Staging: hv: add the Hyper-V virtual storage driver

This is the virtual storage driver when running Linux on top of Hyper-V.

Signed-off-by: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 967 insertions, 0 deletions

diff --git a/drivers/staging/hv/StorVsc.c b/drivers/staging/hv/StorVsc.c
new file mode 100644
index 000000000000..8a1d77667542
--- /dev/null
+++ b/drivers/staging/hv/StorVsc.c
@@ -0,0 +1,967 @@
+/*
+ *
+ * Copyright (c) 2009, Microsoft Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place - Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ *
+ */
+
+
+#include "logging.h"
+
+#include "StorVscApi.h"
+#include "VmbusPacketFormat.h"
+#include "vstorage.h"
+
+
+//
+// #defines
+//
+
+//
+// Data types
+//
+
+typedef struct _STORVSC_REQUEST_EXTENSION {
+	//LIST_ENTRY						ListEntry;
+
+	STORVSC_REQUEST					*Request;
+	DEVICE_OBJECT					*Device;
+
+	// Synchronize the request/response if needed
+	HANDLE							WaitEvent;
+
+	VSTOR_PACKET					VStorPacket;
+} STORVSC_REQUEST_EXTENSION;
+
+
+// A storvsc device is a device object that contains a vmbus channel
+typedef struct _STORVSC_DEVICE{
+	DEVICE_OBJECT				*Device;
+
+	int							RefCount; // 0 indicates the device is being destroyed
+
+	int							NumOutstandingRequests;
+
+	//  Each unique Port/Path/Target represents 1 channel ie scsi controller. In reality, the pathid, targetid is always 0
+	// and the port is set by us
+	ULONG						PortNumber;
+    UCHAR						PathId;
+    UCHAR						TargetId;
+
+	//LIST_ENTRY					OutstandingRequestList;
+	//HANDLE						OutstandingRequestLock;
+
+	// Used for vsc/vsp channel reset process
+	STORVSC_REQUEST_EXTENSION	InitRequest;
+
+	STORVSC_REQUEST_EXTENSION	ResetRequest;
+
+} STORVSC_DEVICE;
+
+
+//
+// Globals
+//
+static const char* gDriverName="storvsc";
+
+//{ba6163d9-04a1-4d29-b605-72e2ffb1dc7f}
+static const GUID gStorVscDeviceType={
+	.Data = {0xd9, 0x63, 0x61, 0xba, 0xa1, 0x04, 0x29, 0x4d, 0xb6, 0x05, 0x72, 0xe2, 0xff, 0xb1, 0xdc, 0x7f}
+};
+
+//
+// Internal routines
+//
+static int
+StorVscOnDeviceAdd(
+	DEVICE_OBJECT	*Device,
+	void			*AdditionalInfo
+	);
+
+static int
+StorVscOnDeviceRemove(
+	DEVICE_OBJECT	*Device
+	);
+
+static int
+StorVscOnIORequest(
+	DEVICE_OBJECT	*Device,
+	STORVSC_REQUEST	*Request
+	);
+
+static int
+StorVscOnHostReset(
+	DEVICE_OBJECT	*Device
+	);
+
+static void
+StorVscOnCleanup(
+	DRIVER_OBJECT	*Device
+	);
+
+static void
+StorVscOnChannelCallback(
+	PVOID Context
+	);
+
+static void
+StorVscOnIOCompletion(
+	DEVICE_OBJECT	*Device,
+	VSTOR_PACKET	*VStorPacket,
+	STORVSC_REQUEST_EXTENSION *RequestExt
+	);
+
+static void
+StorVscOnReceive(
+	DEVICE_OBJECT	*Device,
+	VSTOR_PACKET	*VStorPacket,
+	STORVSC_REQUEST_EXTENSION *RequestExt
+	);
+
+static int
+StorVscConnectToVsp(
+	DEVICE_OBJECT	*Device
+	);
+
+static inline STORVSC_DEVICE* AllocStorDevice(DEVICE_OBJECT *Device)
+{
+	STORVSC_DEVICE *storDevice;
+
+	storDevice = MemAllocZeroed(sizeof(STORVSC_DEVICE));
+	if (!storDevice)
+		return NULL;
+
+	// Set to 2 to allow both inbound and outbound traffics
+	// (ie GetStorDevice() and MustGetStorDevice()) to proceed.
