1 files changed, 53 insertions, 1 deletions

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);