hyperv: Add reference counter support

Adds support for the Hyper-V partition reference counter.

Change-Id: Ie74b4d3af1b320b7b724776bdb6a22f643873f80
Reviewed-on: https://review.haiku-os.org/c/haiku/+/10500
Tested-by: Commit checker robot <[email protected]>
Reviewed-by: Jérôme Duval <[email protected]>

headers/private/hyperv/hyperv.h

@@ -51,6 +51,7 @@ typedef struct hyperv_device_interface {
 	driver_module_info info;
 
 	uint32 (*get_bus_version)(hyperv_device cookie);
+	status_t (*get_reference_counter)(hyperv_device cookie, uint64* _count);
 	status_t (*open)(hyperv_device cookie, uint32 txLength, uint32 rxLength,
 		hyperv_device_callback callback, void* callbackData);
 	void (*close)(hyperv_device cookie);

src/add-ons/kernel/bus_managers/hyperv/VMBusDevice.cpp

@@ -12,6 +12,7 @@ VMBusDevice::VMBusDevice(device_node* node)
 	fNode(node),
 	fStatus(B_NO_INIT),
 	fChannelID(0),
+	fReferenceCounterSupported(false),
 	fDPCHandle(NULL),
 	fIsOpen(false),
 	fRingGPADL(0),
@@ -41,6 +42,9 @@ VMBusDevice::VMBusDevice(device_node* node)
 	mutex_init(&fLock, "vmbus device lock");
 	B_INITIALIZE_SPINLOCK(&fTXLock);
 	B_INITIALIZE_SPINLOCK(&fRXLock);
+
+	fReferenceCounterSupported = _IsReferenceCounterSupported();
+	TRACE("Reference counter: %s\n", fReferenceCounterSupported ? "yes" : "no");
 }
 
 

src/add-ons/kernel/bus_managers/hyperv/VMBusDeviceModule.cpp

@@ -56,6 +56,15 @@ vmbus_device_get_bus_version(hyperv_device cookie)
 }
 
 
+static status_t
+vmbus_device_get_reference_counter(hyperv_device cookie, uint64* _count)
+{
+	CALLED();
+	VMBusDevice* device = reinterpret_cast<VMBusDevice*>(cookie);
+	return device->GetReferenceCounter(_count);
+}
+
+
 static status_t
 vmbus_device_open(hyperv_device cookie, uint32 txLength, uint32 rxLength,
 	hyperv_device_callback callback, void* callbackData)
@@ -153,6 +162,7 @@ hyperv_device_interface gVMBusDeviceModule = {
 	},
 
 	vmbus_device_get_bus_version,
+	vmbus_device_get_reference_counter,
 	vmbus_device_open,
 	vmbus_device_close,
 	vmbus_device_read_packet,

src/add-ons/kernel/bus_managers/hyperv/VMBusDevicePrivate.h

@@ -47,6 +47,7 @@ public:
 			status_t				InitCheck() const { return fStatus; }
 
 			uint32					GetBusVersion();
+			status_t				GetReferenceCounter(uint64* _count);
 			status_t				Open(uint32 txLength, uint32 rxLength,
 										hyperv_device_callback callback, void* callbackData);
 			void					Close();
@@ -64,6 +65,7 @@ public:
 			status_t				FreeGPADL(uint32 gpadl);
 
 private:
+			bool					_IsReferenceCounterSupported();
 	static	void					_CallbackHandler(void* arg);
 	static	void					_DPCHandler(void* arg);
 
@@ -78,6 +80,7 @@ private:
 			device_node*			fNode;
 			status_t				fStatus;
 			uint32					fChannelID;
+			bool					fReferenceCounterSupported;
 			mutex					fLock;
 			void*					fDPCHandle;
 			bool					fIsOpen;

src/add-ons/kernel/bus_managers/hyperv/arch/x86/Jamfile

@@ -11,4 +11,5 @@ SubDirHdrs $(HAIKU_TOP) src add-ons kernel bus_managers acpi acpica include plat
 
 KernelStaticLibrary hyperv_arch_bus_manager :
 	VMBus_x86.cpp
+	VMBusDevice_x86.cpp
 	;

src/add-ons/kernel/bus_managers/hyperv/arch/x86/VMBusDevice_x86.cpp

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2026 John Davis
+ * All rights reserved. Distributed under the terms of the MIT License.
+ */
+
+
+#include <arch_cpu.h>
+
+#include "hyperv_cpu.h"
+#include "VMBusDevicePrivate.h"
+
+
+status_t
+VMBusDevice::GetReferenceCounter(uint64* _counter)
+{
+	if (!fReferenceCounterSupported)
+		return B_NOT_SUPPORTED;
+
+	*_counter = x86_read_msr(IA32_MSR_HV_TIME_REF_COUNT);
+	return B_OK;
+}
+
+
+bool
+VMBusDevice::_IsReferenceCounterSupported()
+{
+	cpuid_info cpuInfo;
+	get_cpuid(&cpuInfo, IA32_CPUID_LEAF_HV_FEAT_ID, 0);
+	return (cpuInfo.regs.eax & HV_CPUID_FEATURE_TIME_REF_COUNTER) != 0;
+}