+	InterlockedCompareExchange(&storDevice->RefCount, 2, 0);
+
+	storDevice->Device = Device;
+	Device->Extension = storDevice;
+
+	return storDevice;
+}
+
+static inline void FreeStorDevice(STORVSC_DEVICE *Device)
+{
+	ASSERT(Device->RefCount == 0);
+	MemFree(Device);
+}
+
+// Get the stordevice object iff exists and its refcount > 1
+static inline STORVSC_DEVICE* GetStorDevice(DEVICE_OBJECT *Device)
+{
+	STORVSC_DEVICE *storDevice;
+
+	storDevice = (STORVSC_DEVICE*)Device->Extension;
+	if (storDevice && storDevice->RefCount > 1)
+	{
+		InterlockedIncrement(&storDevice->RefCount);
+	}
+	else
+	{
+		storDevice = NULL;
+	}
+
+	return storDevice;
+}
+
+// Get the stordevice object iff exists and its refcount > 0
+static inline STORVSC_DEVICE* MustGetStorDevice(DEVICE_OBJECT *Device)
+{
+	STORVSC_DEVICE *storDevice;
+
+	storDevice = (STORVSC_DEVICE*)Device->Extension;
+	if (storDevice && storDevice->RefCount)
+	{
+		InterlockedIncrement(&storDevice->RefCount);
+	}
+	else
+	{
+		storDevice = NULL;
+	}
+
+	return storDevice;
+}
+
+static inline void PutStorDevice(DEVICE_OBJECT *Device)
+{
+	STORVSC_DEVICE *storDevice;
+
+	storDevice = (STORVSC_DEVICE*)Device->Extension;
+	ASSERT(storDevice);
+
+	InterlockedDecrement(&storDevice->RefCount);
+	ASSERT(storDevice->RefCount);
+}
+
+// Drop ref count to 1 to effectively disable GetStorDevice()
+static inline STORVSC_DEVICE* ReleaseStorDevice(DEVICE_OBJECT *Device)
+{
+	STORVSC_DEVICE *storDevice;
+
+	storDevice = (STORVSC_DEVICE*)Device->Extension;
+	ASSERT(storDevice);
+
+	// Busy wait until the ref drop to 2, then set it to 1
+	while (InterlockedCompareExchange(&storDevice->RefCount, 1, 2) != 2)
+	{
+		Sleep(100);
+	}
+
+	return storDevice;
+}
+
+// Drop ref count to 0. No one can use StorDevice object.
+static inline STORVSC_DEVICE* FinalReleaseStorDevice(DEVICE_OBJECT *Device)
+{
+	STORVSC_DEVICE *storDevice;
+
+	storDevice = (STORVSC_DEVICE*)Device->Extension;
+	ASSERT(storDevice);
+
+	// Busy wait until the ref drop to 1, then set it to 0
+	while (InterlockedCompareExchange(&storDevice->RefCount, 0, 1) != 1)
+	{
+		Sleep(100);
+	}
+
+	Device->Extension = NULL;
+	return storDevice;
+}
+
+/*++;
+
+
+Name:
+	StorVscInitialize()
+
+Description:
+	Main entry point
+
+--*/
+int
+StorVscInitialize(
+	DRIVER_OBJECT *Driver
+	)
+{
+	STORVSC_DRIVER_OBJECT* storDriver = (STORVSC_DRIVER_OBJECT*)Driver;
+	int ret=0;
+
+	DPRINT_ENTER(STORVSC);
+
+	DPRINT_DBG(STORVSC, "sizeof(STORVSC_REQUEST)=%d sizeof(STORVSC_REQUEST_EXTENSION)=%d sizeof(VSTOR_PACKET)=%d, sizeof(VMSCSI_REQUEST)=%d",
+		sizeof(STORVSC_REQUEST), sizeof(STORVSC_REQUEST_EXTENSION), sizeof(VSTOR_PACKET), sizeof(VMSCSI_REQUEST));
+
+	// Make sure we are at least 2 pages since 1 page is used for control
+	ASSERT(storDriver->RingBufferSize >= (PAGE_SIZE << 1));
+
+	Driver->name = gDriverName;
+	memcpy(&Driver->deviceType, &gStorVscDeviceType, sizeof(GUID));
+
+	storDriver->RequestExtSize			= sizeof(STORVSC_REQUEST_EXTENSION);
+
