Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1413 insertions, 0 deletions

diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
new file mode 100644
index 000000000..f0a66a344
--- /dev/null
+++ b/drivers/video/fbdev/hyperv_fb.c
@@ -0,0 +1,1413 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2012, Microsoft Corporation.
+ *
+ * Author:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ */
+
+/*
+ * Hyper-V Synthetic Video Frame Buffer Driver
+ *
+ * This is the driver for the Hyper-V Synthetic Video, which supports
+ * screen resolution up to Full HD 1920x1080 with 32 bit color on Windows
+ * Server 2012, and 1600x1200 with 16 bit color on Windows Server 2008 R2
+ * or earlier.
+ *
+ * It also solves the double mouse cursor issue of the emulated video mode.
+ *
+ * The default screen resolution is 1152x864, which may be changed by a
+ * kernel parameter:
+ *     video=hyperv_fb:<width>x<height>
+ *     For example: video=hyperv_fb:1280x1024
+ *
+ * Portrait orientation is also supported:
+ *     For example: video=hyperv_fb:864x1152
+ *
+ * When a Windows 10 RS5+ host is used, the virtual machine screen
+ * resolution is obtained from the host. The "video=hyperv_fb" option is
+ * not needed, but still can be used to overwrite what the host specifies.
+ * The VM resolution on the host could be set by executing the powershell
+ * "set-vmvideo" command. For example
+ *     set-vmvideo -vmname name -horizontalresolution:1920 \
+ * -verticalresolution:1200 -resolutiontype single
+ *
+ * Gen 1 VMs also support direct using VM's physical memory for framebuffer.
+ * It could improve the efficiency and performance for framebuffer and VM.
+ * This requires to allocate contiguous physical memory from Linux kernel's
+ * CMA memory allocator. To enable this, supply a kernel parameter to give
+ * enough memory space to CMA allocator for framebuffer. For example:
+ *    cma=130m
+ * This gives 130MB memory to CMA allocator that can be allocated to
+ * framebuffer. For reference, 8K resolution (7680x4320) takes about
+ * 127MB memory.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/vmalloc.h>
+#include <linux/init.h>
+#include <linux/completion.h>
+#include <linux/fb.h>
+#include <linux/pci.h>
+#include <linux/efi.h>
+#include <linux/console.h>
+
+#include <linux/hyperv.h>
+
+
+/* Hyper-V Synthetic Video Protocol definitions and structures */
+#define MAX_VMBUS_PKT_SIZE 0x4000
+
+#define SYNTHVID_VERSION(major, minor) ((minor) << 16 | (major))
+#define SYNTHVID_VERSION_WIN7 SYNTHVID_VERSION(3, 0)
+#define SYNTHVID_VERSION_WIN8 SYNTHVID_VERSION(3, 2)
+#define SYNTHVID_VERSION_WIN10 SYNTHVID_VERSION(3, 5)
+
+#define SYNTHVID_VER_GET_MAJOR(ver) (ver & 0x0000ffff)
+#define SYNTHVID_VER_GET_MINOR(ver) ((ver & 0xffff0000) >> 16)
+
+#define SYNTHVID_DEPTH_WIN7 16
+#define SYNTHVID_DEPTH_WIN8 32
+
+#define SYNTHVID_FB_SIZE_WIN7 (4 * 1024 * 1024)
+#define SYNTHVID_WIDTH_MAX_WIN7 1600
+#define SYNTHVID_HEIGHT_MAX_WIN7 1200
+
+#define SYNTHVID_FB_SIZE_WIN8 (8 * 1024 * 1024)
+
+#define PCI_VENDOR_ID_MICROSOFT 0x1414
+#define PCI_DEVICE_ID_HYPERV_VIDEO 0x5353
+
+
+enum pipe_msg_type {
+	PIPE_MSG_INVALID,
+	PIPE_MSG_DATA,
+	PIPE_MSG_MAX
+};
+
+struct pipe_msg_hdr {
+	u32 type;
+	u32 size; /* size of message after this field */
+} __packed;
+
+
+enum synthvid_msg_type {
+	SYNTHVID_ERROR			= 0,
+	SYNTHVID_VERSION_REQUEST	= 1,
+	SYNTHVID_VERSION_RESPONSE	= 2,
+	SYNTHVID_VRAM_LOCATION		= 3,
+	SYNTHVID_VRAM_LOCATION_ACK	= 4,
+	SYNTHVID_SITUATION_UPDATE	= 5,
+	SYNTHVID_SITUATION_UPDATE_ACK	= 6,
+	SYNTHVID_POINTER_POSITION	= 7,
+	SYNTHVID_POINTER_SHAPE		= 8,
+	SYNTHVID_FEATURE_CHANGE		= 9,
+	SYNTHVID_DIRT			= 10,
+	SYNTHVID_RESOLUTION_REQUEST	= 13,
+	SYNTHVID_RESOLUTION_RESPONSE	= 14,
+
+	SYNTHVID_MAX			= 15
+};
+
+#define		SYNTHVID_EDID_BLOCK_SIZE	128
+#define		SYNTHVID_MAX_RESOLUTION_COUNT	64
+
+struct hvd_screen_info {
+	u16 width;
+	u16 height;
+} __packed;
+
+struct synthvid_msg_hdr {
+	u32 type;
+	u32 size;  /* size of this header + payload after this field*/
+} __packed;
+
+struct synthvid_version_req {
+	u32 version;
+} __packed;
+
+struct synthvid_version_resp {
+	u32 version;
+	u8 is_accepted;
+	u8 max_video_outputs;
+} __packed;
+
+struct synthvid_supported_resolution_req {
+	u8 maximum_resolution_count;
