Input: add vmmouse driver

VMMouse enables low-latency mouse-cursor-movements for VMWare and QEMU
guests. By removing the guest cursor and using the host as a guest cursor
the cursor movement appears instant although in reality there is some lag.
To be able to do this, the host's view of the cursor position must exactly
match the guest's view and an absolute pointer device is needed. Enter the
VMMouse. While the VMMouse driver has historically been an Xorg user-space
driver, implementing it as a kernel imput driver enables rootless Xorg and
new compositing display servers for VMware guests.

Signed-off-by: Thomas Hellstrom <[e-mail]>
Signed-off-by: Dmitry Torokhov <[e-mail]>

MAINTAINERS

···
 S:	Maintained
 F:	drivers/misc/vmw_balloon.c
 
+VMWARE VMMOUSE SUBDRIVER
+M:	"VMware Graphics" <[e-mail]>
+M:	"VMware, Inc." <[e-mail]>
+L:	[e-mail]
+S:	Maintained
+F:	drivers/input/mouse/vmmouse.c
+F:	drivers/input/mouse/vmmouse.h
+
 VMWARE VMXNET3 ETHERNET DRIVER
 M:	Shreyas Bhatewara <[e-mail]>
 M:	"VMware, Inc." <[e-mail]>

drivers/input/mouse/Kconfig

···
 
 	  If unsure, say Y.
 
+config MOUSE_PS2_VMMOUSE
+	bool "Virtual mouse (vmmouse)"
+	depends on MOUSE_PS2 && X86 && HYPERVISOR_GUEST
+	help
+	  Say Y here if you are running under control of VMware hypervisor
+	  (ESXi, Workstation or Fusion). Also make sure that when you enable
+	  this option, you remove the xf86-input-vmmouse user-space driver
+	  or upgrade it to at least xf86-input-vmmouse 13.0.1, which doesn't
+	  load in the presence of an in-kernel vmmouse driver.
+
+	  If unsure, say N.
+
 config MOUSE_SERIAL
 	tristate "Serial mouse"
 	select SERIO

drivers/input/mouse/Makefile

···
 psmouse-$(CONFIG_MOUSE_PS2_TRACKPOINT)	+= trackpoint.o
 psmouse-$(CONFIG_MOUSE_PS2_TOUCHKIT)	+= touchkit_ps2.o
 psmouse-$(CONFIG_MOUSE_PS2_CYPRESS)	+= cypress_ps2.o
+psmouse-$(CONFIG_MOUSE_PS2_VMMOUSE)	+= vmmouse.o
 
 elan_i2c-objs := elan_i2c_core.o
 elan_i2c-$(CONFIG_MOUSE_ELAN_I2C_I2C)	+= elan_i2c_i2c.o

drivers/input/mouse/psmouse-base.c

···
 #include "sentelic.h"
 #include "cypress_ps2.h"
 #include "focaltech.h"
+#include "vmmouse.h"
 
 #define DRIVER_DESC	"PS/2 mouse driver"
 
···
 		}
 	}
 
+	if (psmouse_do_detect(vmmouse_detect, psmouse, set_properties) == 0) {
+		if (max_proto > PSMOUSE_IMEX) {
+			if (!set_properties || vmmouse_init(psmouse) == 0)
+				return PSMOUSE_VMMOUSE;
+		}
+	}
+
 /*
  * Try Kensington ThinkingMouse (we try first, because synaptics probe
  * upsets the thinkingmouse).
···
 		.alias		= "focaltech",
 		.detect		= focaltech_detect,
 		.init		= focaltech_init,
+	},
+#endif
+#ifdef CONFIG_MOUSE_PS2_VMMOUSE
+	{
+		.type		= PSMOUSE_VMMOUSE,
+		.name		= VMMOUSE_PSNAME,
+		.alias		= "vmmouse",
+		.detect		= vmmouse_detect,
+		.init		= vmmouse_init,
 	},
 #endif
 	{

drivers/input/mouse/psmouse.h

···
 	PSMOUSE_SYNAPTICS_RELATIVE,
 	PSMOUSE_CYPRESS,
 	PSMOUSE_FOCALTECH,
+	PSMOUSE_VMMOUSE,
 	PSMOUSE_AUTO		/* This one should always be last */
 };
 

