7 files changed, 78 insertions, 9 deletions

diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h
index 1508e518c7e3..aac5fa62a86c 100644
--- a/arch/x86/include/asm/irq_vectors.h
+++ b/arch/x86/include/asm/irq_vectors.h
@@ -109,8 +109,8 @@
 
 #define UV_BAU_MESSAGE                  0xf5
 
-/* Xen vector callback to receive events in a HVM domain */
-#define XEN_HVM_EVTCHN_CALLBACK         0xf3
+/* Vector on which hypervisor callbacks will be delivered */
+#define HYPERVISOR_CALLBACK_VECTOR      0xf3
 
 /*
  * Local APIC timer IRQ vector is on a different priority level,
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 79ce5685ab64..c2934be2446a 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -11,4 +11,8 @@ struct ms_hyperv_info {
 
 extern struct ms_hyperv_info ms_hyperv;
 
+void hyperv_callback_vector(void);
+void hyperv_vector_handler(struct pt_regs *regs);
+void hv_register_vmbus_handler(int irq, irq_handler_t handler);
+
 #endif
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 0a630dd4b620..a7d26d83fb70 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -14,10 +14,15 @@
 #include <linux/time.h>
 #include <linux/clocksource.h>
 #include <linux/module.h>
+#include <linux/hardirq.h>
+#include <linux/interrupt.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>
 
 struct ms_hyperv_info ms_hyperv;
 EXPORT_SYMBOL_GPL(ms_hyperv);
@@ -30,6 +35,13 @@ static bool __init ms_hyperv_platform(void)
         if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
                 return false;
 
+        /*
+         * Xen emulates Hyper-V to support enlightened Windows.
+         * Check to see first if we are on a Xen Hypervisor.
+         */
+        if (xen_cpuid_base())
+                return false;
+
         cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
               &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
 
@@ -68,7 +80,14 @@ static void __init ms_hyperv_init_platform(void)
         printk(KERN_INFO "HyperV: features 0x%x, hints 0x%x\n",
                ms_hyperv.features, ms_hyperv.hints);
 
-        clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
+        if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
+                clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
+#if IS_ENABLED(CONFIG_HYPERV)
+        /*
+         * Setup the IDT for hypervisor callback.
+         */
+        alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, hyperv_callback_vector);
+#endif
 }
 
 const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
@@ -77,3 +96,36 @@ const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
         .init_platform          = ms_hyperv_init_platform,
 };
 EXPORT_SYMBOL(x86_hyper_ms_hyperv);
+
+#if IS_ENABLED(CONFIG_HYPERV)
+static int vmbus_irq = -1;
+static irq_handler_t vmbus_isr;
+
+void hv_register_vmbus_handler(int irq, irq_handler_t handler)
+{
+        vmbus_irq = irq;
+        vmbus_isr = handler;
+}
+
+void hyperv_vector_handler(struct pt_regs *regs)
+{
+        struct pt_regs *old_regs = set_irq_regs(regs);
+        struct irq_desc *desc;
+
+        irq_enter();
+        exit_idle();
+
+        desc = irq_to_desc(vmbus_irq);
+
+        if (desc)
+                generic_handle_irq_desc(vmbus_irq, desc);
+
+        irq_exit();
+        set_irq_regs(old_regs);
+}
+#else
+void hv_register_vmbus_handler(int irq, irq_handler_t handler)
+{
+}
+#endif
+EXPORT_SYMBOL_GPL(hv_register_vmbus_handler);
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 6ed91d9980e2..8831176aa5ef 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1091,11 +1091,18 @@ ENTRY(xen_failsafe_callback)
         _ASM_EXTABLE(4b,9b)
 ENDPROC(xen_failsafe_callback)
 
-BUILD_INTERRUPT3(xen_hvm_callback_vector, XEN_HVM_EVTCHN_CALLBACK,
+BUILD_INTERRUPT3(xen_hvm_callback_vector, HYPERVISOR_CALLBACK_VECTOR,
                 xen_evtchn_do_upcall)
 
 #endif  /* CONFIG_XEN */
 
+#if IS_ENABLED(CONFIG_HYPERV)
+
+BUILD_INTERRUPT3(hyperv_callback_vector, HYPERVISOR_CALLBACK_VECTOR,
+        hyperv_vector_handler)
+
+#endif /* CONFIG_HYPERV */
+
 #ifdef CONFIG_FUNCTION_TRACER
 #ifdef CONFIG_DYNAMIC_FTRACE
 
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index cb3c591339aa..048f2240f8e6 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1454,11 +1454,16 @@ ENTRY(xen_failsafe_callback)
         CFI_ENDPROC
 END(xen_failsafe_callback)
 
-apicinterrupt XEN_HVM_EVTCHN_CALLBACK \
+apicinterrupt HYPERVISOR_CALLBACK_VECTOR \
         xen_hvm_callback_vector xen_evtchn_do_upcall
 
 #endif /* CONFIG_XEN */
 
+#if IS_ENABLED(CONFIG_HYPERV)
+apicinterrupt HYPERVISOR_CALLBACK_VECTOR \
+        hyperv_callback_vector hyperv_vector_handler
+#endif /* CONFIG_HYPERV */
+
 /*
  * Some functions should be protected against kprobes
  */
diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
index b38ef6d8d049..64630f15f181 100644
--- a/drivers/hv/Kconfig
+++ b/drivers/hv/Kconfig
@@ -2,7 +2,7 @@ menu "Microsoft Hyper-V guest support"
 
 config HYPERV
         tristate "Microsoft Hyper-V client drivers"
-        depends on X86 && ACPI && PCI
+        depends on X86 && ACPI && PCI && X86_LOCAL_APIC
         help
           Select this option to run Linux as a Hyper-V client operating
           system.
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 74d77dfa5f63..22f77c5f6012 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -1787,7 +1787,7 @@ void xen_callback_vector(void)
         int rc;
         uint64_t callback_via;
         if (xen_have_vector_callback) {
-                callback_via = HVM_CALLBACK_VECTOR(XEN_HVM_EVTCHN_CALLBACK);
+                callback_via = HVM_CALLBACK_VECTOR(HYPERVISOR_CALLBACK_VECTOR);
                 rc = xen_set_callback_via(callback_via);
                 if (rc) {
                         printk(KERN_ERR "Request for Xen HVM callback vector"
@@ -1798,8 +1798,9 @@ void xen_callback_vector(void)
                 printk(KERN_INFO "Xen HVM callback vector for event delivery is "
                                 "enabled\n");
                 /* in the restore case the vector has already been allocated */
-                if (!test_bit(XEN_HVM_EVTCHN_CALLBACK, used_vectors))
-                        alloc_intr_gate(XEN_HVM_EVTCHN_CALLBACK, xen_hvm_callback_vector);
+                if (!test_bit(HYPERVISOR_CALLBACK_VECTOR, used_vectors))
+                        alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR,
+                                        xen_hvm_callback_vector);
         }
 }
 #else