+} __packed;
+
+struct synthvid_supported_resolution_resp {
+	u8 edid_block[SYNTHVID_EDID_BLOCK_SIZE];
+	u8 resolution_count;
+	u8 default_resolution_index;
+	u8 is_standard;
+	struct hvd_screen_info
+		supported_resolution[SYNTHVID_MAX_RESOLUTION_COUNT];
+} __packed;
+
+struct synthvid_vram_location {
+	u64 user_ctx;
+	u8 is_vram_gpa_specified;
+	u64 vram_gpa;
+} __packed;
+
+struct synthvid_vram_location_ack {
+	u64 user_ctx;
+} __packed;
+
+struct video_output_situation {
+	u8 active;
+	u32 vram_offset;
+	u8 depth_bits;
+	u32 width_pixels;
+	u32 height_pixels;
+	u32 pitch_bytes;
+} __packed;
+
+struct synthvid_situation_update {
+	u64 user_ctx;
+	u8 video_output_count;
+	struct video_output_situation video_output[1];
+} __packed;
+
+struct synthvid_situation_update_ack {
+	u64 user_ctx;
+} __packed;
+
+struct synthvid_pointer_position {
+	u8 is_visible;
+	u8 video_output;
+	s32 image_x;
+	s32 image_y;
+} __packed;
+
+
+#define CURSOR_MAX_X 96
+#define CURSOR_MAX_Y 96
+#define CURSOR_ARGB_PIXEL_SIZE 4
+#define CURSOR_MAX_SIZE (CURSOR_MAX_X * CURSOR_MAX_Y * CURSOR_ARGB_PIXEL_SIZE)
+#define CURSOR_COMPLETE (-1)
+
+struct synthvid_pointer_shape {
+	u8 part_idx;
+	u8 is_argb;
+	u32 width; /* CURSOR_MAX_X at most */
+	u32 height; /* CURSOR_MAX_Y at most */
+	u32 hot_x; /* hotspot relative to upper-left of pointer image */
+	u32 hot_y;
+	u8 data[4];
+} __packed;
+
+struct synthvid_feature_change {
+	u8 is_dirt_needed;
+	u8 is_ptr_pos_needed;
+	u8 is_ptr_shape_needed;
+	u8 is_situ_needed;
+} __packed;
+
+struct rect {
+	s32 x1, y1; /* top left corner */
+	s32 x2, y2; /* bottom right corner, exclusive */
+} __packed;
+
+struct synthvid_dirt {
+	u8 video_output;
+	u8 dirt_count;
+	struct rect rect[1];
+} __packed;
+
+struct synthvid_msg {
+	struct pipe_msg_hdr pipe_hdr;
+	struct synthvid_msg_hdr vid_hdr;
+	union {
+		struct synthvid_version_req ver_req;
+		struct synthvid_version_resp ver_resp;
+		struct synthvid_vram_location vram;
+		struct synthvid_vram_location_ack vram_ack;
+		struct synthvid_situation_update situ;
+		struct synthvid_situation_update_ack situ_ack;
+		struct synthvid_pointer_position ptr_pos;
+		struct synthvid_pointer_shape ptr_shape;
+		struct synthvid_feature_change feature_chg;
+		struct synthvid_dirt dirt;
+		struct synthvid_supported_resolution_req resolution_req;
+		struct synthvid_supported_resolution_resp resolution_resp;
+	};
+} __packed;
+
+
+/* FB driver definitions and structures */
+#define HVFB_WIDTH 1152 /* default screen width */
+#define HVFB_HEIGHT 864 /* default screen height */
+#define HVFB_WIDTH_MIN 640
+#define HVFB_HEIGHT_MIN 480
+
+#define RING_BUFSIZE (256 * 1024)
+#define VSP_TIMEOUT (10 * HZ)
+#define HVFB_UPDATE_DELAY (HZ / 20)
+#define HVFB_ONDEMAND_THROTTLE (HZ / 20)
+
+struct hvfb_par {
+	struct fb_info *info;
+	struct resource *mem;
+	bool fb_ready; /* fb device is ready */
+	struct completion wait;
+	u32 synthvid_version;
+
+	struct delayed_work dwork;
+	bool update;
+	bool update_saved; /* The value of 'update' before hibernation */
+
+	u32 pseudo_palette[16];
+	u8 init_buf[MAX_VMBUS_PKT_SIZE];
+	u8 recv_buf[MAX_VMBUS_PKT_SIZE];
+
+	/* If true, the VSC notifies the VSP on every framebuffer change */
+	bool synchronous_fb;
+
+	/* If true, need to copy from deferred IO mem to framebuffer mem */
+	bool need_docopy;
+
+	struct notifier_block hvfb_panic_nb;
+
+	/* Memory for deferred IO and frame buffer itself */
+	unsigned char *dio_vp;
+	unsigned char *mmio_vp;
+	phys_addr_t mmio_pp;
+
+	/* Dirty rectangle, protected by delayed_refresh_lock */
+	int x1, y1, x2, y2;
+	bool delayed_refresh;
+	spinlock_t delayed_refresh_lock;
+};
+
+static uint screen_width = HVFB_WIDTH;
+static uint screen_height = HVFB_HEIGHT;
+static uint screen_depth;
+static uint screen_fb_size;
+static uint dio_fb_size; /* FB size for deferred IO */
+
+/* Send message to Hyper-V host */
+static inline int synthvid_send(struct hv_device *hdev,
+				struct synthvid_msg *msg)
+{
+	static atomic64_t request_id = ATOMIC64_INIT(0);
+	int ret;
+
+	msg->pipe_hdr.type = PIPE_MSG_DATA;
+	msg->pipe_hdr.size = msg->vid_hdr.size;
+
+	ret = vmbus_sendpacket(hdev->channel, msg,
+			       msg->vid_hdr.size + sizeof(struct pipe_msg_hdr),
+			       atomic64_inc_return(&request_id),
