[RFC] video: Add Hyper-V Synthetic Video Frame Buffer Driver
diff mbox series

Message ID 1360955396-14183-1-git-send-email-haiyangz@microsoft.com
State New, archived
Headers show
Series
  • [RFC] video: Add Hyper-V Synthetic Video Frame Buffer Driver
Related show

Commit Message

Haiyang Zhang Feb. 15, 2013, 7:09 p.m. UTC
This is the driver for the Hyper-V Synthetic Video, which supports screen
resolution up to Full HD 1920x1080 on Windows Server 2012 host, and 1600x1200
on  Windows Server 2008 R2 or earlier.
It also solves the double mouse cursor issue of the emulated video mode.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/video/Kconfig     |   11 +
 drivers/video/Makefile    |    1 +
 drivers/video/hyperv_fb.c |  983 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/video/vesafb.c    |   48 +++
 include/linux/hyperv.h    |   11 +
 5 files changed, 1054 insertions(+), 0 deletions(-)
 create mode 100644 drivers/video/hyperv_fb.c

Comments

Olaf Hering Feb. 17, 2013, 2:32 p.m. UTC | #1
On Fri, Feb 15, Haiyang Zhang wrote:

> +config HYPERV_FB

This should probably be FB_HYPERB to follow the naming of all other
drivers.

Olaf
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Haiyang Zhang Feb. 17, 2013, 7:10 p.m. UTC | #2
> From: Olaf Hering
> Sent: Sunday, February 17, 2013 9:32 AM
> To: Haiyang Zhang
> Cc: FlorianSchandinat@gmx.de; linux-fbdev@vger.kernel.org; KY Srinivasan; jasowang@redhat.com; linux-kernel@vger.kernel.org; devel@linuxdriverproject.org
> Subject: Re: [PATCH RFC] video: Add Hyper-V Synthetic Video Frame Buffer Driver

> On Fri, Feb 15, Haiyang Zhang wrote:

> +config HYPERV_FB

> This should probably be FB_HYPERB to follow the naming of all other
> drivers.

Will do.

Thanks,
- Haiyang
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Geert Uytterhoeven Feb. 18, 2013, 10:29 a.m. UTC | #3
On Fri, Feb 15, 2013 at 8:09 PM, Haiyang Zhang <haiyangz@microsoft.com> wrote:
> +/* Allocate framebuffer memory */
> +#define FOUR_MEGA (4*1024*1024)
> +#define NALLOC 10
> +static void *hvfb_getmem(void)
> +{
> +       ulong *p;
> +       int i, j;
> +       ulong ret = 0;
> +
> +       if (screen_fb_size == FOUR_MEGA) {
> +               ret = __get_free_pages(GFP_KERNEL|__GFP_ZERO,
> +                                      get_order(FOUR_MEGA));
> +               goto out1;
> +       }
> +
> +       if (screen_fb_size != FOUR_MEGA * 2)
> +               return NULL;
> +
> +       /*
> +        * Windows 2012 requires frame buffer size to be 8MB, which exceeds
> +        * the limit of __get_free_pages(). So, we allocate multiple 4MB
> +        * chunks, and find out two adjacent ones.
> +        */
> +       p = kmalloc(NALLOC * sizeof(ulong), GFP_KERNEL);
> +       if (!p)
> +               return NULL;
> +
> +       for (i = 0; i < NALLOC; i++)
> +               p[i] = __get_free_pages(GFP_KERNEL|__GFP_ZERO,
> +                                       get_order(FOUR_MEGA));
> +
> +       for (i = 0; i < NALLOC; i++)
> +               for (j = 0; j < NALLOC; j++) {
> +                       if (p[j] && p[i] && virt_to_phys((void *)p[j]) -
> +                           virt_to_phys((void *)p[i]) == FOUR_MEGA &&
> +                           p[j] - p[i] == FOUR_MEGA) {
> +                               ret = p[i];
> +                               goto out;
> +                       }
> +               }
> +
> +out:
> +       for (i = 0; i < NALLOC; i++)
> +               if (p[i] && !(ret && (p[i] == ret || p[i] == ret + FOUR_MEGA)))
> +                       free_pages(p[i], get_order(FOUR_MEGA));
> +
> +       kfree(p);
> +
> +out1:
> +       if (!ret)
> +               return NULL;
> +
> +       /* Get an extra ref-count to prevent page error when x-window exits */
> +       for (i = 0; i < screen_fb_size; i += PAGE_SIZE)
> +               atomic_inc(&virt_to_page((void *)ret + i)->_count);
> +
> +       return (void *)ret;
> +}