drivers/input/mouse/vmmouse.c

···
+/*
+ * Driver for Virtual PS/2 Mouse on VMware and QEMU hypervisors.
+ *
+ * Copyright (C) 2014, VMware, Inc. All Rights Reserved.
+ *
+ * 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.
+ *
+ * Twin device code is hugely inspired by the ALPS driver.
+ * Authors:
+ *   Dmitry Torokhov <[e-mail]>
+ *   Thomas Hellstrom <[e-mail]>
+ */
+
+#include <linux/input.h>
+#include <linux/serio.h>
+#include <linux/libps2.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <asm/hypervisor.h>
+
+#include "psmouse.h"
+#include "vmmouse.h"
+
+#define VMMOUSE_PROTO_MAGIC			0x564D5868U
+#define VMMOUSE_PROTO_PORT			0x5658
+
+/*
+ * Main commands supported by the vmmouse hypervisor port.
+ */
+#define VMMOUSE_PROTO_CMD_GETVERSION		10
+#define VMMOUSE_PROTO_CMD_ABSPOINTER_DATA	39
+#define VMMOUSE_PROTO_CMD_ABSPOINTER_STATUS	40
+#define VMMOUSE_PROTO_CMD_ABSPOINTER_COMMAND	41
+#define VMMOUSE_PROTO_CMD_ABSPOINTER_RESTRICT   86
+
+/*
+ * Subcommands for VMMOUSE_PROTO_CMD_ABSPOINTER_COMMAND
+ */
+#define VMMOUSE_CMD_ENABLE			0x45414552U
+#define VMMOUSE_CMD_DISABLE			0x000000f5U
+#define VMMOUSE_CMD_REQUEST_RELATIVE		0x4c455252U
+#define VMMOUSE_CMD_REQUEST_ABSOLUTE		0x53424152U
+
+#define VMMOUSE_ERROR				0xffff0000U
+
+#define VMMOUSE_VERSION_ID			0x3442554aU
+
+#define VMMOUSE_RELATIVE_PACKET			0x00010000U
+
+#define VMMOUSE_LEFT_BUTTON			0x20
+#define VMMOUSE_RIGHT_BUTTON			0x10
+#define VMMOUSE_MIDDLE_BUTTON			0x08
+
+/*
+ * VMMouse Restrict command
+ */
+#define VMMOUSE_RESTRICT_ANY                    0x00
+#define VMMOUSE_RESTRICT_CPL0                   0x01
+#define VMMOUSE_RESTRICT_IOPL                   0x02
+
+#define VMMOUSE_MAX_X                           0xFFFF
+#define VMMOUSE_MAX_Y                           0xFFFF
+
+#define VMMOUSE_VENDOR "VMware"
+#define VMMOUSE_NAME   "VMMouse"
+
+/**
+ * struct vmmouse_data - private data structure for the vmmouse driver
+ *
+ * @abs_dev: "Absolute" device used to report absolute mouse movement.
+ * @phys: Physical path for the absolute device.
+ * @dev_name: Name attribute name for the absolute device.
+ */
+struct vmmouse_data {
+	struct input_dev *abs_dev;
+	char phys[32];
+	char dev_name[128];
+};
+
+/**
+ * Hypervisor-specific bi-directional communication channel
+ * implementing the vmmouse protocol. Should never execute on
+ * bare metal hardware.
+ */
+#define VMMOUSE_CMD(cmd, in1, out1, out2, out3, out4)	\
+({							\
+	unsigned long __dummy1, __dummy2;		\
+	__asm__ __volatile__ ("inl %%dx" :		\
+		"=a"(out1),				\
+		"=b"(out2),				\
+		"=c"(out3),				\
+		"=d"(out4),				\
+		"=S"(__dummy1),				\
+		"=D"(__dummy2) :			\
+		"a"(VMMOUSE_PROTO_MAGIC),		\
+		"b"(in1),				\
+		"c"(VMMOUSE_PROTO_CMD_##cmd),		\
+		"d"(VMMOUSE_PROTO_PORT) :		\
+		"memory");		                \
+})
+
+/**
+ * vmmouse_report_button - report button state on the correct input device
+ *
+ * @psmouse:  Pointer to the psmouse struct
+ * @abs_dev:  The absolute input device