+			       VM_PKT_DATA_INBAND, 0);
+
+	if (ret)
+		pr_err("Unable to send packet via vmbus\n");
+
+	return ret;
+}
+
+
+/* Send screen resolution info to host */
+static int synthvid_send_situ(struct hv_device *hdev)
+{
+	struct fb_info *info = hv_get_drvdata(hdev);
+	struct synthvid_msg msg;
+
+	if (!info)
+		return -ENODEV;
+
+	memset(&msg, 0, sizeof(struct synthvid_msg));
+
+	msg.vid_hdr.type = SYNTHVID_SITUATION_UPDATE;
+	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_situation_update);
+	msg.situ.user_ctx = 0;
+	msg.situ.video_output_count = 1;
+	msg.situ.video_output[0].active = 1;
+	msg.situ.video_output[0].vram_offset = 0;
+	msg.situ.video_output[0].depth_bits = info->var.bits_per_pixel;
+	msg.situ.video_output[0].width_pixels = info->var.xres;
+	msg.situ.video_output[0].height_pixels = info->var.yres;
+	msg.situ.video_output[0].pitch_bytes = info->fix.line_length;
+
+	synthvid_send(hdev, &msg);
+
+	return 0;
+}
+
+/* Send mouse pointer info to host */
+static int synthvid_send_ptr(struct hv_device *hdev)
+{
+	struct synthvid_msg msg;
+
+	memset(&msg, 0, sizeof(struct synthvid_msg));
+	msg.vid_hdr.type = SYNTHVID_POINTER_POSITION;
+	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_pointer_position);
+	msg.ptr_pos.is_visible = 1;
+	msg.ptr_pos.video_output = 0;
+	msg.ptr_pos.image_x = 0;
+	msg.ptr_pos.image_y = 0;
+	synthvid_send(hdev, &msg);
+
+	memset(&msg, 0, sizeof(struct synthvid_msg));
+	msg.vid_hdr.type = SYNTHVID_POINTER_SHAPE;
+	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_pointer_shape);
+	msg.ptr_shape.part_idx = CURSOR_COMPLETE;
+	msg.ptr_shape.is_argb = 1;
+	msg.ptr_shape.width = 1;
+	msg.ptr_shape.height = 1;
+	msg.ptr_shape.hot_x = 0;
+	msg.ptr_shape.hot_y = 0;
+	msg.ptr_shape.data[0] = 0;
+	msg.ptr_shape.data[1] = 1;
+	msg.ptr_shape.data[2] = 1;
+	msg.ptr_shape.data[3] = 1;
+	synthvid_send(hdev, &msg);
+
+	return 0;
+}
+
+/* Send updated screen area (dirty rectangle) location to host */
+static int
+synthvid_update(struct fb_info *info, int x1, int y1, int x2, int y2)
+{
+	struct hv_device *hdev = device_to_hv_device(info->device);
+	struct synthvid_msg msg;
+
+	memset(&msg, 0, sizeof(struct synthvid_msg));
+	if (x2 == INT_MAX)
+		x2 = info->var.xres;
+	if (y2 == INT_MAX)
+		y2 = info->var.yres;
+
+	msg.vid_hdr.type = SYNTHVID_DIRT;
+	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_dirt);
+	msg.dirt.video_output = 0;
+	msg.dirt.dirt_count = 1;
+	msg.dirt.rect[0].x1 = (x1 > x2) ? 0 : x1;
+	msg.dirt.rect[0].y1 = (y1 > y2) ? 0 : y1;
+	msg.dirt.rect[0].x2 =
+		(x2 < x1 || x2 > info->var.xres) ? info->var.xres : x2;
+	msg.dirt.rect[0].y2 =
+		(y2 < y1 || y2 > info->var.yres) ? info->var.yres : y2;
+
+	synthvid_send(hdev, &msg);
+
+	return 0;
+}
+
+static void hvfb_docopy(struct hvfb_par *par,
+			unsigned long offset,
+			unsigned long size)
+{
+	if (!par || !par->mmio_vp || !par->dio_vp || !par->fb_ready ||
+	    size == 0 || offset >= dio_fb_size)
+		return;
+
+	if (offset + size > dio_fb_size)
+		size = dio_fb_size - offset;
+
+	memcpy(par->mmio_vp + offset, par->dio_vp + offset, size);
+}
+
+/* Deferred IO callback */
+static void synthvid_deferred_io(struct fb_info *p,
+				 struct list_head *pagelist)
+{
+	struct hvfb_par *par = p->par;
+	struct page *page;
+	unsigned long start, end;
+	int y1, y2, miny, maxy;
+
+	miny = INT_MAX;
+	maxy = 0;
+
+	/*
+	 * Merge dirty pages. It is possible that last page cross
+	 * over the end of frame buffer row yres. This is taken care of
+	 * in synthvid_update function by clamping the y2
+	 * value to yres.
+	 */
+	list_for_each_entry(page, pagelist, lru) {
+		start = page->index << PAGE_SHIFT;
+		end = start + PAGE_SIZE - 1;
+		y1 = start / p->fix.line_length;
+		y2 = end / p->fix.line_length;
+		miny = min_t(int, miny, y1);
+		maxy = max_t(int, maxy, y2);
+
+		/* Copy from dio space to mmio address */
+		if (par->fb_ready && par->need_docopy)
+			hvfb_docopy(par, start, PAGE_SIZE);
+	}
+
+	if (par->fb_ready && par->update)
+		synthvid_update(p, 0, miny, p->var.xres, maxy + 1);
+}
+
+static struct fb_deferred_io synthvid_defio = {
+	.delay		= HZ / 20,
+	.deferred_io	= synthvid_deferred_io,
+};
+
+/*
+ * Actions on received messages from host:
+ * Complete the wait event.
+ * Or, reply with screen and cursor info.