+	// Divide the ring buffer data size (which is 1 page less than the ring buffer size since that page is reserved for the ring buffer indices)
+	// by the max request size (which is VMBUS_CHANNEL_PACKET_MULITPAGE_BUFFER + VSTOR_PACKET + UINT64)
+	storDriver->MaxOutstandingRequestsPerChannel =
+		((storDriver->RingBufferSize - PAGE_SIZE) / ALIGN_UP(MAX_MULTIPAGE_BUFFER_PACKET + sizeof(VSTOR_PACKET) + sizeof(UINT64),sizeof(UINT64)));
+
+	DPRINT_INFO(STORVSC, "max io %u, currently %u\n", storDriver->MaxOutstandingRequestsPerChannel, STORVSC_MAX_IO_REQUESTS);
+
+	// Setup the dispatch table
+	storDriver->Base.OnDeviceAdd			= StorVscOnDeviceAdd;
+	storDriver->Base.OnDeviceRemove		= StorVscOnDeviceRemove;
+	storDriver->Base.OnCleanup			= StorVscOnCleanup;
+
+	storDriver->OnIORequest				= StorVscOnIORequest;
+	storDriver->OnHostReset				= StorVscOnHostReset;
+
+	DPRINT_EXIT(STORVSC);
+
+	return ret;
+}
+
+/*++
+
+Name:
+	StorVscOnDeviceAdd()
+
+Description:
+	Callback when the device belonging to this driver is added
+
+--*/
+int
+StorVscOnDeviceAdd(
+	DEVICE_OBJECT	*Device,
+	void			*AdditionalInfo
+	)
+{
+	int ret=0;
+	STORVSC_DEVICE *storDevice;
+	//VMSTORAGE_CHANNEL_PROPERTIES *props;
+	STORVSC_DEVICE_INFO *deviceInfo = (STORVSC_DEVICE_INFO*)AdditionalInfo;
+
+	DPRINT_ENTER(STORVSC);
+
+	storDevice = AllocStorDevice(Device);
+	if (!storDevice)
+	{
+		ret = -1;
+		goto Cleanup;
+	}
+
+	// Save the channel properties to our storvsc channel
+	//props = (VMSTORAGE_CHANNEL_PROPERTIES*) channel->offerMsg.Offer.u.Standard.UserDefined;
+
+	// FIXME:
+	// If we support more than 1 scsi channel, we need to set the port number here
+	// to the scsi channel but how do we get the scsi channel prior to the bus scan
+	/*storChannel->PortNumber = 0;
+	storChannel->PathId = props->PathId;
+	storChannel->TargetId = props->TargetId;*/
+
+	storDevice->PortNumber = deviceInfo->PortNumber;
+	// Send it back up
+	ret = StorVscConnectToVsp(Device);
+
+	//deviceInfo->PortNumber = storDevice->PortNumber;
+	deviceInfo->PathId = storDevice->PathId;
+	deviceInfo->TargetId = storDevice->TargetId;
+
+	DPRINT_DBG(STORVSC, "assigned port %u, path %u target %u\n", storDevice->PortNumber, storDevice->PathId, storDevice->TargetId);
+
+Cleanup:
+	DPRINT_EXIT(STORVSC);
+
+	return ret;
+}
+
+static int StorVscChannelInit(DEVICE_OBJECT *Device)
+{
+	int ret=0;
+	STORVSC_DEVICE *storDevice;
+	STORVSC_REQUEST_EXTENSION *request;
+	VSTOR_PACKET *vstorPacket;
+
+	storDevice = GetStorDevice(Device);
+	if (!storDevice)
+	{
+		DPRINT_ERR(STORVSC, "unable to get stor device...device being destroyed?");
+		DPRINT_EXIT(STORVSC);
+		return -1;
+	}
+
+	request = &storDevice->InitRequest;
+	vstorPacket = &request->VStorPacket;
+
+	// Now, initiate the vsc/vsp initialization protocol on the open channel
+
+	memset(request, sizeof(STORVSC_REQUEST_EXTENSION), 0);
+	request->WaitEvent = WaitEventCreate();
+
+	vstorPacket->Operation = VStorOperationBeginInitialization;
+	vstorPacket->Flags = REQUEST_COMPLETION_FLAG;
