely(!*flush_pcpu))
-                *flush_pcpu = page_address(alloc_page(GFP_ATOMIC));
+        flush_pcpu = (struct hv_flush_pcpu **)
+                     this_cpu_ptr(hyperv_pcpu_input_arg);
 
         flush = *flush_pcpu;
 
@@ -203,7 +159,7 @@ static void hyperv_flush_tlb_others_ex(const struct cpumask *cpus,
 
         trace_hyperv_mmu_flush_tlb_others(cpus, info);
 
-        if (!pcpu_flush_ex || !hv_hypercall_pg)
+        if (!hv_hypercall_pg)
                 goto do_native;
 
         if (cpumask_empty(cpus))
@@ -211,10 +167,8 @@ static void hyperv_flush_tlb_others_ex(const struct cpumask *cpus,
 
         local_irq_save(flags);
 
-        flush_pcpu = this_cpu_ptr(pcpu_flush_ex);
-
-        if (unlikely(!*flush_pcpu))
-                *flush_pcpu = page_address(alloc_page(GFP_ATOMIC));
+        flush_pcpu = (struct hv_flush_pcpu_ex **)
+                     this_cpu_ptr(hyperv_pcpu_input_arg);
 
         flush = *flush_pcpu;
 
@@ -239,8 +193,8 @@ static void hyperv_flush_tlb_others_ex(const struct cpumask *cpus,
         flush->hv_vp_set.valid_bank_mask = 0;
 
         if (!cpumask_equal(cpus, cpu_present_mask)) {
-                flush->hv_vp_set.format = HV_GENERIC_SET_SPARCE_4K;
-                nr_bank = cpumask_to_vp_set(flush, cpus);
+                flush->hv_vp_set.format = HV_GENERIC_SET_SPARSE_4K;
+                nr_bank = cpumask_to_vpset(&(flush->hv_vp_set), cpus);
         }
 
         if (!nr_bank) {
@@ -296,14 +250,3 @@ void hyperv_setup_mmu_ops(void)
                 pv_mmu_ops.flush_tlb_others = hyperv_flush_tlb_others_ex;
         }
 }
-
-void hyper_alloc_mmu(void)
-{
-        if (!(ms_hyperv.hints & HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED))
-                return;
-
-        if (!(ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))
-                pcpu_flush = alloc_percpu(struct hv_flush_pcpu *);
-        else
-                pcpu_flush_ex = alloc_percpu(struct hv_flush_pcpu_ex *);
-}
diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index 416cb0e0c496..3bfa92c2793c 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -164,6 +164,11 @@
  */
 #define HV_X64_DEPRECATING_AEOI_RECOMMENDED     (1 << 9)
 
+/*
+ * Recommend using cluster IPI hypercalls.
+ */
+#define HV_X64_CLUSTER_IPI_RECOMMENDED         (1 << 10)
+
 /* Recommend using the newer ExProcessorMasks interface */
 #define HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED   (1 << 11)
 
@@ -329,12 +334,17 @@ struct hv_tsc_emulation_status {
 #define HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_MASK  \
                 (~((1ull << HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT) - 1))
 
+#define HV_IPI_LOW_VECTOR       0x10
+#define HV_IPI_HIGH_VECTOR      0xff
+
 /* Declare the various hypercall operations. */
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE      0x0002
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST       0x0003
 #define HVCALL_NOTIFY_LONG_SPIN_WAIT            0x0008
+#define HVCALL_SEND_IPI                         0x000b
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX  0x0013
 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX   0x0014
+#define HVCALL_SEND_IPI_EX                      0x0015
 #define HVCALL_POST_MESSAGE                     0x005c
 #define HVCALL_SIGNAL_EVENT                     0x005d
 
@@ -360,7 +370,7 @@ struct hv_tsc_emulation_status {
 #define HV_FLUSH_USE_EXTENDED_RANGE_FORMAT      BIT(3)
 
 enum HV_GENERIC_SET_FORMAT {
-        HV_GENERIC_SET_SPARCE_4K,
+        HV_GENERIC_SET_SPARSE_4K,
         HV_GENERIC_SET_ALL,
 };
 
@@ -706,4 +716,22 @@ struct hv_enlightened_vmcs {
 #define HV_STIMER_AUTOENABLE            (1ULL << 3)
 #define HV_STIMER_SINT(config)          (__u8)(((config) >> 16) & 0x0F)
 
+struct ipi_arg_non_ex {
+        u32 vector;
+        u32 reserved;
+        u64 cpu_mask;
+};
+
+struct hv_vpset {
+        u64 format;
+        u64 valid_bank_mask;
+        u64 bank_contents[];
+};
+
+struct ipi_arg_ex {
+        u32 vector;
+        u32 reserved;
+        struct hv_vpset vp_set;
+};
+
 #endif
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index b90e79610cf7..997192131b7b 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -122,6 +122,7 @@ static inline void hv_disable_stimer0_percpu_irq(int irq) {}
 #if IS_ENABLED(CONFIG_HYPERV)
 extern struct clocksource *hyperv_cs;
 extern void *hv_hypercall_pg;
+extern void  __percpu  **hyperv_pcpu_input_arg;
 
 static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
 {
@@ -258,9 +259,41 @@ static inline int hv_cpu_number_to_vp_number(int cpu_number)
         return hv_vp_index[cpu_number];
 }
 
-void hyperv_init(void);
+static inline int cpumask_to_vpset(struct hv_vpset *vpset,
+                                    const struct cpumask *cpus)
+{
+        int cpu, vcpu, vcpu_bank, vcpu_offset, nr_bank = 1;
+
+        /* valid_bank_mask can represent up to 64 banks */
+        if (hv_max_vp_index / 64 >= 64)
+                return 0;
+
+        /*
+         * Clear all banks up to the maximum possible bank as hv_flush_pcpu_ex
+         * structs are not cleared between calls, we risk flushing unneeded
+         * vCPUs otherwise.
+         */
+        for (vcpu_bank = 0; vcpu_bank <= hv_max_vp_index / 64; vcpu_bank++)
+                vpset->bank_contents[vcpu_bank] = 0;
+
+        /*
+         * Some banks may end up being empty but this is acceptable.
+         */
+        for_each_cpu(cpu, cpus) {
+                vcpu = hv_cpu_number_to_vp_number(cpu);
+                vcpu_bank = vcpu / 64;
+                vcpu_offset = vcpu % 64;
+                __set_bit(vcpu_offset, (unsigned long *)
+                          &vpset->bank_contents[vcpu_bank]);
+                if (vcpu_bank >= nr_bank)
+                        nr_bank = vcpu_bank + 1;
+        }
+        vpset->valid_bank_mask = GENMASK_ULL(nr_bank - 1, 0);
+        return nr_bank;
+}
+
+void __init hyperv_init(void);
 void hyperv_setup_mmu_ops(void);
-void hyper_alloc_mmu(void);
 void hyperv_report_panic(struct pt_regs *regs, long err);
 bool hv_is_hyperv_initialized(void);
 void hyperv_cleanup(void);
@@ -269,6 +302,13 @@ void hyperv_reenlightenment_intr(struct pt_regs *regs);
 void set_hv_tscchange_cb(void (*cb)(void));
 void clear_hv_tscchange_cb(void);
 void hyperv_stop_tsc_emulation(void);
+
+#ifdef CONFIG_X86_64
+void hv_apic_init(void);
+#else
+static inline void hv_apic_init(void) {}
+#endif
+
 #else /* CONFIG_HYPERV */
 static inline void hyperv_init(void) {}
 static inline bool hv_is_hyperv_initialized(void) { return false; }