Please instead reserve some memory at boot time, or allocate it very early
(cfr. ps3fb).

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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Olaf Hering Feb. 19, 2013, 4:51 p.m. UTC | #4
On Fri, Feb 15, Haiyang Zhang wrote:

> @@ -508,6 +544,18 @@ static int __init vesafb_init(void)
>  	int ret;
>  	char *option = NULL;
>  
> +#if IS_ENABLED(CONFIG_HYPERV_FB)
> +	/*
> +	 * On Hyper-V both the emulated and synthetic video devices are
> +	 * available. To avoid conflicts, we disable vesafb for the emulated
> +	 * video if hyperv_fb is configured.
> +	 */
> +	if (is_hyperv()) {
> +		pr_info("Disabled vesafb on Hyper-V.\n");
> +		return -ENODEV;
> +	}
> +#endif

What is the reason for this hook? Is it not possible to claim the
display like its appearently done by other drivers (like radeonfb can
take over display from vesafb)?

Olaf
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Olaf Hering Feb. 19, 2013, 6:40 p.m. UTC | #5
On Tue, Feb 19, Haiyang Zhang wrote:

> The emulated video device is a separate device from the synthetic video.
> The synthetic driver can only take control of the synthetic video, but not
> the emulated video.

Please add this to the comment above.

> Actually, we already have a similar mechanism in ata/ata_piix.c to disable
> emulated IDE drive on Hyper-V, so it won't conflict with the synthetic drive.

I havent read the vesafb code, but I think it can kind of give up the
hardware, something ata_piix can not do.

Olaf
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Olaf Hering Feb. 21, 2013, 3:53 p.m. UTC | #6
On Tue, Feb 19, Haiyang Zhang wrote:

> > I havent read the vesafb code, but I think it can kind of give up the
> > hardware, something ata_piix can not do.
> 
> In my test, the vesafb doesn't automatically give up the emulated video device,
> unless I add the DMI based mechanism to let it exit on Hyper-V.

>From reading the code, it seems to do that via
do_remove_conflicting_framebuffers(). hypervfb does not set apertures
etc, so that function is a noop.


My point is that with this new driver distro kernel will have no console
output until hypervfb is loaded. On native hardware there is at least
vesafb which can display something until initrd is running. So if the
hypervisor allows that hypervfb can shutdown the emulated vesa hardware
then it should do that.


Olaf
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Haiyang Zhang Feb. 22, 2013, 4:11 a.m. UTC | #7
> From: Olaf Hering
> Sent: Thursday, February 21, 2013 10:53 AM
> To: Haiyang Zhang
> Cc: FlorianSchandinat@gmx.de; linux-fbdev@vger.kernel.org; KY Srinivasan; jasowang@redhat.com; linux-kernel@vger.kernel.org; devel@linuxdriverproject.org
> Subject: Re: [PATCH RFC] video: Add Hyper-V Synthetic Video Frame Buffer Driver
> 
> On Tue, Feb 19, Haiyang Zhang wrote:
> 
> > In my test, the vesafb doesn't automatically give up the emulated video device,
> > unless I add the DMI based mechanism to let it exit on Hyper-V.
> 
> From reading the code, it seems to do that via
> do_remove_conflicting_framebuffers(). hypervfb does not set apertures
> etc, so that function is a noop.

