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[PATCH 7/7] drivers/misc: introduce Freescale hypervisor management driver



The Freescale hypervisor management driver provides several services to
drivers and applications related to the Freescale hypervisor:

1. An ioctl interface for querying and managing partitions

2. A file interface to reading incoming doorbells

3. An interrupt handler for shutting down the partition upon receiving the
   shutdown doorbell from a manager partition

4. An interface for receiving callbacks when a managed partition shuts down.

Signed-off-by: Timur Tabi <timur@xxxxxxxxxxxxx>
---
 drivers/misc/Kconfig           |    7 +
 drivers/misc/Makefile          |    1 +
 drivers/misc/fsl_hypervisor.c  |  941 ++++++++++++++++++++++++++++++++++++++++
 include/linux/fsl_hypervisor.h |  203 +++++++++
 4 files changed, 1152 insertions(+), 0 deletions(-)
 create mode 100644 drivers/misc/fsl_hypervisor.c
 create mode 100644 include/linux/fsl_hypervisor.h

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 4e007c6..4aa6032 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -216,6 +216,13 @@ config ENCLOSURE_SERVICES
 	  driver (SCSI/ATA) which supports enclosures
 	  or a SCSI enclosure device (SES) to use these services.
 
+config FSL_HV_MANAGER
+	tristate "Freescale hypervisor management driver"
+	depends on FSL_SOC
+	help
+	  This driver allows applications to communicate with the Freescale
+	  Hypervisor.
+
 config SGI_XP
 	tristate "Support communication between SGI SSIs"
 	depends on NET
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index f546860..2c23e34 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_SENSORS_BH1770)	+= bh1770glc.o
 obj-$(CONFIG_SENSORS_APDS990X)	+= apds990x.o
 obj-$(CONFIG_SGI_IOC4)		+= ioc4.o
 obj-$(CONFIG_ENCLOSURE_SERVICES) += enclosure.o
+obj-$(CONFIG_FSL_HV_MANAGER)	+= fsl_hypervisor.o
 obj-$(CONFIG_KGDB_TESTS)	+= kgdbts.o
 obj-$(CONFIG_SGI_XP)		+= sgi-xp/
 obj-$(CONFIG_SGI_GRU)		+= sgi-gru/
diff --git a/drivers/misc/fsl_hypervisor.c b/drivers/misc/fsl_hypervisor.c
new file mode 100644
index 0000000..a03aa7b
--- /dev/null
+++ b/drivers/misc/fsl_hypervisor.c
@@ -0,0 +1,941 @@
+/** @file
+ * Freescale Hypervisor Management Driver
+ *
+ * This driver contains functions to support the Freescale hypervisor.
+ */
+/* Copyright (C) 2008-2010 Freescale Semiconductor, Inc.
+ * Author: Timur Tabi <timur@xxxxxxxxxxxxx>
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2.  This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/err.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/poll.h>
+#include <linux/of.h>
+#include <linux/reboot.h>
+#include <linux/uaccess.h>
+#include <linux/notifier.h>
+
+#include <linux/io.h>
+#include <asm/fsl_hcalls.h>
+
+#include <linux/fsl_hypervisor.h>
+
+static BLOCKING_NOTIFIER_HEAD(failover_subscribers);
+
+/**
+ * ioctl_restart: ioctl interface for FSL_HV_IOCTL_PARTITION_RESTART
+ *
+ * Restart a running partition
+ */
+static long ioctl_restart(struct fsl_hv_ioctl_restart __user *p)
+{
+	struct fsl_hv_ioctl_restart param;
+
+	/* Get the parameters from the user */
+	if (copy_from_user(&param, p, sizeof(struct fsl_hv_ioctl_restart)))
+		return -EFAULT;
+
+	param.ret = fh_partition_restart(param.partition);
+
+	if (copy_to_user(&p->ret, &param.ret, sizeof(__u32)))
+		return -EFAULT;
+
+	return 0;
+}
+
+/**
+ * ioctl_status: ioctl interface for FSL_HV_IOCTL_PARTITION_STATUS
+ *
+ * Query the status of a partition
+ */
+static long ioctl_status(struct fsl_hv_ioctl_status __user *p)
+{
+	struct fsl_hv_ioctl_status param;
+	u32 status;
+
+	/* Get the parameters from the user */
+	if (copy_from_user(&param, p, sizeof(struct fsl_hv_ioctl_status)))
+		return -EFAULT;
+
+	param.ret = fh_partition_get_status(param.partition, &status);
+	if (!param.ret)
+		param.status = status;
+
+	if (copy_to_user(p, &param, sizeof(struct fsl_hv_ioctl_status)))
+		return -EFAULT;
+
+	return 0;
+}
+
+/**
+ * ioctl_start: ioctl interface for FSL_HV_IOCTL_PARTITION_START
+ *
+ * Start a stopped partition.