+
+	/*SpinlockAcquire(gDriverExt.packetListLock);
+	INSERT_TAIL_LIST(&gDriverExt.packetList, &packet->listEntry.entry);
+	SpinlockRelease(gDriverExt.packetListLock);*/
+
+	DPRINT_INFO(STORVSC, "BEGIN_INITIALIZATION_OPERATION...");
+
+	ret = Device->Driver->VmbusChannelInterface.SendPacket(Device,
+															vstorPacket,
+															sizeof(VSTOR_PACKET),
+															(ULONG_PTR)request,
+															VmbusPacketTypeDataInBand,
+															VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	if ( ret != 0)
+	{
+		DPRINT_ERR(STORVSC, "unable to send BEGIN_INITIALIZATION_OPERATION");
+		goto Cleanup;
+	}
+
+	WaitEventWait(request->WaitEvent);
+
+	if (vstorPacket->Operation != VStorOperationCompleteIo || vstorPacket->Status != 0)
+	{
+		DPRINT_ERR(STORVSC, "BEGIN_INITIALIZATION_OPERATION failed (op %d status 0x%x)", vstorPacket->Operation, vstorPacket->Status);
+		goto Cleanup;
+	}
+
+	DPRINT_INFO(STORVSC, "QUERY_PROTOCOL_VERSION_OPERATION...");
+
+	// reuse the packet for version range supported
+	memset(vstorPacket, sizeof(VSTOR_PACKET), 0);
+	vstorPacket->Operation = VStorOperationQueryProtocolVersion;
+	vstorPacket->Flags = REQUEST_COMPLETION_FLAG;
+
+    vstorPacket->Version.MajorMinor = VMSTOR_PROTOCOL_VERSION_CURRENT;
+    FILL_VMSTOR_REVISION(vstorPacket->Version.Revision);
+
+	ret = Device->Driver->VmbusChannelInterface.SendPacket(Device,
+															vstorPacket,
+															sizeof(VSTOR_PACKET),
+															(ULONG_PTR)request,
+															VmbusPacketTypeDataInBand,
+															VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	if ( ret != 0)
+	{
+		DPRINT_ERR(STORVSC, "unable to send BEGIN_INITIALIZATION_OPERATION");
+		goto Cleanup;
+	}
+
+	WaitEventWait(request->WaitEvent);
+
+	// TODO: Check returned version
+	if (vstorPacket->Operation != VStorOperationCompleteIo || vstorPacket->Status != 0)
+	{
+		DPRINT_ERR(STORVSC, "QUERY_PROTOCOL_VERSION_OPERATION failed (op %d status 0x%x)", vstorPacket->Operation, vstorPacket->Status);
+		goto Cleanup;
+	}
+
+	// Query channel properties
+	DPRINT_INFO(STORVSC, "QUERY_PROPERTIES_OPERATION...");
+
+	memset(vstorPacket, sizeof(VSTOR_PACKET), 0);
+    vstorPacket->Operation = VStorOperationQueryProperties;
+	vstorPacket->Flags = REQUEST_COMPLETION_FLAG;
+    vstorPacket->StorageChannelProperties.PortNumber = storDevice->PortNumber;
+
+	ret = Device->Driver->VmbusChannelInterface.SendPacket(Device,
+															vstorPacket,
+															sizeof(VSTOR_PACKET),
+															(ULONG_PTR)request,
+															VmbusPacketTypeDataInBand,
+															VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+
+	if ( ret != 0)
+	{
+		DPRINT_ERR(STORVSC, "unable to send QUERY_PROPERTIES_OPERATION");
+		goto Cleanup;
+	}
+
+	WaitEventWait(request->WaitEvent);
+
+	// TODO: Check returned version
+	if (vstorPacket->Operation != VStorOperationCompleteIo || vstorPacket->Status != 0)
+	{