+ */
+static void synthvid_recv_sub(struct hv_device *hdev)
+{
+	struct fb_info *info = hv_get_drvdata(hdev);
+	struct hvfb_par *par;
+	struct synthvid_msg *msg;
+
+	if (!info)
+		return;
+
+	par = info->par;
+	msg = (struct synthvid_msg *)par->recv_buf;
+
+	/* Complete the wait event */
+	if (msg->vid_hdr.type == SYNTHVID_VERSION_RESPONSE ||
+	    msg->vid_hdr.type == SYNTHVID_RESOLUTION_RESPONSE ||
+	    msg->vid_hdr.type == SYNTHVID_VRAM_LOCATION_ACK) {
+		memcpy(par->init_buf, msg, MAX_VMBUS_PKT_SIZE);
+		complete(&par->wait);
+		return;
+	}
+
+	/* Reply with screen and cursor info */
+	if (msg->vid_hdr.type == SYNTHVID_FEATURE_CHANGE) {
+		if (par->fb_ready) {
+			synthvid_send_ptr(hdev);
+			synthvid_send_situ(hdev);
+		}
+
+		par->update = msg->feature_chg.is_dirt_needed;
+		if (par->update)
+			schedule_delayed_work(&par->dwork, HVFB_UPDATE_DELAY);
+	}
+}
+
+/* Receive callback for messages from the host */
+static void synthvid_receive(void *ctx)
+{
+	struct hv_device *hdev = ctx;
+	struct fb_info *info = hv_get_drvdata(hdev);
+	struct hvfb_par *par;
+	struct synthvid_msg *recv_buf;
+	u32 bytes_recvd;
+	u64 req_id;
+	int ret;
+
+	if (!info)
+		return;
+
+	par = info->par;
+	recv_buf = (struct synthvid_msg *)par->recv_buf;
+
+	do {
+		ret = vmbus_recvpacket(hdev->channel, recv_buf,
+				       MAX_VMBUS_PKT_SIZE,
+				       &bytes_recvd, &req_id);
+		if (bytes_recvd > 0 &&
+		    recv_buf->pipe_hdr.type == PIPE_MSG_DATA)
+			synthvid_recv_sub(hdev);
+	} while (bytes_recvd > 0 && ret == 0);
+}
+
+/* Check if the ver1 version is equal or greater than ver2 */
+static inline bool synthvid_ver_ge(u32 ver1, u32 ver2)
+{
+	if (SYNTHVID_VER_GET_MAJOR(ver1) > SYNTHVID_VER_GET_MAJOR(ver2) ||
+	    (SYNTHVID_VER_GET_MAJOR(ver1) == SYNTHVID_VER_GET_MAJOR(ver2) &&
+	     SYNTHVID_VER_GET_MINOR(ver1) >= SYNTHVID_VER_GET_MINOR(ver2)))
+		return true;
+
+	return false;
+}
+
+/* Check synthetic video protocol version with the host */
+static int synthvid_negotiate_ver(struct hv_device *hdev, u32 ver)
+{
+	struct fb_info *info = hv_get_drvdata(hdev);
+	struct hvfb_par *par = info->par;
+	struct synthvid_msg *msg = (struct synthvid_msg *)par->init_buf;
+	int ret = 0;
+	unsigned long t;
+
+	memset(msg, 0, sizeof(struct synthvid_msg));
+	msg->vid_hdr.type = SYNTHVID_VERSION_REQUEST;
+	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_version_req);
+	msg->ver_req.version = ver;
+	synthvid_send(hdev, msg);
+
+	t = wait_for_completion_timeout(&par->wait, VSP_TIMEOUT);
+	if (!t) {
+		pr_err("Time out on waiting version response\n");
+		ret = -ETIMEDOUT;
+		goto out;
+	}
+	if (!msg->ver_resp.is_accepted) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	par->synthvid_version = ver;
+	pr_info("Synthvid Version major %d, minor %d\n",
+		SYNTHVID_VER_GET_MAJOR(ver), SYNTHVID_VER_GET_MINOR(ver));
+
+out:
+	return ret;
+}
+
+/* Get current resolution from the host */
+static int synthvid_get_supported_resolution(struct hv_device *hdev)
+{
+	struct fb_info *info = hv_get_drvdata(hdev);
+	struct hvfb_par *par = info->par;
+	struct synthvid_msg *msg = (struct synthvid_msg *)par->init_buf;
+	int ret = 0;
+	unsigned long t;
+	u8 index;
+
+	memset(msg, 0, sizeof(struct synthvid_msg));
+	msg->vid_hdr.type = SYNTHVID_RESOLUTION_REQUEST;
+	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_supported_resolution_req);
+
+	msg->resolution_req.maximum_resolution_count =
+		SYNTHVID_MAX_RESOLUTION_COUNT;
+	synthvid_send(hdev, msg);
+
+	t = wait_for_completion_timeout(&par->wait, VSP_TIMEOUT);
+	if (!t) {
+		pr_err("Time out on waiting resolution response\n");
+		ret = -ETIMEDOUT;
+		goto out;
+	}
+
+	if (msg->resolution_resp.resolution_count == 0) {
+		pr_err("No supported resolutions\n");
+		ret = -ENODEV;
+		goto out;
+	}
+
+	index = msg->resolution_resp.default_resolution_index;
+	if (index >= msg->resolution_resp.resolution_count) {
+		pr_err("Invalid resolution index: %d\n", index);
+		ret = -ENODEV;
+		goto out;
+	}
+
+	screen_width =
+		msg->resolution_resp.supported_resolution[index].width;
+	screen_height =
+		msg->resolution_resp.supported_resolution[index].height;
+
+out:
+	return ret;
+}
+
+/* Connect to VSP (Virtual Service Provider) on host */
+static int synthvid_connect_vsp(struct hv_device *hdev)
+{
+	struct fb_info *info = hv_get_drvdata(hdev);
+	struct hvfb_par *par = info->par;
+	int ret;
+
+	ret = vmbus_open(hdev->channel, RING_BUFSIZE, RING_BUFSIZE,
+			 NULL, 0, synthvid_receive, hdev);
+	if (ret) {
+		pr_err("Unable to open vmbus channel\n");
+		return ret;
+	}
+
+	/* Negotiate the protocol version with host */
+	switch (vmbus_proto_version) {
+	case VERSION_WIN10:
+	case VERSION_WIN10_V5:
+		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN10);
+		if (!ret)
+			break;
+		fallthrough;
+	case VERSION_WIN8:
+	case VERSION_WIN8_1:
+		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN8);
+		if (!ret)
+			break;
+		fallthrough;
+	case VERSION_WS2008:
+	case VERSION_WIN7:
+		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN7);
+		break;
+	default:
+		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN10);
+		break;
+	}
+
+	if (ret) {
+		pr_err("Synthetic video device version not accepted\n");
+		goto error;
+	}
+
+	if (par->synthvid_version == SYNTHVID_VERSION_WIN7)
+		screen_depth = SYNTHVID_DEPTH_WIN7;
+	else
+		screen_depth = SYNTHVID_DEPTH_WIN8;
+
+	if (synthvid_ver_ge(par->synthvid_version, SYNTHVID_VERSION_WIN10)) {
+		ret = synthvid_get_supported_resolution(hdev);
+		if (ret)
+			pr_info("Failed to get supported resolution from host, use default\n");
+	}
+
+	screen_fb_size = hdev->channel->offermsg.offer.