+ */
+static long ioctl_start(struct fsl_hv_ioctl_start __user *p)
+{
+	struct fsl_hv_ioctl_start param;
+
+	/* Get the parameters from the user */
+	if (copy_from_user(&param, p, sizeof(struct fsl_hv_ioctl_start)))
+		return -EFAULT;
+
+	param.ret = fh_partition_start(param.partition, param.entry_point,
+				       param.load);
+
+	if (copy_to_user(&p->ret, &param.ret, sizeof(__u32)))
+		return -EFAULT;
+
+	return 0;
+}
+
+/**
+ * ioctl_stop: ioctl interface for FSL_HV_IOCTL_PARTITION_STOP
+ *
+ * Stop a running partition
+ */
+static long ioctl_stop(struct fsl_hv_ioctl_stop __user *p)
+{
+	struct fsl_hv_ioctl_stop param;
+
+	/* Get the parameters from the user */
+	if (copy_from_user(&param, p, sizeof(struct fsl_hv_ioctl_stop)))
+		return -EFAULT;
+
+	param.ret = fh_partition_stop(param.partition);
+
+	if (copy_to_user(&p->ret, &param.ret, sizeof(__u32)))
+		return -EFAULT;
+
+	return 0;
+}
+
+/**
+ * ioctl_memcpy: ioctl interface for FSL_HV_IOCTL_MEMCPY
+ *
+ * The FH_MEMCPY hypercall takes an array of address/address/size structures
+ * to represent the data being copied.  As a convenience to the user, this
+ * ioctl takes a user-create buffer and a pointer to a guest physically
+ * contiguous buffer in the remote partition, and creates the
+ * address/address/size array for the hypercall.
+ */
+static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
+{
+	struct fsl_hv_ioctl_memcpy param;
+
+	struct page **pages = NULL;
+	void *sg_list_unaligned = NULL;
+	struct fh_sg_list *sg_list = NULL;
+
+	unsigned int nr_pages;
+	unsigned long lb_offset; /* Offset within a page of the local buffer */
+
+	unsigned int i;
+	long ret = 0;
+	phys_addr_t remote_paddr; /* The next address in the remote buffer */
+	uint32_t count; /* The number of bytes left to copy */
+
+	/* Get the parameters from the user */
+	if (copy_from_user(&param, p, sizeof(struct fsl_hv_ioctl_memcpy)))
+		return -EFAULT;
+
+	/* One partition must be local, the other must be remote.  In other
+	   words, if source and target are both -1, or are both not -1, then
+	   return an error. */
+	if ((param.source == -1) == (param.target == -1))
+		return -EINVAL;
+
+	/*
+	 * The array of pages returned by get_user_pages() covers only
+	 * page-aligned memory.  Since the user buffer is probably not
+	 * page-aligned, we need to handle the discrepancy.
+	 *
+	 * We calculate the offset within a page of the S/G list, and make
+	 * adjustments accordingly.  This will result in a page list that looks
+	 * like this:
+	 *
+	 *      ----    <-- first page starts before the buffer
+	 *     |    |
+	 *     |////|-> ----
+	 *     |////|  |    |
+	 *      ----   |    |
+	 *             |    |
+	 *      ----   |    |
+	 *     |////|  |    |
+	 *     |////|  |    |
+	 *     |////|  |    |
+	 *      ----   |    |
+	 *             |    |
+	 *      ----   |    |
+	 *     |////|  |    |
+	 *     |////|  |    |
+	 *     |////|  |    |
+	 *      ----   |    |
+	 *             |    |
+	 *      ----   |    |
+	 *     |////|  |    |
+	 *     |////|-> ----
+	 *     |    |   <-- last page ends after the buffer
+	 *      ----
+	 *
+	 * The distance between the start of the first page and the start of the
+	 * buffer is lb_offset.  The hashed (///) areas are the parts of the
+	 * page list that contain the actual buffer.
+	 *
+	 * The advantage of this approach is that the number of pages is
+	 * equal to the number of entries in the S/G list that we give to the
+	 * hypervisor.