We are currently allocating a new framebuffer for hyperv_fb, which is different
from the framebuffer for the emulated video. So this cannot be detected by
do_remove_conflicting_framebuffers() based on apertures_overlap().

> My point is that with this new driver distro kernel will have no console
> output until hypervfb is loaded. On native hardware there is at least
> vesafb which can display something until initrd is running. So if the
> hypervisor allows that hypervfb can shutdown the emulated vesa hardware
> then it should do that.

Since the generic vga driver starts to work early in the boot process, the console
messages are still displayed without vesafb. Actually, I didn't see any console 
messages missing when comparing it to the original VM before my patch.

Thanks,
- Haiyang
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Olaf Hering Feb. 28, 2013, 3:16 p.m. UTC | #8
On Fri, Feb 15, Haiyang Zhang wrote:

> +	if (fb_get_options("hyperv_fb", &opt) || !opt || !*opt)

> +	strcpy(info->fix.id, "hyperv");


Here is a mismatch between video=<optname> and /proc/fb output.
Both should have the same string IMO.

Olaf
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Patch
diff mbox series

diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index 1e2f2d8..7d2a721 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -2449,6 +2449,17 @@  config FB_PUV3_UNIGFX
 	  Choose this option if you want to use the Unigfx device as a
 	  framebuffer device. Without the support of PCI & AGP.
 
+config HYPERV_FB
+	tristate "Microsoft Hyper-V Synthetic Video support"
+	depends on FB && HYPERV
+	select FB_SYS_FILLRECT
+	select FB_SYS_COPYAREA
+	select FB_SYS_IMAGEBLIT
+	select FB_SYS_FOPS
+	select FB_DEFERRED_IO
+	help
+	  This framebuffer driver supports Microsoft Hyper-V Synthetic Video.
+
 source "drivers/video/omap/Kconfig"
 source "drivers/video/omap2/Kconfig"
 source "drivers/video/exynos/Kconfig"
diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index 136af7d..dd1c6da 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -148,6 +148,7 @@  obj-$(CONFIG_FB_MSM)              += msm/
 obj-$(CONFIG_FB_NUC900)           += nuc900fb.o
 obj-$(CONFIG_FB_JZ4740)		  += jz4740_fb.o
 obj-$(CONFIG_FB_PUV3_UNIGFX)      += fb-puv3.o
+obj-$(CONFIG_HYPERV_FB)		  += hyperv_fb.o
 