+ * @rel_dev:  The relative input device
+ * @pref_dev: The preferred device for reporting
+ * @code:     Button code
+ * @value:    Button value
+ *
+ * Report @value and @code on @pref_dev, unless the button is already
+ * pressed on the other device, in which case the state is reported on that
+ * device.
+ */
+static void vmmouse_report_button(struct psmouse *psmouse,
+				  struct input_dev *abs_dev,
+				  struct input_dev *rel_dev,
+				  struct input_dev *pref_dev,
+				  unsigned int code, int value)
+{
+	if (test_bit(code, abs_dev->key))
+		pref_dev = abs_dev;
+	else if (test_bit(code, rel_dev->key))
+		pref_dev = rel_dev;
+
+	input_report_key(pref_dev, code, value);
+}
+
+/**
+ * vmmouse_report_events - process events on the vmmouse communications channel
+ *
+ * @psmouse: Pointer to the psmouse struct
+ *
+ * This function pulls events from the vmmouse communications channel and
+ * reports them on the correct (absolute or relative) input device. When the
+ * communications channel is drained, or if we've processed more than 255
+ * psmouse commands, the function returns PSMOUSE_FULL_PACKET. If there is a
+ * host- or synchronization error, the function returns PSMOUSE_BAD_DATA in
+ * the hope that the caller will reset the communications channel.
+ */
+static psmouse_ret_t vmmouse_report_events(struct psmouse *psmouse)
+{
+	struct input_dev *rel_dev = psmouse->dev;
+	struct vmmouse_data *priv = psmouse->private;
+	struct input_dev *abs_dev = priv->abs_dev;
+	struct input_dev *pref_dev;
+	u32 status, x, y, z;
+	u32 dummy1, dummy2, dummy3;
+	unsigned int queue_length;
+	unsigned int count = 255;
+
+	while (count--) {
+		/* See if we have motion data. */
+		VMMOUSE_CMD(ABSPOINTER_STATUS, 0,
+			    status, dummy1, dummy2, dummy3);
+		if ((status & VMMOUSE_ERROR) == VMMOUSE_ERROR) {
+			psmouse_err(psmouse, "failed to fetch status data\n");
+			/*
+			 * After a few attempts this will result in
+			 * reconnect.
+			 */
+			return PSMOUSE_BAD_DATA;
+		}
+
+		queue_length = status & 0xffff;
+		if (queue_length == 0)
+			break;
+
+		if (queue_length % 4) {
+			psmouse_err(psmouse, "invalid queue length\n");
+			return PSMOUSE_BAD_DATA;
+		}
+
+		/* Now get it */
+		VMMOUSE_CMD(ABSPOINTER_DATA, 4, status, x, y, z);
+
+		/*
+		 * And report what we've got. Prefer to report button
+		 * events on the same device where we report motion events.
+		 * This doesn't work well with the mouse wheel, though. See
+		 * below. Ideally we would want to report that on the
+		 * preferred device as well.
+		 */
+		if (status & VMMOUSE_RELATIVE_PACKET) {
+			pref_dev = rel_dev;
+			input_report_rel(rel_dev, REL_X, (s32)x);
+			input_report_rel(rel_dev, REL_Y, -(s32)y);
+		} else {
+			pref_dev = abs_dev;
+			input_report_abs(abs_dev, ABS_X, x);
+			input_report_abs(abs_dev, ABS_Y, y);
+		}
+
+		/* Xorg seems to ignore wheel events on absolute devices */
+		input_report_rel(rel_dev, REL_WHEEL, -(s8)((u8) z));
+