+	 */
+	lb_offset = param.local_vaddr & (PAGE_SIZE - 1);
+	nr_pages = (param.count + lb_offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
+
+	/* Allocate the buffers we need */
+
+	/* pages is an array of struct page pointers that's initialized by
+	   get_user_pages() */
+	pages = kzalloc(nr_pages * sizeof(struct page *), GFP_KERNEL);
+	if (!pages) {
+		pr_debug("fsl-hv: could not allocate page list\n");
+		return -ENOMEM;
+	}
+
+	/* sg_list is the list of fh_sg_list objects that we pass to the
+	   hypervisor */
+	sg_list_unaligned = kmalloc(nr_pages * sizeof(struct fh_sg_list) +
+		sizeof(struct fh_sg_list) - 1, GFP_KERNEL);
+	if (!sg_list_unaligned) {
+		pr_debug("fsl-hv: could not allocate S/G list\n");
+		return -ENOMEM;
+	}
+	sg_list = PTR_ALIGN(sg_list_unaligned, sizeof(struct fh_sg_list));
+
+	/* Get the physical addresses of the source buffer */
+	down_read(&current->mm->mmap_sem);
+	ret = get_user_pages(current, current->mm,
+		param.local_vaddr - lb_offset, nr_pages,
+		(param.source == -1) ? READ : WRITE,
+		0, pages, NULL);
+	up_read(&current->mm->mmap_sem);
+
+	if (ret != nr_pages) {
+		/* get_user_pages() failed */
+		pr_debug("fsl-hv: could not lock source buffer\n");
+		ret = -EACCES;
+		goto exit;
+	}
+
+	/* reset ret here */
+	ret = 0;
+
+	/* Build the fh_sg_list[] array.  The first page is special
+	   because it's misaligned.*/
+	if (param.source == -1) {
+		sg_list[0].source = page_to_phys(pages[0]) + lb_offset;
+		sg_list[0].target = param.remote_paddr;
+	} else {
+		sg_list[0].source = param.remote_paddr;
+		sg_list[0].target = page_to_phys(pages[0]) + lb_offset;
+	}
+	sg_list[0].size = min_t(uint64_t, param.count, PAGE_SIZE - lb_offset);
+
+	remote_paddr = param.remote_paddr + sg_list[0].size;
+	count = param.count - sg_list[0].size;
+
+	for (i = 1; i < nr_pages; i++) {
+		if (param.source == -1) {
+			/* local to remote */
+			sg_list[i].source = page_to_phys(pages[i]);
+			sg_list[i].target = remote_paddr;
+		} else {
+			/* remote to local */
+			sg_list[i].source = remote_paddr;
+			sg_list[i].target = page_to_phys(pages[i]);
+		}
+		sg_list[i].size = min_t(uint64_t, count, PAGE_SIZE);
+
+		remote_paddr += sg_list[i].size;
+		count -= sg_list[i].size;
+	}
+
+	param.ret = fh_partition_memcpy(param.source, param.target,
+		virt_to_phys(sg_list), nr_pages);
+
+exit:
+	if (pages) {
+		for (i = 0; i < nr_pages; i++)
+			if (pages[i])
+				page_cache_release(pages[i]);
+	}
+
+	kfree(sg_list_unaligned);
+	kfree(pages);
+
+	if (!ret)
+		if (copy_to_user(&p->ret, &param.ret, sizeof(__u32)))
+			return -EFAULT;
+
+	return ret;
+}
+
+/**
+ * ioctl_doorbell: ioctl interface for FSL_HV_IOCTL_DOORBELL
+ *
+ * Ring a doorbell
+ */
+static long ioctl_doorbell(struct fsl_hv_ioctl_doorbell __user *p)
+{
+	struct fsl_hv_ioctl_doorbell param;
+
+	/* Get the parameters from the user */
+	if (copy_from_user(&param, p, sizeof(struct fsl_hv_ioctl_doorbell)))
+		return -EFAULT;
+
+	param.ret = ev_doorbell_send(param.doorbell);
+
+	if (copy_to_user(&p->ret, &param.ret, sizeof(__u32)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static char *strdup_from_user(const char __user *ustr, size_t max)
+{
+	size_t len;
+	char *str;
+
+	len = strnlen_user(ustr, max);
+	if (len > max)
+		return ERR_PTR(-ENAMETOOLONG);
+
+	str = kmalloc(len, GFP_KERNEL);
+	if (!str)
+		return ERR_PTR(-ENOMEM);
+
+	if (copy_from_user(str, ustr, len))
+		return ERR_PTR(-EFAULT);
+
+	return str;
+}
+
+static long ioctl_dtprop(struct fsl_hv_ioctl_prop __user *p, int set)
+{
+	struct fsl_hv_ioctl_prop param;
+	char __user *upath, *upropname;
+	void __user *upropval;
+	char *path = NULL, *propname = NULL;
+	void *propval = NULL;
+	int ret = 0;
+
+	/* Get the parameters from the user */
+	if (copy_from_user(&param, p, sizeof(struct fsl_hv_ioctl_prop)))
+		return -EFAULT;
+
+	upath = (char __user *)(uintptr_t)param.path;
+	upropname = (char __user *)(uintptr_t)param.propname;
+	upropval = (void __user *)(uintptr_t)param.propval;
+
+	path = strdup_from_user(upath, FH_DTPROP_MAX_PATHLEN);
+	if (IS_ERR(path)) {
+		ret = PTR_ERR(path);
+		goto out;
+	}
+
+	propname = strdup_from_user(upropname, FH_DTPROP_MAX_PATHLEN);
+	if (IS_ERR(propname)) {
+		ret = PTR_ERR(propname);
+		goto out;
+	}
+