+		DPRINT_ERR(STORVSC, "QUERY_PROPERTIES_OPERATION failed (op %d status 0x%x)", vstorPacket->Operation, vstorPacket->Status);
+		goto Cleanup;
+	}
+
+	//storDevice->PortNumber = vstorPacket->StorageChannelProperties.PortNumber;
+	storDevice->PathId = vstorPacket->StorageChannelProperties.PathId;
+	storDevice->TargetId = vstorPacket->StorageChannelProperties.TargetId;
+
+	DPRINT_DBG(STORVSC, "channel flag 0x%x, max xfer len 0x%x", vstorPacket->StorageChannelProperties.Flags, vstorPacket->StorageChannelProperties.MaxTransferBytes);
+
+	DPRINT_INFO(STORVSC, "END_INITIALIZATION_OPERATION...");
+
+	memset(vstorPacket, sizeof(VSTOR_PACKET), 0);
+    vstorPacket->Operation = VStorOperationEndInitialization;
+	vstorPacket->Flags = REQUEST_COMPLETION_FLAG;
+
+	ret = Device->Driver->VmbusChannelInterface.SendPacket(Device,
+															vstorPacket,
+															sizeof(VSTOR_PACKET),
+															(ULONG_PTR)request,
+															VmbusPacketTypeDataInBand,
+															VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+
+	if ( ret != 0)
+	{
+		DPRINT_ERR(STORVSC, "unable to send END_INITIALIZATION_OPERATION");
+		goto Cleanup;
+	}
+
+	WaitEventWait(request->WaitEvent);
+
+	if (vstorPacket->Operation != VStorOperationCompleteIo || vstorPacket->Status != 0)
+	{
+		DPRINT_ERR(STORVSC, "END_INITIALIZATION_OPERATION failed (op %d status 0x%x)", vstorPacket->Operation, vstorPacket->Status);
+		goto Cleanup;
+	}
+
+	DPRINT_INFO(STORVSC, "**** storage channel up and running!! ****");
+
+Cleanup:
+	if (request->WaitEvent)
+	{
+		WaitEventClose(request->WaitEvent);
+		request->WaitEvent = NULL;
+	}
+
+	PutStorDevice(Device);
+
+	DPRINT_EXIT(STORVSC);
+	return ret;
+}
+
+
+int
+StorVscConnectToVsp(
+	DEVICE_OBJECT	*Device
+	)
+{
+	int ret=0;
+    VMSTORAGE_CHANNEL_PROPERTIES props;
+
+	STORVSC_DRIVER_OBJECT *storDriver = (STORVSC_DRIVER_OBJECT*) Device->Driver;;
+
+	memset(&props, sizeof(VMSTORAGE_CHANNEL_PROPERTIES), 0);
+
+	// Open the channel
+	ret = Device->Driver->VmbusChannelInterface.Open(Device,
+		storDriver->RingBufferSize,
+		storDriver->RingBufferSize,
+		(PVOID)&props,
+		sizeof(VMSTORAGE_CHANNEL_PROPERTIES),
+		StorVscOnChannelCallback,
+		Device
+		);
+
+	DPRINT_DBG(STORVSC, "storage props: path id %d, tgt id %d, max xfer %d", props.PathId, props.TargetId, props.MaxTransferBytes);
+
+	if (ret != 0)
+	{
+		DPRINT_ERR(STORVSC, "unable to open channel: %d", ret);
+		return -1;
+	}
+
+	ret = StorVscChannelInit(Device);
+
+	return ret;
+}
+
+
+/*++
+
+Name:
+	StorVscOnDeviceRemove()
+
+Description:
+	Callback when the our device is being removed
+
+--*/
+int
+StorVscOnDeviceRemove(
+	DEVICE_OBJECT *Device
+	)
+{
+	STORVSC_DEVICE *storDevice;
+	int ret=0;
+
+	DPRINT_ENTER(STORVSC);
+
+	DPRINT_INFO(STORVSC, "disabling storage device (%p)...", Device->Extension);
+
+	storDevice = ReleaseStorDevice(Device);
+
+	// At this point, all outbound traffic should be disable. We only allow inbound traffic (responses) to proceed
+	// so that outstanding requests can be completed.