 # Platform or fallback drivers go here
 obj-$(CONFIG_FB_UVESA)            += uvesafb.o
diff --git a/drivers/video/hyperv_fb.c b/drivers/video/hyperv_fb.c
new file mode 100644
index 0000000..d7c660f
--- /dev/null
+++ b/drivers/video/hyperv_fb.c
@@ -0,0 +1,983 @@ 
+/*
+ * Copyright (c) 2012, Microsoft Corporation.
+ *
+ * Author:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ */
+
+/*
+ * 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
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/completion.h>
+#include <linux/fb.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_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)
+
+
+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_MAX			= 11
+};
+
+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_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;
+	};
+} __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 / 30)
+
+struct hvfb_par {
+	struct fb_info *info;
+	bool info_ready; /* info and its fields are set up */
+	struct completion wait;
+	u32 synthvid_version;
+
+	struct delayed_work dwork;
+	spinlock_t area_lock; /* protect changed area */
+	int x1, y1, x2, y2; /* changed rectangle area */
+
+	u32 pseudo_palette[16];
+	u8 init_buf[MAX_VMBUS_PKT_SIZE];
+	u8 recv_buf[MAX_VMBUS_PKT_SIZE];
+};
+
+static uint screen_width = HVFB_WIDTH;
+static uint screen_height = HVFB_HEIGHT;
+static uint screen_depth;
+static uint screen_fb_size;
+
+/* 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 hvfb_par *par;
+	struct synthvid_msg msg;
+
+	if (!info)
+		return -ENODEV;
+
+	par = info->par;
+	if (!par->info_ready)
+		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));
+
+	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;
+	msg.dirt.rect[0].y1 = y1;
+	msg.dirt.rect[0].x2 = x2;
+	msg.dirt.rect[0].y2 = y2;
+
+	synthvid_send(hdev, &msg);
+
+	return 0;
+}
+
+
+/*
+ * 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_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) {
+		synthvid_send_situ(hdev);
+		synthvid_send_ptr(hdev);
+	}
+
+}
+
+/* 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 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 t, ret = 0;
+
+	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;
+
+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 */
+	if (vmbus_proto_version == VERSION_WS2008 ||
+	    vmbus_proto_version == VERSION_WIN7)
+		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN7);
+	else
+		ret = synthvid_negotiate_ver(hdev, SYNTHVID_VERSION_WIN8);
+
+	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;
+		screen_fb_size = SYNTHVID_FB_SIZE_WIN7;
+	} else {
+		screen_depth = SYNTHVID_DEPTH_WIN8;
+		screen_fb_size = SYNTHVID_FB_SIZE_WIN8;
+	}
+
+	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 t, ret = 0;
+
+	/* 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 =
+		virt_to_phys(info->screen_base);
+	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 error;
+	}
+	if (msg->vram_ack.user_ctx != virt_to_phys(info->screen_base)) {
+		pr_err("Unable to set VRAM location\n");
+		ret = -ENODEV;
+		goto error;
+	}
+
+	/* Send situation and pointer update */
+	synthvid_send_situ(hdev);
+	synthvid_send_ptr(hdev);
+
+	return 0;
+
+error:
+	return ret;
+}
+
+
+static inline void hvfb_init_rect(struct hvfb_par *par)
+{
+	par->x1 = par->y1 = INT_MAX;
+	par->x2 = par->y2 = 0;
+}
+
+/*
+ * Delayed work callback:
+ * It is called at HVFB_UPDATE_DELAY or longer time interval to process
+ * screen updates from non-deferred I/O, such as imageblit, which can happen
+ * at high frequency.
+ */
+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;
+	int x1, y1, x2, y2;
+	ulong flags;
+
+	spin_lock_irqsave(&par->area_lock, flags);
+
+	x1 = par->x1;
+	y1 = par->y1;
+	x2 = par->x2;
+	y2 = par->y2;
+
+	hvfb_init_rect(par);
+
+	spin_unlock_irqrestore(&par->area_lock, flags);
+
+	if (x1 == INT_MAX)
+		return;
+
+	synthvid_update(info, x1, y1, x2, y2);
+}
+
+/*
+ * Record the updated screen area, and schedule the delayed work.