+	if (param.proplen > FH_DTPROP_MAX_PROPLEN) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	propval = kmalloc(param.proplen, GFP_KERNEL);
+	if (!propval) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	if (set) {
+		if (copy_from_user(propval, upropval, param.proplen)) {
+			ret = -EFAULT;
+			goto out;
+		}
+
+		param.ret = fh_partition_set_dtprop(param.handle,
+						    virt_to_phys(path),
+						    virt_to_phys(propname),
+						    virt_to_phys(propval),
+						    param.proplen);
+	} else {
+		param.ret = fh_partition_get_dtprop(param.handle,
+						    virt_to_phys(path),
+						    virt_to_phys(propname),
+						    virt_to_phys(propval),
+						    &param.proplen);
+
+		if (param.ret == 0) {
+			if (copy_to_user(upropval, propval, param.proplen) ||
+			    put_user(param.proplen, &p->proplen)) {
+				ret = -EFAULT;
+				goto out;
+			}
+		}
+	}
+
+	if (put_user(param.ret, &p->ret))
+		ret = -EFAULT;
+
+out:
+	kfree(path);
+	kfree(propval);
+	kfree(propname);
+
+	return ret;
+}
+
+/**
+ * fsl_hv_ioctl: ioctl main entry point
+ */
+static long fsl_hv_ioctl(struct file *file, unsigned int cmd,
+			 unsigned long argaddr)
+{
+	union fsl_hv_ioctl_param __user *arg =
+		(union fsl_hv_ioctl_param __user *)argaddr;
+	long ret;
+
+	/* Make sure the application is called the right driver. */
+	if (_IOC_TYPE(cmd) != 0) {
+		pr_debug("fsl-hv: ioctl type %u should be 0\n", _IOC_TYPE(cmd));
+		return -EINVAL;
+	}
+
+	/* Make sure the application set the direction flag correctly. */
+	if (_IOC_DIR(cmd) != (_IOC_READ | _IOC_WRITE)) {
+		pr_debug("fsl-hv: ioctl direction should be _IOWR\n");
+		return -EINVAL;
+	}
+
+	/* Make sure the application is passing the right structure to us. */
+	if (_IOC_SIZE(cmd) < sizeof(union fsl_hv_ioctl_param)) {
+		pr_debug("fsl-hv: ioctl size %u is too small (should be %u)\n",
+			 _IOC_SIZE(cmd), sizeof(union fsl_hv_ioctl_param));
+		return -EINVAL;
+	}
+
+	switch (_IOC_NR(cmd)) {
+	case FSL_HV_IOCTL_PARTITION_RESTART:
+		ret = ioctl_restart(&arg->restart);
+		break;
+	case FSL_HV_IOCTL_PARTITION_GET_STATUS:
+		ret = ioctl_status(&arg->status);
+		break;
+	case FSL_HV_IOCTL_PARTITION_START:
+		ret = ioctl_start(&arg->start);
+		break;
+	case FSL_HV_IOCTL_PARTITION_STOP:
+		ret = ioctl_stop(&arg->stop);
+		break;
+	case FSL_HV_IOCTL_MEMCPY:
+		ret = ioctl_memcpy(&arg->memcpy);
+		break;
+	case FSL_HV_IOCTL_DOORBELL:
+		ret = ioctl_doorbell(&arg->doorbell);
+		break;
+	case FSL_HV_IOCTL_GETPROP:
+		ret = ioctl_dtprop(&arg->prop, 0);
+		break;
+	case FSL_HV_IOCTL_SETPROP:
+		ret = ioctl_dtprop(&arg->prop, 1);
+		break;
+	default:
+		pr_debug("fsl-hv: unknown ioctl %u\n", cmd);
+		ret = -ENOIOCTLCMD;
+		break;
+	}
+
+	return ret;
+}
+
+/* Linked list of processes that have us open */
+struct list_head db_list;
+
+/* spinlock for db_list */
+static DEFINE_SPINLOCK(db_list_lock);
+
+/* The size of the doorbell event queue.  This must be a power of two. */
+#define QSIZE	16
+
+/* Returns the next head/tail pointer, wrapping around the queue if necessary */
+#define nextp(x) (((x) + 1) & (QSIZE - 1))
+
+/* Per-open data structure */
+struct doorbell_queue {
+	struct list_head list;
+	spinlock_t lock;
+	wait_queue_head_t wait;
+	unsigned int head;
+	unsigned int tail;
+	uint32_t q[QSIZE];
+};
+
+/* Linked list of ISRs that we registered */
+struct list_head isr_list;
+
+/* Per-ISR data structure */
+struct doorbell_isr {
+	struct list_head list;
+	unsigned int irq;
+	uint32_t doorbell;	/* The doorbell handle */
+	uint32_t partition;	/* The partition handle, if used */
+	struct work_struct work;
+};
+
+/**
+ * fsl_hv_isr - interrupt handler for all doorbells
+ * @param irq - the IRQ (a.k.a. receive handle)
+ *
+ * We use the same interrupt handler for all doorbells.  Whenever a doorbell
+ * is rung, and we receive an interrupt, we just put the handle for that
+ * doorbell (passed to us as *data) into all of the queues.
+ *
+ */
+static irqreturn_t fsl_hv_isr(int irq, void *data)
+{
+	struct doorbell_queue *dbq;
+	unsigned long flags;
+
+	/* Prevent another core from modifying db_list */
+	spin_lock_irqsave(&db_list_lock, flags);
+
+	list_for_each_entry(dbq, &db_list, list) {
+		if (dbq->head != nextp(dbq->tail)) {
+			dbq->q[dbq->tail] = (uint32_t) (uintptr_t) data;
+			/* This memory barrier eliminates the need to grab
+			 * the spinlock for dbq.