+	while (storDevice->NumOutstandingRequests)
+	{
+		DPRINT_INFO(STORVSC, "waiting for %d requests to complete...", storDevice->NumOutstandingRequests);
+
+		Sleep(100);
+	}
+
+	DPRINT_INFO(STORVSC, "removing storage device (%p)...", Device->Extension);
+
+	storDevice = FinalReleaseStorDevice(Device);
+
+	DPRINT_INFO(STORVSC, "storage device (%p) safe to remove", storDevice);
+
+	// Close the channel
+	Device->Driver->VmbusChannelInterface.Close(Device);
+
+	FreeStorDevice(storDevice);
+
+	DPRINT_EXIT(STORVSC);
+	return ret;
+}
+
+
+//static void
+//StorVscOnTargetRescan(
+//	void *Context
+//	)
+//{
+//	DEVICE_OBJECT *device=(DEVICE_OBJECT*)Context;
+//	STORVSC_DRIVER_OBJECT *storDriver;
+//
+//	DPRINT_ENTER(STORVSC);
+//
+//	storDriver = (STORVSC_DRIVER_OBJECT*) device->Driver;
+//	storDriver->OnHostRescan(device);
+//
+//	DPRINT_EXIT(STORVSC);
+//}
+
+int
+StorVscOnHostReset(
+	DEVICE_OBJECT *Device
+	)
+{
+	int ret=0;
+
+	STORVSC_DEVICE *storDevice;
+	STORVSC_REQUEST_EXTENSION *request;
+	VSTOR_PACKET *vstorPacket;
+
+	DPRINT_ENTER(STORVSC);
+
+	DPRINT_INFO(STORVSC, "resetting host adapter...");
+
+	storDevice = GetStorDevice(Device);
+	if (!storDevice)
+	{
+		DPRINT_ERR(STORVSC, "unable to get stor device...device being destroyed?");
+		DPRINT_EXIT(STORVSC);
+		return -1;
+	}
+
+	request = &storDevice->ResetRequest;
+	vstorPacket = &request->VStorPacket;
+
+	request->WaitEvent = WaitEventCreate();
+
+    vstorPacket->Operation = VStorOperationResetBus;
+    vstorPacket->Flags = REQUEST_COMPLETION_FLAG;
+    vstorPacket->VmSrb.PathId = storDevice->PathId;
+
+	ret = Device->Driver->VmbusChannelInterface.SendPacket(Device,
+															vstorPacket,
+															sizeof(VSTOR_PACKET),
+															(ULONG_PTR)&storDevice->ResetRequest,
+															VmbusPacketTypeDataInBand,
+															VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	if (ret != 0)
+	{
+		DPRINT_ERR(STORVSC, "Unable to send reset packet %p ret %d", vstorPacket, ret);
+		goto Cleanup;
+	}
+
+	// FIXME: Add a timeout
+	WaitEventWait(request->WaitEvent);
+
+	WaitEventClose(request->WaitEvent);
+	DPRINT_INFO(STORVSC, "host adapter reset completed");
+
+	// At this point, all outstanding requests in the adapter should have been flushed out and return to us
+
+Cleanup:
+	PutStorDevice(Device);
+	DPRINT_EXIT(STORVSC);
+	return ret;
+}
+
+/*++
+
+Name:
+	StorVscOnIORequest()
+
+Description:
+	Callback to initiate an I/O request
+
+--*/
+int
+StorVscOnIORequest(
+	DEVICE_OBJECT	*Device,
+	STORVSC_REQUEST	*Request
+	)
+{
+	STORVSC_DEVICE *storDevice;
+	STORVSC_REQUEST_EXTENSION* requestExtension = (STORVSC_REQUEST_EXTENSION*) Request->Extension;
+	VSTOR_PACKET* vstorPacket =&requestExtension->VStorPacket;
+	int ret=0;
+
+	DPRINT_ENTER(STORVSC);
+
+	storDevice = GetStorDevice(Device);
+
+	DPRINT_DBG(STORVSC, "enter - Device %p, DeviceExt %p, Request %p, Extension %p",
+		Device, storDevice, Request, requestExtension);
+
+	DPRINT_DBG(STORVSC, "req %p len %d bus %d, target %d, lun %d cdblen %d",
+		Request, Request->DataBuffer.Length, Request->Bus, Request->TargetId, Request->LunId, Request->CdbLen);
+
+	if (!storDevice)
+	{
+		DPRINT_ERR(STORVSC, "unable to get stor device...device being destroyed?");