+		vmmouse_report_button(psmouse, abs_dev, rel_dev,
+				      pref_dev, BTN_LEFT,
+				      status & VMMOUSE_LEFT_BUTTON);
+		vmmouse_report_button(psmouse, abs_dev, rel_dev,
+				      pref_dev, BTN_RIGHT,
+				      status & VMMOUSE_RIGHT_BUTTON);
+		vmmouse_report_button(psmouse, abs_dev, rel_dev,
+				      pref_dev, BTN_MIDDLE,
+				      status & VMMOUSE_MIDDLE_BUTTON);
+		input_sync(abs_dev);
+		input_sync(rel_dev);
+	}
+
+	return PSMOUSE_FULL_PACKET;
+}
+
+/**
+ * vmmouse_process_byte - process data on the ps/2 channel
+ *
+ * @psmouse: Pointer to the psmouse struct
+ *
+ * When the ps/2 channel indicates that there is vmmouse data available,
+ * call vmmouse channel processing. Otherwise, continue to accept bytes. If
+ * there is a synchronization or communication data error, return
+ * PSMOUSE_BAD_DATA in the hope that the caller will reset the mouse.
+ */
+static psmouse_ret_t vmmouse_process_byte(struct psmouse *psmouse)
+{
+	unsigned char *packet = psmouse->packet;
+
+	switch (psmouse->pktcnt) {
+	case 1:
+		return (packet[0] & 0x8) == 0x8 ?
+			PSMOUSE_GOOD_DATA : PSMOUSE_BAD_DATA;
+
+	case 2:
+		return PSMOUSE_GOOD_DATA;
+
+	default:
+		return vmmouse_report_events(psmouse);
+	}
+}
+
+/**
+ * vmmouse_disable - Disable vmmouse
+ *
+ * @psmouse: Pointer to the psmouse struct
+ *
+ * Tries to disable vmmouse mode.
+ */
+static void vmmouse_disable(struct psmouse *psmouse)
+{
+	u32 status;
+	u32 dummy1, dummy2, dummy3, dummy4;
+
+	VMMOUSE_CMD(ABSPOINTER_COMMAND, VMMOUSE_CMD_DISABLE,
+		    dummy1, dummy2, dummy3, dummy4);
+
+	VMMOUSE_CMD(ABSPOINTER_STATUS, 0,
+		    status, dummy1, dummy2, dummy3);
+
+	if ((status & VMMOUSE_ERROR) != VMMOUSE_ERROR)
+		psmouse_warn(psmouse, "failed to disable vmmouse device\n");
+}
+
+/**
+ * vmmouse_enable - Enable vmmouse and request absolute mode.
+ *
+ * @psmouse: Pointer to the psmouse struct
+ *
+ * Tries to enable vmmouse mode. Performs basic checks and requests
+ * absolute vmmouse mode.
+ * Returns 0 on success, -ENODEV on failure.
+ */
+static int vmmouse_enable(struct psmouse *psmouse)
+{
+	u32 status, version;
+	u32 dummy1, dummy2, dummy3, dummy4;
+
+	/*
+	 * Try enabling the device. If successful, we should be able to
+	 * read valid version ID back from it.
+	 */
+	VMMOUSE_CMD(ABSPOINTER_COMMAND, VMMOUSE_CMD_ENABLE,
+		    dummy1, dummy2, dummy3, dummy4);
+
+	/*
+	 * See if version ID can be retrieved.
+	 */
+	VMMOUSE_CMD(ABSPOINTER_STATUS, 0, status, dummy1, dummy2, dummy3);
+	if ((status & 0x0000ffff) == 0) {
+		psmouse_dbg(psmouse, "empty flags - assuming no device\n");
+		return -ENXIO;
+	}
+
+	VMMOUSE_CMD(ABSPOINTER_DATA, 1 /* single item */,
+		    version, dummy1, dummy2, dummy3);
+	if (version != VMMOUSE_VERSION_ID) {
+		psmouse_dbg(psmouse, "Unexpected version value: %u vs %u\n",
+			    (unsigned) version, VMMOUSE_VERSION_ID);
+		vmmouse_disable(psmouse);
+		return -ENXIO;
+	}
+
+	/*
+	 * Restrict ioport access, if possible.
+	 */
+	VMMOUSE_CMD(ABSPOINTER_RESTRICT, VMMOUSE_RESTRICT_CPL0,