+			 */
+			smp_wmb();
+			dbq->tail = nextp(dbq->tail);
+			wake_up_interruptible(&dbq->wait);
+		}
+	}
+
+	spin_unlock_irqrestore(&db_list_lock, flags);
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * fsl_hv_state_change_work_func -- state change worker function
+ *
+ * The state change notification arrives in an interrupt, but we can't call
+ * blocking_notifier_call_chain() in an interrupt handler.  We could call
+ * atomic_notifier_call_chain(), but that would require the clients' call-back
+ * function to run in interrupt context.  Since we don't want to impose that
+ * restriction on the clients, we create a work queue to process the
+ * notification in kernel context.
+ */
+static void fsl_hv_state_change_work_func(struct work_struct *work)
+{
+	struct doorbell_isr *dbisr =
+		container_of(work, struct doorbell_isr, work);
+
+	blocking_notifier_call_chain(&failover_subscribers, dbisr->partition,
+				     NULL);
+}
+
+/**
+ * fsl_hv_state_change_isr - interrupt handler for state-change doorbells
+ */
+static irqreturn_t fsl_hv_state_change_isr(int irq, void *data)
+{
+	unsigned int status;
+	struct doorbell_isr *dbisr = data;
+	int ret;
+
+	/* Determine the new state, and if it's stopped, notify the clients. */
+	ret = fh_partition_get_status(dbisr->partition, &status);
+	if (!ret && (status == FH_PARTITION_STOPPED))
+		schedule_work(&dbisr->work);
+
+	/* Call the normal handler */
+	return fsl_hv_isr(irq, (void *) (uintptr_t) dbisr->doorbell);
+}
+
+/**
+ * fsl_hv_poll - returns a bitmask indicating whether a read will block
+ *
+ * @return unsigned int
+ */
+static unsigned int fsl_hv_poll(struct file *filp, struct poll_table_struct *p)
+{
+	struct doorbell_queue *dbq = filp->private_data;
+	unsigned long flags;
+	unsigned int mask;
+
+	spin_lock_irqsave(&dbq->lock, flags);
+
+	poll_wait(filp, &dbq->wait, p);
+	mask = (dbq->head == dbq->tail) ? 0 : (POLLIN | POLLRDNORM);
+
+	spin_unlock_irqrestore(&dbq->lock, flags);
+
+	return mask;
+}
+
+/**
+ * fsl_hv_read - return the handles for any incoming doorbells
+ *
+ * If there are doorbell handles in the queue for this open instance, then
+ * return them to the caller as an array of 32-bit integers.  Otherwise,
+ * block until there is at least one handle to return.
+ */
+static ssize_t fsl_hv_read(struct file *filp, char __user *buf, size_t len,
+			   loff_t *off)
+{
+	struct doorbell_queue *dbq = filp->private_data;
+	uint32_t __user *p = (uint32_t __user *) buf; /* for put_user() */
+	unsigned long flags;
+	ssize_t count = 0;
+
+	/* Make sure we stop when the user buffer is full. */
+	while (len >= sizeof(uint32_t)) {
+		uint32_t dbell;	/* Local copy of doorbell queue data */
+
+		spin_lock_irqsave(&dbq->lock, flags);
+
+		/* If the queue is empty, then either we're done or we need
+		 * to block.  If the application specified O_NONBLOCK, then
+		 * we return the appropriate error code.
+		 */
+		if (dbq->head == dbq->tail) {
+			spin_unlock_irqrestore(&dbq->lock, flags);
+			if (count)
+				break;
+			if (filp->f_flags & O_NONBLOCK)
+				return -EAGAIN;
+			if (wait_event_interruptible(dbq->wait,
+						     dbq->head != dbq->tail))
+				return -ERESTARTSYS;
+			continue;
+		}
+
+		/* Even though we have an smp_wmb() in the ISR, the core
+		 * might speculatively execute the "dbell = ..." below while
+		 * it's evaluating the if-statement above.  In that case, the
+		 * value put into dbell could be stale if the core accepts the
+		 * speculation. To prevent that, we need a read memory barrier
+		 * here as well.
+		 */
+		smp_rmb();
+
+		/* Copy the data to a temporary local buffer, because
+		 * we can't call copy_to_user() from inside a spinlock
+		 */
+		dbell = dbq->q[dbq->head];
+		dbq->head = nextp(dbq->head);
+
+		spin_unlock_irqrestore(&dbq->lock, flags);
+
+		if (put_user(dbell, p))
+			return -EFAULT;
+		p++;
+		count += sizeof(uint32_t);
+		len -= sizeof(uint32_t);
+	}
+
+	return count;
+}
+
+/**
+ * fsl_hv_open - open the driver
+ *
+ * Open the driver and prepare for reading doorbells.
+ *
+ * Every time an application opens the driver, we create a doorbell queue
+ * for that file handle.  This queue is used for any incoming doorbells.