+		DPRINT_EXIT(STORVSC);
+		return -2;
+	}
+
+	//PrintBytes(Request->Cdb, Request->CdbLen);
+
+	requestExtension->Request = Request;
+	requestExtension->Device  = Device;
+
+	memset(vstorPacket, 0 , sizeof(VSTOR_PACKET));
+
+	vstorPacket->Flags |= REQUEST_COMPLETION_FLAG;
+
+    vstorPacket->VmSrb.Length = sizeof(VMSCSI_REQUEST);
+
+	vstorPacket->VmSrb.PortNumber = Request->Host;
+    vstorPacket->VmSrb.PathId = Request->Bus;
+    vstorPacket->VmSrb.TargetId = Request->TargetId;
+    vstorPacket->VmSrb.Lun = Request->LunId;
+
+	vstorPacket->VmSrb.SenseInfoLength = SENSE_BUFFER_SIZE;
+
+	// Copy over the scsi command descriptor block
+    vstorPacket->VmSrb.CdbLength = Request->CdbLen;
+	memcpy(&vstorPacket->VmSrb.Cdb, Request->Cdb, Request->CdbLen);
+
+	vstorPacket->VmSrb.DataIn = Request->Type;
+	vstorPacket->VmSrb.DataTransferLength = Request->DataBuffer.Length;
+
+	vstorPacket->Operation = VStorOperationExecuteSRB;
+
+	DPRINT_DBG(STORVSC, "srb - len %d port %d, path %d, target %d, lun %d senselen %d cdblen %d",
+		vstorPacket->VmSrb.Length,
+		vstorPacket->VmSrb.PortNumber,
+		vstorPacket->VmSrb.PathId,
+		vstorPacket->VmSrb.TargetId,
+		vstorPacket->VmSrb.Lun,
+		vstorPacket->VmSrb.SenseInfoLength,
+		vstorPacket->VmSrb.CdbLength);
+
+	if (requestExtension->Request->DataBuffer.Length)
+	{
+		ret = Device->Driver->VmbusChannelInterface.SendPacketMultiPageBuffer(Device,
+				&requestExtension->Request->DataBuffer,
+				vstorPacket,
+				sizeof(VSTOR_PACKET),
+				(ULONG_PTR)requestExtension);
+	}
+	else
+	{
+		ret = Device->Driver->VmbusChannelInterface.SendPacket(Device,
+															vstorPacket,
+															sizeof(VSTOR_PACKET),
+															(ULONG_PTR)requestExtension,
+															VmbusPacketTypeDataInBand,
+															VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	}
+
+	if (ret != 0)
+	{
+		DPRINT_DBG(STORVSC, "Unable to send packet %p ret %d", vstorPacket, ret);
+	}
+
+	InterlockedIncrement(&storDevice->NumOutstandingRequests);
+
+	PutStorDevice(Device);
+
+	DPRINT_EXIT(STORVSC);
+	return ret;
+}
+
+/*++
+
+Name:
+	StorVscOnCleanup()
+
+Description:
+	Perform any cleanup when the driver is removed
+
+--*/
+void
+StorVscOnCleanup(
+	DRIVER_OBJECT *Driver
+	)
+{
+	DPRINT_ENTER(STORVSC);
+	DPRINT_EXIT(STORVSC);
+}
+
+
+static void
+StorVscOnIOCompletion(
+	DEVICE_OBJECT	*Device,
+	VSTOR_PACKET	*VStorPacket,
+	STORVSC_REQUEST_EXTENSION *RequestExt
+	)
+{
+	STORVSC_REQUEST *request;
+	STORVSC_DEVICE *storDevice;
+
+	DPRINT_ENTER(STORVSC);
+
+	storDevice = MustGetStorDevice(Device);
+	if (!storDevice)
+	{
+		DPRINT_ERR(STORVSC, "unable to get stor device...device being destroyed?");
+		DPRINT_EXIT(STORVSC);
+		return;
+	}
+
+	DPRINT_DBG(STORVSC, "IO_COMPLETE_OPERATION - request extension %p completed bytes xfer %u",
+		RequestExt, VStorPacket->VmSrb.DataTransferLength);
+
+	ASSERT(RequestExt != NULL);
+	ASSERT(RequestExt->Request != NULL);
+
+	request = RequestExt->Request;
+
+	ASSERT(request->OnIOCompletion != NULL);
+
+	// Copy over the status...etc
+	request->Status = VStorPacket->VmSrb.ScsiStatus;
+
+	if (request->Status != 0 || VStorPacket->VmSrb.SrbStatus != 1)
+	{
+		DPRINT_WARN(STORVSC, "cmd 0x%x scsi status 0x%x srb status 0x%x\n",