+		    dummy1, dummy2, dummy3, dummy4);
+
+	VMMOUSE_CMD(ABSPOINTER_COMMAND, VMMOUSE_CMD_REQUEST_ABSOLUTE,
+		    dummy1, dummy2, dummy3, dummy4);
+
+	return 0;
+}
+
+/*
+ * Array of supported hypervisors.
+ */
+static const struct hypervisor_x86 *vmmouse_supported_hypervisors[] = {
+	&x86_hyper_vmware,
+#ifdef CONFIG_KVM_GUEST
+	&x86_hyper_kvm,
+#endif
+};
+
+/**
+ * vmmouse_check_hypervisor - Check if we're running on a supported hypervisor
+ */
+static bool vmmouse_check_hypervisor(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(vmmouse_supported_hypervisors); i++)
+		if (vmmouse_supported_hypervisors[i] == x86_hyper)
+			return true;
+
+	return false;
+}
+
+/**
+ * vmmouse_detect - Probe whether vmmouse is available
+ *
+ * @psmouse: Pointer to the psmouse struct
+ * @set_properties: Whether to set psmouse name and vendor
+ *
+ * Returns 0 if vmmouse channel is available. Negative error code if not.
+ */
+int vmmouse_detect(struct psmouse *psmouse, bool set_properties)
+{
+	u32 response, version, dummy1, dummy2;
+
+	if (!vmmouse_check_hypervisor()) {
+		psmouse_dbg(psmouse,
+			    "VMMouse not running on supported hypervisor.\n");
+		return -ENXIO;
+	}
+
+	if (!request_region(VMMOUSE_PROTO_PORT, 4, "vmmouse")) {
+		psmouse_dbg(psmouse, "VMMouse port in use.\n");
+		return -EBUSY;
+	}
+
+	/* Check if the device is present */
+	response = ~VMMOUSE_PROTO_MAGIC;
+	VMMOUSE_CMD(GETVERSION, 0, version, response, dummy1, dummy2);
+	if (response != VMMOUSE_PROTO_MAGIC || version == 0xffffffffU) {
+		release_region(VMMOUSE_PROTO_PORT, 4);
+		return -ENXIO;
+	}
+
+	if (set_properties) {
+		psmouse->vendor = VMMOUSE_VENDOR;
+		psmouse->name = VMMOUSE_NAME;
+		psmouse->model = version;
+	}
+
+	release_region(VMMOUSE_PROTO_PORT, 4);
+
+	return 0;
+}
+
+/**
+ * vmmouse_disconnect - Take down vmmouse driver
+ *
+ * @psmouse: Pointer to the psmouse struct
+ *
+ * Takes down vmmouse driver and frees resources set up in vmmouse_init().
+ */
+static void vmmouse_disconnect(struct psmouse *psmouse)
+{
+	struct vmmouse_data *priv = psmouse->private;
+
+	vmmouse_disable(psmouse);
+	psmouse_reset(psmouse);
+	input_unregister_device(priv->abs_dev);
+	kfree(priv);
+	release_region(VMMOUSE_PROTO_PORT, 4);
+}
+
+/**
+ * vmmouse_reconnect - Reset the ps/2 - and vmmouse connections
+ *
+ * @psmouse: Pointer to the psmouse struct
+ *
+ * Attempts to reset the mouse connections. Returns 0 on success and
+ * -1 on failure.
+ */
+static int vmmouse_reconnect(struct psmouse *psmouse)
+{
+	int error;
+
+	psmouse_reset(psmouse);
+	vmmouse_disable(psmouse);
+	error = vmmouse_enable(psmouse);
+	if (error) {
+		psmouse_err(psmouse,
+			    "Unable to re-enable mouse when reconnecting, err: %d\n",
+			    error);
+		return error;
+	}
+
+	return 0;
+}
+
+/**
+ * vmmouse_init - Initialize the vmmouse driver
+ *
+ * @psmouse: Pointer to the psmouse struct
+ *
+ * Requests the device and tries to enable vmmouse mode.