+ */
+static int fsl_hv_open(struct inode *inode, struct file *filp)
+{
+	struct doorbell_queue *dbq;
+	unsigned long flags;
+	int ret = 0;
+
+	dbq = kzalloc(sizeof(struct doorbell_queue), GFP_KERNEL);
+	if (!dbq) {
+		pr_err("fsl-hv: out of memory\n");
+		return -ENOMEM;
+	}
+
+	spin_lock_init(&dbq->lock);
+	init_waitqueue_head(&dbq->wait);
+
+	spin_lock_irqsave(&db_list_lock, flags);
+	list_add(&dbq->list, &db_list);
+	spin_unlock_irqrestore(&db_list_lock, flags);
+
+	filp->private_data = dbq;
+
+	return ret;
+}
+
+/**
+ * fsl_hv_close - close the driver
+ */
+static int fsl_hv_close(struct inode *inode, struct file *filp)
+{
+	struct doorbell_queue *dbq = filp->private_data;
+	unsigned long flags;
+
+	int ret = 0;
+
+	spin_lock_irqsave(&db_list_lock, flags);
+	list_del(&dbq->list);
+	spin_unlock_irqrestore(&db_list_lock, flags);
+
+	kfree(dbq);
+
+	return ret;
+}
+
+static const struct file_operations fsl_hv_fops = {
+	.owner = THIS_MODULE,
+	.open = fsl_hv_open,
+	.release = fsl_hv_close,
+	.poll = fsl_hv_poll,
+	.read = fsl_hv_read,
+	.unlocked_ioctl = fsl_hv_ioctl,
+};
+
+static struct miscdevice fsl_hv_misc_dev = {
+	MISC_DYNAMIC_MINOR,
+	"fsl-hv",
+	&fsl_hv_fops
+};
+
+static DECLARE_WORK(power_off, (work_func_t) kernel_power_off);
+
+static irqreturn_t fsl_hv_shutdown_isr(int irq, void *data)
+{
+	schedule_work(&power_off);
+
+	/* We should never get here */
+	return IRQ_NONE;
+}
+
+/**
+ * get_parent_handle -- returns the handle of the parent of the given node
+ *
+ * The handle is the value of the 'reg' property
+ */
+static int get_parent_handle(struct device_node *np)
+{
+	struct device_node *parent;
+	const uint32_t *prop;
+	int len;
+
+	parent = of_get_parent(np);
+	if (!parent)
+		/* It's not really possible for this to fail */
+		return -ENODEV;
+
+	prop = of_get_property(parent, "reg", &len);
+	of_node_put(parent);
+
+	if (!prop || (len != sizeof(uint32_t)))
+		/* This can happen only if the node is malformed */
+		return -ENODEV;
+
+	return *prop;
+}
+
+/**
+ * fsl_hv_failover_register -- register a callback for failover events
+ *
+ * This function is called by device drivers to register their callback
+ * functions for fail-over events.
+ */
+int fsl_hv_failover_register(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&failover_subscribers, nb);
+}
+EXPORT_SYMBOL(fsl_hv_failover_register);
+
+/**
+ * fsl_hv_failover_unregister -- unregister a callback for failover events
+ */
+int fsl_hv_failover_unregister(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&failover_subscribers, nb);
+}
+EXPORT_SYMBOL(fsl_hv_failover_unregister);
+
+/**
+ * has_fsl_hypervisor - return TRUE if we're running under FSL hypervisor
+ *
+ * This function checks to see if we're running under the Freescale
+ * hypervisor, and returns zero if we're not, or non-zero if we are.
+ *
+ * First, it checks if MSR[GS]==1, which means we're running under some
+ * hypervisor.  Then it checks if there is a hypervisor node in the device
+ * tree.  Currently, that means there needs to be a node in the root called
+ * "hypervisor" and which has a property named "fsl,hv-version".
+ */
+static int has_fsl_hypervisor(void)
+{
+	struct device_node *node;
+	int ret;
+
+	if (!(mfmsr() & MSR_GS))
+		return 0;
+
+	node = of_find_node_by_path("/hypervisor");
+	if (!node)
+		return 0;
+
+	ret = of_find_property(node, "fsl,hv-version", NULL) != NULL;
+
+	of_node_put(node);
+
+	return ret;
+}
+
+/**
+ * fsl_hypervisor_init: Freescale hypervisor management driver init
+ *
+ * This function is called when this module is loaded.
+ *
+ * Register ourselves as a miscellaneous driver.  This will register the
+ * fops structure and create the right sysfs entries for udev.