+			request->Cdb[0],
+			VStorPacket->VmSrb.ScsiStatus,
+			VStorPacket->VmSrb.SrbStatus);
+	}
+
+	if ((request->Status & 0xFF) == 0x02) // CHECK_CONDITION
+	{
+		if (VStorPacket->VmSrb.SrbStatus & 0x80) // autosense data available
+		{
+			DPRINT_WARN(STORVSC, "storvsc pkt %p autosense data valid - len %d\n",
+				RequestExt, VStorPacket->VmSrb.SenseInfoLength);
+
+			ASSERT(VStorPacket->VmSrb.SenseInfoLength <=  request->SenseBufferSize);
+			memcpy(request->SenseBuffer,
+				VStorPacket->VmSrb.SenseData,
+				VStorPacket->VmSrb.SenseInfoLength);
+
+			request->SenseBufferSize = VStorPacket->VmSrb.SenseInfoLength;
+		}
+	}
+
+	// TODO:
+	request->BytesXfer = VStorPacket->VmSrb.DataTransferLength;
+
+	request->OnIOCompletion(request);
+
+	InterlockedDecrement(&storDevice->NumOutstandingRequests);
+
+	PutStorDevice(Device);
+
+	DPRINT_EXIT(STORVSC);
+}
+
+
+static void
+StorVscOnReceive(
+	DEVICE_OBJECT	*Device,
+	VSTOR_PACKET	*VStorPacket,
+	STORVSC_REQUEST_EXTENSION *RequestExt
+	)
+{
+	switch(VStorPacket->Operation)
+	{
+		case VStorOperationCompleteIo:
+
+			DPRINT_DBG(STORVSC, "IO_COMPLETE_OPERATION");
+			StorVscOnIOCompletion(Device, VStorPacket, RequestExt);
+			break;
+
+		//case ENUMERATE_DEVICE_OPERATION:
+
+		//	DPRINT_INFO(STORVSC, "ENUMERATE_DEVICE_OPERATION");
+
+		//	StorVscOnTargetRescan(Device);
+		//	break;
+
+        case VStorOperationRemoveDevice:
+
+			DPRINT_INFO(STORVSC, "REMOVE_DEVICE_OPERATION");
+			// TODO:
+			break;
+
+		default:
+			DPRINT_INFO(STORVSC, "Unknown operation received - %d", VStorPacket->Operation);
+			break;
+	}
+}
+
+void
+StorVscOnChannelCallback(
+	PVOID Context
+	)
+{
+	int ret=0;
+	DEVICE_OBJECT *device = (DEVICE_OBJECT*)Context;
+	STORVSC_DEVICE *storDevice;
+	UINT32 bytesRecvd;
+	UINT64 requestId;
+	UCHAR packet[ALIGN_UP(sizeof(VSTOR_PACKET),8)];
+	STORVSC_REQUEST_EXTENSION *request;
+
+	DPRINT_ENTER(STORVSC);
+
+	ASSERT(device);
+
+	storDevice = MustGetStorDevice(device);
+	if (!storDevice)
+	{
+		DPRINT_ERR(STORVSC, "unable to get stor device...device being destroyed?");
+		DPRINT_EXIT(STORVSC);
+		return;
+	}
+
+	do
+	{
+		ret = device->Driver->VmbusChannelInterface.RecvPacket(device,
+																packet,
+																ALIGN_UP(sizeof(VSTOR_PACKET),8),
+																&bytesRecvd,
+																&requestId);
+		if (ret == 0 && bytesRecvd > 0)
+		{
+			DPRINT_DBG(STORVSC, "receive %d bytes - tid %llx", bytesRecvd, requestId);
+
+			//ASSERT(bytesRecvd == sizeof(VSTOR_PACKET));
+
+			request = (STORVSC_REQUEST_EXTENSION*)(ULONG_PTR)requestId;
+			ASSERT(request);
+
+			//if (vstorPacket.Flags & SYNTHETIC_FLAG)
+			if ((request == &storDevice->InitRequest) || (request == &storDevice->ResetRequest))
+			{
+				//DPRINT_INFO(STORVSC, "reset completion - operation %u status %u", vstorPacket.Operation, vstorPacket.Status);
+
+				memcpy(&request->VStorPacket, packet, sizeof(VSTOR_PACKET));
+
+				WaitEventSet(request->WaitEvent);
+			}
+			else
+			{
+				StorVscOnReceive(device, (VSTOR_PACKET*)packet, request);
+			}
+		}
+		else
+		{
+			//DPRINT_DBG(STORVSC, "nothing else to read...");
+			break;
+		}
+	} while (1);
+
+	PutStorDevice(device);
+
+	DPRINT_EXIT(STORVSC);
+	return;
+}