+ * If the work is still on the queue, schedule_delayed_work() will
+ * automatically ignore the new request. But the updated area is
+ * always recorded, and will be handled by the queued work.
+ */
+static void hvfb_add_rect(struct fb_info *info, int x1, int y1,
+			  int x2, int y2)
+{
+	struct hvfb_par *par = info->par;
+	ulong flags;
+
+	spin_lock_irqsave(&par->area_lock, flags);
+
+	if (x1 < par->x1)
+		par->x1 = x1;
+	if (y1 < par->y1)
+		par->y1 = y1;
+
+	if (x2 > par->x2)
+		par->x2 = x2;
+	if (y2 > par->y2)
+		par->y2 = y2;
+
+	spin_unlock_irqrestore(&par->area_lock, flags);
+
+	schedule_delayed_work(&par->dwork, HVFB_UPDATE_DELAY);
+}
+
+
+
+/* Framebuffer operation handlers */
+
+static ssize_t hvfb_write(struct fb_info *info, const char __user *buf,
+			  size_t count, loff_t *ppos)
+{
+	ssize_t ret;
+
+	ret = fb_sys_write(info, buf, count, ppos);
+
+	hvfb_add_rect(info, 0, 0,
+		      info->var.xres, info->var.yres);
+
+	return ret;
+}
+
+
+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);
+
+	return 0;
+}
+
+static void hvfb_fillrect(struct fb_info *info, const struct fb_fillrect *rect)
+{
+	sys_fillrect(info, rect);
+
+	hvfb_add_rect(info, rect->dx, rect->dy,
+		      rect->dx + rect->width, rect->dy + rect->height);
+}
+
+static void hvfb_copyarea(struct fb_info *info, const struct fb_copyarea *area)
+{
+	sys_copyarea(info, area);
+
+	hvfb_add_rect(info, area->dx, area->dy,
+		      area->dx + area->width, area->dy + area->height);
+}
+
+static void hvfb_imageblit(struct fb_info *info, const struct fb_image *image)
+{
+	sys_imageblit(info, image);
+
+	hvfb_add_rect(info, image->dx, image->dy,
+		      image->dx + image->width, image->dy + image->height);
+}
+
+static struct fb_ops hvfb_ops = {
+	.owner = THIS_MODULE,
+	.fb_read = fb_sys_read,
+	.fb_write = hvfb_write,
+	.fb_check_var = hvfb_check_var,
+	.fb_set_par = hvfb_set_par,
+	.fb_setcolreg = hvfb_setcolreg,
+	.fb_fillrect = hvfb_fillrect,
+	.fb_copyarea = hvfb_copyarea,
+	.fb_imageblit = hvfb_imageblit,
+};
+
+
+/*
+ * Callback for the deferred I/O.
+ * Applications, such as X-Window, use deferred I/O mechanism to put screen
+ * updates in batches, and send to fb driver periodically.
+ */
+static void hvfb_deferred_io(struct fb_info *info, struct list_head *pl)
+{
+	struct page *page;
+	ulong pa, pb, min = ULONG_MAX, max = 0;
+	int ymin, ymax;
+
+	list_for_each_entry(page, pl, lru) {
+		pa = page->index << PAGE_SHIFT;
+		pb = pa + PAGE_SIZE - 1;
+		if (pa < min)
+			min = pa;
+		if (pb > max)
+			max = pb;
+	}
+
+	if (max == 0)
+		return;
+
+	ymin = min / info->fix.line_length;
+	ymax = max / info->fix.line_length + 1;
+	if (ymax > info->var.yres)
+		ymax = info->var.yres;
+
+	synthvid_update(info, 0, ymin, info->var.xres, ymax);
+}
+
+static struct fb_deferred_io hvfb_defio = {
+	.delay = HVFB_UPDATE_DELAY,
+	.deferred_io = hvfb_deferred_io,
+};
+
+
+/* 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("hyperv_fb", &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 ||
+	    (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 framebuffer memory */
+#define FOUR_MEGA (4*1024*1024)
+#define NALLOC 10
+static void *hvfb_getmem(void)
+{
+	ulong *p;
+	int i, j;
+	ulong ret = 0;
+
+	if (screen_fb_size == FOUR_MEGA) {
+		ret = __get_free_pages(GFP_KERNEL|__GFP_ZERO,
+				       get_order(FOUR_MEGA));
+		goto out1;
+	}
+
+	if (screen_fb_size != FOUR_MEGA * 2)
+		return NULL;
+
+	/*
+	 * Windows 2012 requires frame buffer size to be 8MB, which exceeds
+	 * the limit of __get_free_pages(). So, we allocate multiple 4MB
+	 * chunks, and find out two adjacent ones.
+	 */
+	p = kmalloc(NALLOC * sizeof(ulong), GFP_KERNEL);
+	if (!p)
+		return NULL;
+
+	for (i = 0; i < NALLOC; i++)
+		p[i] = __get_free_pages(GFP_KERNEL|__GFP_ZERO,
+					get_order(FOUR_MEGA));
+
+	for (i = 0; i < NALLOC; i++)
+		for (j = 0; j < NALLOC; j++) {
+			if (p[j] && p[i] && virt_to_phys((void *)p[j]) -
+			    virt_to_phys((void *)p[i]) == FOUR_MEGA &&
+			    p[j] - p[i] == FOUR_MEGA) {
+				ret = p[i];