+ */
+static int __init fsl_hypervisor_init(void)
+{
+	struct device_node *np;
+	struct doorbell_isr *dbisr, *n;
+	int ret;
+
+	pr_info("Freescale hypervisor management driver\n");
+
+	if (!has_fsl_hypervisor()) {
+		pr_info("fsl-hv: no hypervisor found\n");
+		return -ENODEV;
+	}
+
+	ret = misc_register(&fsl_hv_misc_dev);
+	if (ret) {
+		pr_err("fsl-hv: cannot register device\n");
+		return ret;
+	}
+
+	INIT_LIST_HEAD(&db_list);
+	INIT_LIST_HEAD(&isr_list);
+
+	for_each_compatible_node(np, NULL, "epapr,hv-receive-doorbell") {
+		unsigned int irq;
+		const uint32_t *handle;
+
+		handle = of_get_property(np, "interrupts", NULL);
+		irq = irq_of_parse_and_map(np, 0);
+		if (!handle || (irq == NO_IRQ)) {
+			pr_err("fsl-hv: no 'interrupts' property in %s node\n",
+				np->full_name);
+			continue;
+		}
+
+		dbisr = kzalloc(sizeof(*dbisr), GFP_KERNEL);
+		if (!dbisr)
+			goto out_of_memory;
+
+		dbisr->irq = irq;
+		dbisr->doorbell = *handle;
+		INIT_WORK(&dbisr->work, fsl_hv_state_change_work_func);
+
+		if (of_device_is_compatible(np, "fsl,hv-shutdown-doorbell")) {
+			/* The shutdown doorbell gets its own ISR */
+			ret = request_irq(irq, fsl_hv_shutdown_isr, 0,
+					  np->name, dbisr);
+		} else if (of_device_is_compatible(np,
+			"fsl,hv-state-change-doorbell")) {
+			/* The state change doorbell triggers a notification if
+			 * the state of the managed partition changes to
+			 * "stopped". We need a separate interrupt handler for
+			 * that, and we also need to know the handle of the
+			 * target partition, not just the handle of the
+			 * doorbell.
+			 */
+			dbisr->partition = ret = get_parent_handle(np);
+			if (ret < 0) {
+				pr_err("fsl-hv: node %s has missing or "
+				       "malformed parent\n", np->full_name);
+				kfree(dbisr);
+				continue;
+			}
+			ret = request_irq(irq, fsl_hv_state_change_isr, 0,
+					  np->name, dbisr);
+		} else
+			ret = request_irq(irq, fsl_hv_isr, 0, np->name, dbisr);
+
+		if (ret < 0) {
+			pr_err("fsl-hv: could not request irq %u for node %s\n",
+			       irq, np->full_name);
+			kfree(dbisr);
+			continue;
+		}
+
+		list_add(&dbisr->list, &isr_list);
+
+		pr_info("fsl-hv: registered handler for doorbell %u\n",
+			*handle);
+	}
+
+	return 0;
+
+out_of_memory:
+	list_for_each_entry_safe(dbisr, n, &isr_list, list) {
+		free_irq(dbisr->irq, dbisr);
+		list_del(&dbisr->list);
+		kfree(dbisr);
+	}
+
+	misc_deregister(&fsl_hv_misc_dev);
+
+	return -ENOMEM;
+}
+
+/**
+ * fsl_hypervisor_exit: Freescale hypervisor management driver termination
+ *
+ * This function is called when this driver is unloaded.
+ */
+static void __exit fsl_hypervisor_exit(void)
+{
+	struct doorbell_isr *dbisr, *n;
+
+	list_for_each_entry_safe(dbisr, n, &isr_list, list) {
+		free_irq(dbisr->irq, dbisr);
+		list_del(&dbisr->list);
+		kfree(dbisr);
+	}
+
+	misc_deregister(&fsl_hv_misc_dev);
+}
+
+module_init(fsl_hypervisor_init);
+module_exit(fsl_hypervisor_exit);
+
+MODULE_AUTHOR("Timur Tabi <timur@xxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Freescale hypervisor management driver");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/fsl_hypervisor.h b/include/linux/fsl_hypervisor.h
new file mode 100644
index 0000000..63740a2
--- /dev/null
+++ b/include/linux/fsl_hypervisor.h
@@ -0,0 +1,203 @@
+/*
+ * Freescale hypervisor ioctl interface
+ *
+ * Copyright (C) 2008-2011 Freescale Semiconductor, Inc.
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2.  This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ *
+ * This file is used by the Freescale hypervisor management driver.  It can
+ * also be included by applications that need to communicate with the driver
+ * via the ioctl interface.
+ */
+
+#ifndef FSL_HYPERVISOR_H
+#define FSL_HYPERVISOR_H
+
+#include <linux/types.h>
+
+/**
+ * Freescale hypervisor ioctl parameter
+ */
+union fsl_hv_ioctl_param {
+
+	/**
+	 * @ret: Return value.
+	 *
+	 * This is always the first word of any structure.