+				mmio_megabytes * 1024 * 1024;
+
+	return 0;
+
+error:
+	vmbus_close(hdev->channel);
+	return ret;
+}
+
+/* Send VRAM and Situation messages to the host */
+static int synthvid_send_config(struct hv_device *hdev)
+{
+	struct fb_info *info = hv_get_drvdata(hdev);
+	struct hvfb_par *par = info->par;
+	struct synthvid_msg *msg = (struct synthvid_msg *)par->init_buf;
+	int ret = 0;
+	unsigned long t;
+
+	/* Send VRAM location */
+	memset(msg, 0, sizeof(struct synthvid_msg));
+	msg->vid_hdr.type = SYNTHVID_VRAM_LOCATION;
+	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_vram_location);
+	msg->vram.user_ctx = msg->vram.vram_gpa = par->mmio_pp;
+	msg->vram.is_vram_gpa_specified = 1;
+	synthvid_send(hdev, msg);
+
+	t = wait_for_completion_timeout(&par->wait, VSP_TIMEOUT);
+	if (!t) {
+		pr_err("Time out on waiting vram location ack\n");
+		ret = -ETIMEDOUT;
+		goto out;
+	}
+	if (msg->vram_ack.user_ctx != par->mmio_pp) {
+		pr_err("Unable to set VRAM location\n");
+		ret = -ENODEV;
+		goto out;
+	}
+
+	/* Send pointer and situation update */
+	synthvid_send_ptr(hdev);
+	synthvid_send_situ(hdev);
+
+out:
+	return ret;
+}
+
+
+/*
+ * Delayed work callback:
+ * It is scheduled to call whenever update request is received and it has
+ * not been called in last HVFB_ONDEMAND_THROTTLE time interval.
+ */
+static void hvfb_update_work(struct work_struct *w)
+{
+	struct hvfb_par *par = container_of(w, struct hvfb_par, dwork.work);
+	struct fb_info *info = par->info;
+	unsigned long flags;
+	int x1, x2, y1, y2;
+	int j;
+
+	spin_lock_irqsave(&par->delayed_refresh_lock, flags);
+	/* Reset the request flag */
+	par->delayed_refresh = false;
+
+	/* Store the dirty rectangle to local variables */
+	x1 = par->x1;
+	x2 = par->x2;
+	y1 = par->y1;
+	y2 = par->y2;
+
+	/* Clear dirty rectangle */
+	par->x1 = par->y1 = INT_MAX;
+	par->x2 = par->y2 = 0;
+
+	spin_unlock_irqrestore(&par->delayed_refresh_lock, flags);
+
+	if (x1 > info->var.xres || x2 > info->var.xres ||
+	    y1 > info->var.yres || y2 > info->var.yres || x2 <= x1)
+		return;
+
+	/* Copy the dirty rectangle to frame buffer memory */
+	if (par->need_docopy)
+		for (j = y1; j < y2; j++)
+			hvfb_docopy(par,
+				    j * info->fix.line_length +
+				    (x1 * screen_depth / 8),
+				    (x2 - x1) * screen_depth / 8);
+
+	/* Refresh */
+	if (par->fb_ready && par->update)
+		synthvid_update(info, x1, y1, x2, y2);
+}
+
+/*
+ * Control the on-demand refresh frequency. It schedules a delayed
+ * screen update if it has not yet.
+ */
+static void hvfb_ondemand_refresh_throttle(struct hvfb_par *par,
+					   int x1, int y1, int w, int h)
+{
+	unsigned long flags;
+	int x2 = x1 + w;
+	int y2 = y1 + h;
+
+	spin_lock_irqsave(&par->delayed_refresh_lock, flags);
+
+	/* Merge dirty rectangle */
+	par->x1 = min_t(int, par->x1, x1);
+	par->y1 = min_t(int, par->y1, y1);
+	par->x2 = max_t(int, par->x2, x2);
+	par->y2 = max_t(int, par->y2, y2);
+
+	/* Schedule a delayed screen update if not yet */
+	if (par->delayed_refresh == false) {
+		schedule_delayed_work(&par->dwork,
+				      HVFB_ONDEMAND_THROTTLE);
+		par->delayed_refresh = true;
+	}
+
+	spin_unlock_irqrestore(&par->delayed_refresh_lock, flags);
+}
+
+static int hvfb_on_panic(struct notifier_block *nb,
+			 unsigned long e, void *p)
+{
+	struct hv_device *hdev;
+	struct hvfb_par *par;
+	struct fb_info *info;
+
+	par = container_of(nb, struct hvfb_par, hvfb_panic_nb);
+	info = par->info;
+	hdev = device_to_hv_device(info->device);
+
+	if (hv_ringbuffer_spinlock_busy(hdev->channel))
+		return NOTIFY_DONE;
+
+	par->synchronous_fb = true;
+	if (par->need_docopy)
+		hvfb_docopy(par, 0, dio_fb_size);
+	synthvid_update(info, 0, 0, INT_MAX, INT_MAX);
+
+	return NOTIFY_DONE;
+}
+
+/* Framebuffer operation handlers */
+
+static int hvfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
+{
+	if (var->xres < HVFB_WIDTH_MIN || var->yres < HVFB_HEIGHT_MIN ||
+	    var->xres > screen_width || var->yres >  screen_height ||
+	    var->bits_per_pixel != screen_depth)
+		return -EINVAL;
+
+	var->xres_virtual = var->xres;
+	var->yres_virtual = var->yres;
+
+	return 0;
+}
+
+static int hvfb_set_par(struct fb_info *info)
+{
+	struct hv_device *hdev = device_to_hv_device(info->device);
+
+	return synthvid_send_situ(hdev);
+}
+
+
+static inline u32 chan_to_field(u32 chan, struct fb_bitfield *bf)
+{
+	return ((chan & 0xffff) >> (16 - bf->length)) << bf->offset;
+}
+
+static int hvfb_setcolreg(unsigned regno, unsigned red, unsigned green,
+			  unsigned blue, unsigned transp, struct fb_info *info)
+{
+	u32 *pal = info->pseudo_palette;
+
+	if (regno > 15)
+		return -EINVAL;
+
+	pal[regno] = chan_to_field(red, &info->var.red)
+		| chan_to_field(green, &info->var.green)
+		| chan_to_field(blue, &info->var.blue)