+				goto out;
+			}
+		}
+
+out:
+	for (i = 0; i < NALLOC; i++)
+		if (p[i] && !(ret && (p[i] == ret || p[i] == ret + FOUR_MEGA)))
+			free_pages(p[i], get_order(FOUR_MEGA));
+
+	kfree(p);
+
+out1:
+	if (!ret)
+		return NULL;
+
+	/* Get an extra ref-count to prevent page error when x-window exits */
+	for (i = 0; i < screen_fb_size; i += PAGE_SIZE)
+		atomic_inc(&virt_to_page((void *)ret + i)->_count);
+
+	return (void *)ret;
+}
+
+/* Free the frame buffer */
+static void hvfb_putmem(void *p)
+{
+	int i;
+
+	if (!p)
+		return;
+
+	for (i = 0; i < screen_fb_size; i += PAGE_SIZE)
+		atomic_dec(&virt_to_page(p + i)->_count);
+
+	free_pages((ulong)p, get_order(FOUR_MEGA));
+
+	if (screen_fb_size == FOUR_MEGA * 2)
+		free_pages((ulong)p + FOUR_MEGA, get_order(FOUR_MEGA));
+}
+
+
+static int hvfb_probe(struct hv_device *hdev,
+		      const struct hv_vmbus_device_id *dev_id)
+{
+	struct fb_info *info;
+	void *fb = NULL;
+	struct hvfb_par *par;
+	int ret = 0;
+
+	info = framebuffer_alloc(sizeof(struct hvfb_par), &hdev->device);
+	if (!info) {
+		pr_err("No memory for framebuffer info\n");
+		return -ENOMEM;
+	}
+
+	par = info->par;
+	par->info = info;
+	par->info_ready = false;
+	init_completion(&par->wait);
+
+	/* 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;
+	}
+
+	fb = hvfb_getmem();
+	if (!fb) {
+		pr_err("No memory for framebuffer\n");
+		ret = -ENOMEM;
+		goto error2;
+	}
+
+	hvfb_get_option(info);
+	pr_info("Screen resolution: %dx%d, Color depth: %d\n",
+		screen_width, screen_height, screen_depth);
+
+
+	/* Set up fb_info */
+	info->flags = FBINFO_DEFAULT | FBINFO_VIRTFB;
+
+	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};
+
+	} 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.activate = FB_ACTIVATE_NOW;
+	info->var.height = -1;
+	info->var.width = -1;
+	info->var.vmode = FB_VMODE_NONINTERLACED;
+
+	strcpy(info->fix.id, "hyperv");
+	info->fix.smem_start = virt_to_phys(fb);
+	info->fix.smem_len = screen_width * screen_height * screen_depth / 8;
+	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->screen_base = fb;
+	info->pseudo_palette = par->pseudo_palette;
+
+	par->info_ready = true;
+
+	/* Send config to host */
+	ret = synthvid_send_config(hdev);
+	if (ret)
+		goto error2;
+
+	info->fbdefio = &hvfb_defio;
+	fb_deferred_io_init(info);
+
+	INIT_DELAYED_WORK(&par->dwork, hvfb_update_work);
+	spin_lock_init(&par->area_lock);
+	hvfb_init_rect(par);
+	ret = register_framebuffer(info);
+	if (ret) {
+		pr_err("Unable to register framebuffer\n");
+		goto error;
+	}
+
+	return 0;
+
+error:
+	cancel_delayed_work_sync(&par->dwork);
+	fb_deferred_io_cleanup(info);
+error2:
+	vmbus_close(hdev->channel);
+error1:
+	hv_set_drvdata(hdev, NULL);
+	framebuffer_release(info);
+	hvfb_putmem(fb);
+	return ret;
+}
+
+
+static int hvfb_remove(struct hv_device *hdev)
+{
+	struct fb_info *info = hv_get_drvdata(hdev);
+	void *fb = info->screen_base;
+	struct hvfb_par *par = info->par;
+
+	fb_deferred_io_cleanup(info);
+	unregister_framebuffer(info);
+	cancel_delayed_work_sync(&par->dwork);
+
+	vmbus_close(hdev->channel);
+	hv_set_drvdata(hdev, NULL);
+
+	framebuffer_release(info);
+	hvfb_putmem(fb);
+
+	return 0;
+}
+
+
+static const struct hv_vmbus_device_id id_table[] = {
+	/* Synthetic Video Device GUID */
+	{HV_SYNTHVID_GUID},
+	{}
+};
+
+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,
+};
+
+
+static int __init hvfb_drv_init(void)
+{
+	return vmbus_driver_register(&hvfb_drv);
+}
+
+static void __exit hvfb_drv_exit(void)
+{
+	vmbus_driver_unregister(&hvfb_drv);
+}
+
+module_init(hvfb_drv_init);
+module_exit(hvfb_drv_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_VERSION(HV_DRV_VERSION);
+MODULE_DESCRIPTION("Microsoft Hyper-V Synthetic Video Frame Buffer Driver");
diff --git a/drivers/video/vesafb.c b/drivers/video/vesafb.c
index 501b340..34b82075 100644
--- a/drivers/video/vesafb.c
+++ b/drivers/video/vesafb.c
@@ -19,6 +19,7 @@ 
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/screen_info.h>
+#include <linux/dmi.h>
 