+	 */
+	__u32 ret;
+
+	/**
+	 * struct fsl_hv_ioctl_restart: restart a partition
+	 * @ret: return error code from the hypervisor
+	 * @partition: the ID of the partition to restart, or -1 for the
+	 *             calling partition
+	 *
+	 * Used by FSL_HV_IOCTL_PARTITION_RESTART
+	 */
+	struct fsl_hv_ioctl_restart {
+		__u32 ret;
+		__u32 partition;
+	} restart;
+
+	/**
+	 * struct fsl_hv_ioctl_status: get a partition's status
+	 * @ret: return error code from the hypervisor
+	 * @partition: the ID of the partition to query, or -1 for the
+	 *             calling partition
+	 * @status: The returned status of the partition
+	 *
+	 * Used by FSL_HV_IOCTL_PARTITION_GET_STATUS
+	 *
+	 * Values of 'status':
+	 *    0 = Stopped
+	 *    1 = Running
+	 *    2 = Starting
+	 *    3 = Stopping
+	 */
+	struct fsl_hv_ioctl_status {
+		__u32 ret;
+		__u32 partition;
+		__u32 status;
+	} status;
+
+	/**
+	 * struct fsl_hv_ioctl_start: start a partition
+	 * @ret: return error code from the hypervisor
+	 * @partition: the ID of the partition to control
+	 * @entry_point: The offset within the guest IMA to start execution
+	 * @load: If non-zero, reload the partition's images before starting
+	 *
+	 * Used by FSL_HV_IOCTL_PARTITION_START
+	 */
+	struct fsl_hv_ioctl_start {
+		__u32 ret;
+		__u32 partition;
+		__u32 entry_point;
+		__u32 load;
+	} start;
+
+	/**
+	 * struct fsl_hv_ioctl_stop: stop a partition
+	 * @ret: return error code from the hypervisor
+	 * @partition: the ID of the partition to stop, or -1 for the calling
+	 *             partition
+	 *
+	 * Used by FSL_HV_IOCTL_PARTITION_STOP
+	 */
+	struct fsl_hv_ioctl_stop {
+		__u32 ret;
+		__u32 partition;
+	} stop;
+
+	/**
+	 * struct fsl_hv_ioctl_memcpy: copy memory between partitions
+	 * @ret: return error code from the hypervisor
+	 * @source: the partition ID of the source partition, or -1 for this
+	 *          partition
+	 * @target: the partition ID of the target partition, or -1 for this
+	 *          partition
+	 * @local_addr: user-space virtual address of a buffer in the local
+	 *              partition
+	 * @remote_addr: guest physical address of a buffer in the
+	 *           remote partition
+	 * @count: the number of bytes to copy.  Both the local and remote
+	 *         buffers must be at least 'count' bytes long
+	 *
+	 * Used by FSL_HV_IOCTL_MEMCPY
+	 *
+	 * The 'local' partition is the partition that calls this ioctl.  The
+	 * 'remote' partition is a different partition.  The data is copied from
+	 * the 'source' paritition' to the 'target' partition.
+	 *
+	 * The buffer in the remote partition must be guest physically
+	 * contiguous.
+	 *
+	 * This ioctl does not support copying memory between two remote
+	 * partitions or within the same partition, so either 'source' or
+	 * 'target' (but not both) must be -1.  In other words, either
+	 *
+	 *      source == local and target == remote
+	 * or
+	 *      source == remote and target == local
+	 */
+	struct fsl_hv_ioctl_memcpy {
+		__u32 ret;
+		__u32 source;
+		__u32 target;
+		__u64 local_vaddr;
+		__u64 remote_paddr;
+		__u64 count;
+	} memcpy;
+
+	/**
+	 * struct fsl_hv_ioctl_doorbell: ring a doorbell
+	 * @ret: return error code from the hypervisor
+	 * @doorbell: the handle of the doorbell to ring doorbell
+	 *
+	 * Used by FSL_HV_IOCTL_DOORBELL
+	 */
+	struct fsl_hv_ioctl_doorbell {
+		__u32 ret;
+		__u32 doorbell;
+	} doorbell;
+
+	/**
+	 * struct fsl_hv_ioctl_prop: get/set a device tree property
+	 * @ret: return error code from the hypervisor
+	 * @handle: handle of partition whose tree to access
+	 * @path: virtual address of path name of node to access
+	 * @propname: virtual address of name of property to access
+	 * @propval: virtual address of property data buffer
+	 * @proplen: Size of property data buffer
+	 *
+	 * Used by FSL_HV_IOCTL_DOORBELL
+	 */
+	struct fsl_hv_ioctl_prop {
+		__u32 ret;
+		__u32 handle;
+		__u64 path;
+		__u64 propname;
+		__u64 propval;
+		__u32 proplen;
+	} prop;
+};
+
+/*
+ * ioctl commands.
+ */
+enum {
+	FSL_HV_IOCTL_PARTITION_RESTART = 1, /* Boot another partition */
+	FSL_HV_IOCTL_PARTITION_GET_STATUS = 2, /* Boot another partition */
+	FSL_HV_IOCTL_PARTITION_START = 3, /* Boot another partition */
+	FSL_HV_IOCTL_PARTITION_STOP = 4, /* Stop this or another partition */
+	FSL_HV_IOCTL_MEMCPY = 5, /* Copy data from one partition to another */
+	FSL_HV_IOCTL_DOORBELL = 6, /* Ring a doorbell */
+
+	/* Get a property from another guest's device tree */
+	FSL_HV_IOCTL_GETPROP = 7,
+
+	/* Set a property in another guest's device tree */
+	FSL_HV_IOCTL_SETPROP = 8,
+};
+
+#ifdef __KERNEL__
+
+/**
+ * fsl_hv_event_register -- register a callback for failover events
+ *
+ * This function is called by device drivers to register their callback
+ * functions for fail-over events.
+ */
+int fsl_hv_failover_register(struct notifier_block *nb);
+
+/**
+ * fsl_hv_event_unregister -- unregister a callback for failover events
+ */
+int fsl_hv_failover_unregister(struct notifier_block *nb);
+
+#endif
+
+#endif
-- 
1.7.3.4


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