+		| chan_to_field(transp, &info->var.transp);
+
+	return 0;
+}
+
+static int hvfb_blank(int blank, struct fb_info *info)
+{
+	return 1;	/* get fb_blank to set the colormap to all black */
+}
+
+static void hvfb_cfb_fillrect(struct fb_info *p,
+			      const struct fb_fillrect *rect)
+{
+	struct hvfb_par *par = p->par;
+
+	cfb_fillrect(p, rect);
+	if (par->synchronous_fb)
+		synthvid_update(p, 0, 0, INT_MAX, INT_MAX);
+	else
+		hvfb_ondemand_refresh_throttle(par, rect->dx, rect->dy,
+					       rect->width, rect->height);
+}
+
+static void hvfb_cfb_copyarea(struct fb_info *p,
+			      const struct fb_copyarea *area)
+{
+	struct hvfb_par *par = p->par;
+
+	cfb_copyarea(p, area);
+	if (par->synchronous_fb)
+		synthvid_update(p, 0, 0, INT_MAX, INT_MAX);
+	else
+		hvfb_ondemand_refresh_throttle(par, area->dx, area->dy,
+					       area->width, area->height);
+}
+
+static void hvfb_cfb_imageblit(struct fb_info *p,
+			       const struct fb_image *image)
+{
+	struct hvfb_par *par = p->par;
+
+	cfb_imageblit(p, image);
+	if (par->synchronous_fb)
+		synthvid_update(p, 0, 0, INT_MAX, INT_MAX);
+	else
+		hvfb_ondemand_refresh_throttle(par, image->dx, image->dy,
+					       image->width, image->height);
+}
+
+static const struct fb_ops hvfb_ops = {
+	.owner = THIS_MODULE,
+	.fb_check_var = hvfb_check_var,
+	.fb_set_par = hvfb_set_par,
+	.fb_setcolreg = hvfb_setcolreg,
+	.fb_fillrect = hvfb_cfb_fillrect,
+	.fb_copyarea = hvfb_cfb_copyarea,
+	.fb_imageblit = hvfb_cfb_imageblit,
+	.fb_blank = hvfb_blank,
+};
+
+
+/* Get options from kernel paramenter "video=" */
+static void hvfb_get_option(struct fb_info *info)
+{
+	struct hvfb_par *par = info->par;
+	char *opt = NULL, *p;
+	uint x = 0, y = 0;
+
+	if (fb_get_options(KBUILD_MODNAME, &opt) || !opt || !*opt)
+		return;
+
+	p = strsep(&opt, "x");
+	if (!*p || kstrtouint(p, 0, &x) ||
+	    !opt || !*opt || kstrtouint(opt, 0, &y)) {
+		pr_err("Screen option is invalid: skipped\n");
+		return;
+	}
+
+	if (x < HVFB_WIDTH_MIN || y < HVFB_HEIGHT_MIN ||
+	    (synthvid_ver_ge(par->synthvid_version, SYNTHVID_VERSION_WIN10) &&
+	    (x * y * screen_depth / 8 > screen_fb_size)) ||
+	    (par->synthvid_version == SYNTHVID_VERSION_WIN8 &&
+	     x * y * screen_depth / 8 > SYNTHVID_FB_SIZE_WIN8) ||
+	    (par->synthvid_version == SYNTHVID_VERSION_WIN7 &&
+	     (x > SYNTHVID_WIDTH_MAX_WIN7 || y > SYNTHVID_HEIGHT_MAX_WIN7))) {
+		pr_err("Screen resolution option is out of range: skipped\n");
+		return;
+	}
+
+	screen_width = x;
+	screen_height = y;
+	return;
+}
+
+/*
+ * Allocate enough contiguous physical memory.
+ * Return physical address if succeeded or -1 if failed.
+ */
+static phys_addr_t hvfb_get_phymem(struct hv_device *hdev,
+				   unsigned int request_size)
+{
+	struct page *page = NULL;
+	dma_addr_t dma_handle;
+	void *vmem;
+	phys_addr_t paddr = 0;
+	unsigned int order = get_order(request_size);
+
+	if (request_size == 0)
+		return -1;
+
+	if (order < MAX_ORDER) {
+		/* Call alloc_pages if the size is less than 2^MAX_ORDER */
+		page = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
+		if (!page)
+			return -1;
+
+		paddr = (page_to_pfn(page) << PAGE_SHIFT);
+	} else {
+		/* Allocate from CMA */
+		hdev->device.coherent_dma_mask = DMA_BIT_MASK(64);
+
+		vmem = dma_alloc_coherent(&hdev->device,
+					  round_up(request_size, PAGE_SIZE),
+					  &dma_handle,
+					  GFP_KERNEL | __GFP_NOWARN);
+
+		if (!vmem)
+			return -1;
+
+		paddr = virt_to_phys(vmem);
+	}
+
+	return paddr;
+}
+
+/* Release contiguous physical memory */
+static void hvfb_release_phymem(struct hv_device *hdev,
+				phys_addr_t paddr, unsigned int size)
+{
+	unsigned int order = get_order(size);
+
+	if (order < MAX_ORDER)
+		__free_pages(pfn_to_page(paddr >> PAGE_SHIFT), order);
+	else
+		dma_free_coherent(&hdev->device,
+				  round_up(size, PAGE_SIZE),
+				  phys_to_virt(paddr),
+				  paddr);
+}
+
+
+/* Get framebuffer memory from Hyper-V video pci space */
+static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info)
+{
+	struct hvfb_par *par = info->par;
+	struct pci_dev *pdev  = NULL;
+	void __iomem *fb_virt;
+	int gen2vm = efi_enabled(EFI_BOOT);
+	phys_addr_t paddr;
+	int ret;
+
+	info->apertures = alloc_apertures(1);
+	if (!info->apertures)
+		return -ENOMEM;
+
+	if (!gen2vm) {
+		pdev = pci_get_device(PCI_VENDOR_ID_MICROSOFT,
+			PCI_DEVICE_ID_HYPERV_VIDEO, NULL);
+		if (!pdev) {
+			pr_err("Unable to find PCI Hyper-V video\n");
+			return -ENODEV;
+		}
+
+		info->apertures->ranges[0].base = pci_resource_start(pdev, 0);
+		info->apertures->ranges[0].size = pci_resource_len(pdev, 0);
+
+		/*
+		 * For Gen 1 VM, we can directly use the contiguous memory
+		 * from VM. If we succeed, deferred IO happens directly
+		 * on this allocated framebuffer memory, avoiding extra
+		 * memory copy.