 #include <video/vga.h>
 #include <asm/io.h>
@@ -495,6 +496,41 @@  err:
 	return err;
 }
 
+
+#if IS_ENABLED(CONFIG_HYPERV_FB)
+static struct dmi_system_id __initdata hyperv_dmi[] = {
+	{
+		.ident = "Microsoft Virtual PC",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Microsoft Corporation"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Virtual Machine"),
+			DMI_MATCH(DMI_PRODUCT_VERSION, "VS2005R2"),
+		},
+	},
+
+	{
+		.ident = "Microsoft Hyper-V",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Microsoft Corporation"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Virtual Machine"),
+		},
+	},
+
+	{}
+};
+
+/* Check if we are running on Microsoft Hyper-V platform */
+static bool __init is_hyperv(void)
+{
+	/*
+	 * If the first match is "Microsoft Hyper-V", it means we are not
+	 * running on the MS Virtual PC or other platforms, but on Hyper-V.
+	 */
+	return dmi_first_match(hyperv_dmi) == hyperv_dmi + 1;
+}
+#endif
+
+
 static struct platform_driver vesafb_driver = {
 	.driver	= {
 		.name	= "vesafb",
@@ -508,6 +544,18 @@  static int __init vesafb_init(void)
 	int ret;
 	char *option = NULL;
 
+#if IS_ENABLED(CONFIG_HYPERV_FB)
+	/*
+	 * On Hyper-V both the emulated and synthetic video devices are
+	 * available. To avoid conflicts, we disable vesafb for the emulated
+	 * video if hyperv_fb is configured.
+	 */
+	if (is_hyperv()) {
+		pr_info("Disabled vesafb on Hyper-V.\n");
+		return -ENODEV;
+	}
+#endif
+
 	/* ignore error return of fb_get_options */
 	fb_get_options("vesafb", &option);
 	vesafb_setup(option);
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index df77ba9..a460ee4 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1253,6 +1253,17 @@  void vmbus_driver_unregister(struct hv_driver *hv_driver);
 		}
 
 /*
+ * Synthetic Video GUID
+ * {DA0A7802-E377-4aac-8E77-0558EB1073F8}
+ */
+#define HV_SYNTHVID_GUID \
+	.guid = { \
+			0x02, 0x78, 0x0a, 0xda, 0x77, 0xe3, 0xac, 0x4a, \
+			0x8e, 0x77, 0x05, 0x58, 0xeb, 0x10, 0x73, 0xf8 \
+		}
+
+
+/*
  * Common header for Hyper-V ICs
  */