+ * If successful, sets up the input device for relative movement events.
+ * It also allocates another input device and sets it up for absolute motion
+ * events. Returns 0 on success and -1 on failure.
+ */
+int vmmouse_init(struct psmouse *psmouse)
+{
+	struct vmmouse_data *priv;
+	struct input_dev *rel_dev = psmouse->dev, *abs_dev;
+	int error;
+
+	if (!request_region(VMMOUSE_PROTO_PORT, 4, "vmmouse")) {
+		psmouse_dbg(psmouse, "VMMouse port in use.\n");
+		return -EBUSY;
+	}
+
+	psmouse_reset(psmouse);
+	error = vmmouse_enable(psmouse);
+	if (error)
+		goto release_region;
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	abs_dev = input_allocate_device();
+	if (!priv || !abs_dev) {
+		error = -ENOMEM;
+		goto init_fail;
+	}
+
+	priv->abs_dev = abs_dev;
+	psmouse->private = priv;
+
+	input_set_capability(rel_dev, EV_REL, REL_WHEEL);
+
+	/* Set up and register absolute device */
+	snprintf(priv->phys, sizeof(priv->phys), "%s/input1",
+		 psmouse->ps2dev.serio->phys);
+
+	/* Mimic name setup for relative device in psmouse-base.c */
+	snprintf(priv->dev_name, sizeof(priv->dev_name), "%s %s %s",
+		 VMMOUSE_PSNAME, VMMOUSE_VENDOR, VMMOUSE_NAME);
+	abs_dev->phys = priv->phys;
+	abs_dev->name = priv->dev_name;
+	abs_dev->id.bustype = BUS_I8042;
+	abs_dev->id.vendor = 0x0002;
+	abs_dev->id.product = PSMOUSE_VMMOUSE;
+	abs_dev->id.version = psmouse->model;
+	abs_dev->dev.parent = &psmouse->ps2dev.serio->dev;
+
+	error = input_register_device(priv->abs_dev);
+	if (error)
+		goto init_fail;
+
+	/* Set absolute device capabilities */
+	input_set_capability(abs_dev, EV_KEY, BTN_LEFT);
+	input_set_capability(abs_dev, EV_KEY, BTN_RIGHT);
+	input_set_capability(abs_dev, EV_KEY, BTN_MIDDLE);
+	input_set_capability(abs_dev, EV_ABS, ABS_X);
+	input_set_capability(abs_dev, EV_ABS, ABS_Y);
+	input_set_abs_params(abs_dev, ABS_X, 0, VMMOUSE_MAX_X, 0, 0);
+	input_set_abs_params(abs_dev, ABS_Y, 0, VMMOUSE_MAX_Y, 0, 0);
+
+	psmouse->protocol_handler = vmmouse_process_byte;
+	psmouse->disconnect = vmmouse_disconnect;
+	psmouse->reconnect = vmmouse_reconnect;
+
+	return 0;
+
+init_fail:
+	vmmouse_disable(psmouse);
+	psmouse_reset(psmouse);
+	input_free_device(abs_dev);
+	kfree(priv);
+	psmouse->private = NULL;
+
+release_region:
+	release_region(VMMOUSE_PROTO_PORT, 4);
+
+	return error;
+}

drivers/input/mouse/vmmouse.h

···
+/*
+ * Driver for Virtual PS/2 Mouse on VMware and QEMU hypervisors.
+ *
+ * Copyright (C) 2014, VMware, Inc. All Rights Reserved.
+ *
+ * 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.
+ */
+
+#ifndef _VMMOUSE_H
+#define _VMMOUSE_H
+
+#ifdef CONFIG_MOUSE_PS2_VMMOUSE
+#define VMMOUSE_PSNAME  "VirtualPS/2"
+
+int vmmouse_detect(struct psmouse *psmouse, bool set_properties);
+int vmmouse_init(struct psmouse *psmouse);
+#else
+static inline int vmmouse_detect(struct psmouse *psmouse, bool set_properties)
+{
+	return -ENOSYS;
+}
+static inline int vmmouse_init(struct psmouse *psmouse)
+{
+	return -ENOSYS;
+}
+#endif
+
+#endif