+		 */
+		paddr = hvfb_get_phymem(hdev, screen_fb_size);
+		if (paddr != (phys_addr_t) -1) {
+			par->mmio_pp = paddr;
+			par->mmio_vp = par->dio_vp = __va(paddr);
+
+			info->fix.smem_start = paddr;
+			info->fix.smem_len = screen_fb_size;
+			info->screen_base = par->mmio_vp;
+			info->screen_size = screen_fb_size;
+
+			par->need_docopy = false;
+			goto getmem_done;
+		}
+		pr_info("Unable to allocate enough contiguous physical memory on Gen 1 VM. Using MMIO instead.\n");
+	} else {
+		info->apertures->ranges[0].base = screen_info.lfb_base;
+		info->apertures->ranges[0].size = screen_info.lfb_size;
+	}
+
+	/*
+	 * Cannot use the contiguous physical memory.
+	 * Allocate mmio space for framebuffer.
+	 */
+	dio_fb_size =
+		screen_width * screen_height * screen_depth / 8;
+
+	ret = vmbus_allocate_mmio(&par->mem, hdev, 0, -1,
+				  screen_fb_size, 0x100000, true);
+	if (ret != 0) {
+		pr_err("Unable to allocate framebuffer memory\n");
+		goto err1;
+	}
+
+	/*
+	 * Map the VRAM cacheable for performance. This is also required for
+	 * VM Connect to display properly for ARM64 Linux VM, as the host also
+	 * maps the VRAM cacheable.
+	 */
+	fb_virt = ioremap_cache(par->mem->start, screen_fb_size);
+	if (!fb_virt)
+		goto err2;
+
+	/* Allocate memory for deferred IO */
+	par->dio_vp = vzalloc(round_up(dio_fb_size, PAGE_SIZE));
+	if (par->dio_vp == NULL)
+		goto err3;
+
+	/* Physical address of FB device */
+	par->mmio_pp = par->mem->start;
+	/* Virtual address of FB device */
+	par->mmio_vp = (unsigned char *) fb_virt;
+
+	info->fix.smem_start = par->mem->start;
+	info->fix.smem_len = dio_fb_size;
+	info->screen_base = par->dio_vp;
+	info->screen_size = dio_fb_size;
+
+getmem_done:
+	remove_conflicting_framebuffers(info->apertures,
+					KBUILD_MODNAME, false);
+
+	if (gen2vm) {
+		/* framebuffer is reallocated, clear screen_info to avoid misuse from kexec */
+		screen_info.lfb_size = 0;
+		screen_info.lfb_base = 0;
+		screen_info.orig_video_isVGA = 0;
+	} else {
+		pci_dev_put(pdev);
+	}
+
+	return 0;
+
+err3:
+	iounmap(fb_virt);
+err2:
+	vmbus_free_mmio(par->mem->start, screen_fb_size);
+	par->mem = NULL;
+err1:
+	if (!gen2vm)
+		pci_dev_put(pdev);
+
+	return -ENOMEM;
+}
+
+/* Release the framebuffer */
+static void hvfb_putmem(struct hv_device *hdev, struct fb_info *info)
+{
+	struct hvfb_par *par = info->par;
+
+	if (par->need_docopy) {
+		vfree(par->dio_vp);
+		iounmap(info->screen_base);
+		vmbus_free_mmio(par->mem->start, screen_fb_size);
+	} else {
+		hvfb_release_phymem(hdev, info->fix.smem_start,
+				    screen_fb_size);
+	}
+
+	par->mem = NULL;
+}
+
+
+static int hvfb_probe(struct hv_device *hdev,
+		      const struct hv_vmbus_device_id *dev_id)
+{
+	struct fb_info *info;
+	struct hvfb_par *par;
+	int ret;
+
+	info = framebuffer_alloc(sizeof(struct hvfb_par), &hdev->device);
+	if (!info)
+		return -ENOMEM;
+
+	par = info->par;
+	par->info = info;
+	par->fb_ready = false;
+	par->need_docopy = true;
+	init_completion(&par->wait);
+	INIT_DELAYED_WORK(&par->dwork, hvfb_update_work);
+
+	par->delayed_refresh = false;
+	spin_lock_init(&par->delayed_refresh_lock);
+	par->x1 = par->y1 = INT_MAX;
+	par->x2 = par->y2 = 0;
+
+	/* Connect to VSP */
+	hv_set_drvdata(hdev, info);
+	ret = synthvid_connect_vsp(hdev);
+	if (ret) {
+		pr_err("Unable to connect to VSP\n");
+		goto error1;
+	}
+
+	hvfb_get_option(info);
+	pr_info("Screen resolution: %dx%d, Color depth: %d, Frame buffer size: %d\n",
+		screen_width, screen_height, screen_depth, screen_fb_size);
+
+	ret = hvfb_getmem(hdev, info);
+	if (ret) {
+		pr_err("No memory for framebuffer\n");
+		goto error2;
+	}
+
+	/* Set up fb_info */
+	info->flags = FBINFO_DEFAULT;
+
+	info->var.xres_virtual = info->var.xres = screen_width;
+	info->var.yres_virtual = info->var.yres = screen_height;
+	info->var.bits_per_pixel = screen_depth;
+
+	if (info->var.bits_per_pixel == 16) {
+		info->var.red = (struct fb_bitfield){11, 5, 0};
+		info->var.green = (struct fb_bitfield){5, 6, 0};
+		info->var.blue = (struct fb_bitfield){0, 5, 0};
+		info->var.transp = (struct fb_bitfield){0, 0, 0};
+	} else {
+		info->var.red = (struct fb_bitfield){16, 8, 0};
+		info->var.green = (struct fb_bitfield){8, 8, 0};
+		info->var.blue = (struct fb_bitfield){0, 8, 0};
+		info->var.transp = (struct fb_bitfield){24, 8, 0};
+	}
+
+	info->var.activate = FB_ACTIVATE_NOW;
+	info->var.height = -1;
+	info->var.width = -1;
+	info->var.vmode = FB_VMODE_NONINTERLACED;
+
+	strcpy(info->fix.id, KBUILD_MODNAME);
+	info->fix.type = FB_TYPE_PACKED_PIXELS;
+	info->fix.visual = FB_VISUAL_TRUECOLOR;
+	info->fix.line_length = screen_width * screen_depth / 8;
+	info->fix.accel = FB_ACCEL_NONE;
+
+	info->fbops = &hvfb_ops;
+	info->pseudo_palette = par->pseudo_palette;
+
+	/* Initialize deferred IO */
+	info->fbdefio = &synthvid_defio;
+	fb_deferred_io_init(info);
+
+	/* Send config to host */
+	ret = synthvid_send_config(hdev);
+	if (ret)
+		goto error;
+
+	ret = register_framebuffer(info);
+	if (ret) {
+		pr_err("Unable to register framebuffer\n");
+		goto error;
+	}
+
+	par->fb_ready = true;
+
+	par->synchronous_fb = false;
+	par->hvfb_panic_nb.notifier_call = hvfb_on_panic;
+	atomic_notifier_chain_register(&panic_notifier_list,
+				       &par->hvfb_panic_nb);
+
+	return 0;
+
+error:
+	fb_deferred_io_cleanup(info);
+	hvfb_putmem(hdev, info);
+error2:
+	vmbus_close(hdev->channel);
+error1:
+	cancel_delayed_work_sync(&par->dwork);
+	hv_set_drvdata(hdev, NULL);
+	framebuffer_release(info);
+	return ret;
+}
+
+
+static int hvfb_remove(struct hv_device *hdev)
+{
+	struct fb_info *info = hv_get_drvdata(hdev);
+	struct hvfb_par *par = info->par;
+
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+					 &par->hvfb_panic_nb);
+
+	par->update = false;
+	par->fb_ready = false;
+
+	fb_deferred_io_cleanup(info);
+
+	unregister_framebuffer(info);
+	cancel_delayed_work_sync(&par->dwork);
+
+	vmbus_close(hdev->channel);
+	hv_set_drvdata(hdev, NULL);
+
+	hvfb_putmem(hdev, info);
+	framebuffer_release(info);
+
+	return 0;
+}
+
+static int hvfb_suspend(struct hv_device *hdev)
+{
+	struct fb_info *info = hv_get_drvdata(hdev);
+	struct hvfb_par *par = info->par;
+
+	console_lock();
+
+	/* 1 means do suspend */
+	fb_set_suspend(info, 1);
+
+	cancel_delayed_work_sync(&par->dwork);
+	cancel_delayed_work_sync(&info->deferred_work);
+
+	par->update_saved = par->update;
+	par->update = false;
+	par->fb_ready = false;
+
+	vmbus_close(hdev->channel);
+
+	console_unlock();
+
+	return 0;
+}
+
+static int hvfb_resume(struct hv_device *hdev)
+{
+	struct fb_info *info = hv_get_drvdata(hdev);
+	struct hvfb_par *par = info->par;
+	int ret;
+
+	console_lock();
+
+	ret = synthvid_connect_vsp(hdev);
+	if (ret != 0)
+		goto out;
+
+	ret = synthvid_send_config(hdev);
+	if (ret != 0) {
+		vmbus_close(hdev->channel);
+		goto out;
+	}
+
+	par->fb_ready = true;
+	par->update = par->update_saved;
+
+	schedule_delayed_work(&info->deferred_work, info->fbdefio->delay);
+	schedule_delayed_work(&par->dwork, HVFB_UPDATE_DELAY);
+
+	/* 0 means do resume */
+	fb_set_suspend(info, 0);
+
+out:
+	console_unlock();
+
+	return ret;
+}
+
+
+static const struct pci_device_id pci_stub_id_table[] = {
+	{
+		.vendor      = PCI_VENDOR_ID_MICROSOFT,
+		.device      = PCI_DEVICE_ID_HYPERV_VIDEO,
+	},
+	{ /* end of list */ }
+};
+
+static const struct hv_vmbus_device_id id_table[] = {
+	/* Synthetic Video Device GUID */
+	{HV_SYNTHVID_GUID},
+	{}
+};
+
+MODULE_DEVICE_TABLE(pci, pci_stub_id_table);
+MODULE_DEVICE_TABLE(vmbus, id_table);
+
+static struct hv_driver hvfb_drv = {
+	.name = KBUILD_MODNAME,
+	.id_table = id_table,
+	.probe = hvfb_probe,
+	.remove = hvfb_remove,
+	.suspend = hvfb_suspend,
+	.resume = hvfb_resume,
+	.driver = {
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+};
+
+static int hvfb_pci_stub_probe(struct pci_dev *pdev,
+			       const struct pci_device_id *ent)
+{
+	return 0;
+}
+
+static void hvfb_pci_stub_remove(struct pci_dev *pdev)
+{
+}
+
+static struct pci_driver hvfb_pci_stub_driver = {
+	.name =		KBUILD_MODNAME,
+	.id_table =	pci_stub_id_table,
+	.probe =	hvfb_pci_stub_probe,
+	.remove =	hvfb_pci_stub_remove,
+	.driver = {
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	}
+};
+
+static int __init hvfb_drv_init(void)
+{
+	int ret;
+
+	ret = vmbus_driver_register(&hvfb_drv);
+	if (ret != 0)
+		return ret;
+
+	ret = pci_register_driver(&hvfb_pci_stub_driver);
+	if (ret != 0) {
+		vmbus_driver_unregister(&hvfb_drv);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void __exit hvfb_drv_exit(void)
+{
+	pci_unregister_driver(&hvfb_pci_stub_driver);
+	vmbus_driver_unregister(&hvfb_drv);
+}
+
+module_init(hvfb_drv_init);
+module_exit(hvfb_drv_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Microsoft Hyper-V Synthetic Video Frame Buffer Driver");