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path: root/drivers/lguest/lguest_user.c
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Diffstat (limited to 'drivers/lguest/lguest_user.c')
-rw-r--r--drivers/lguest/lguest_user.c127
1 files changed, 92 insertions, 35 deletions
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index b8ee103eed5f..32e297121058 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -7,32 +7,83 @@
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <linux/sched.h>
+#include <linux/eventfd.h>
+#include <linux/file.h>
#include "lg.h"
-/*L:055 When something happens, the Waker process needs a way to stop the
- * kernel running the Guest and return to the Launcher. So the Waker writes
- * LHREQ_BREAK and the value "1" to /dev/lguest to do this. Once the Launcher
- * has done whatever needs attention, it writes LHREQ_BREAK and "0" to release
- * the Waker. */
-static int break_guest_out(struct lg_cpu *cpu, const unsigned long __user*input)
+bool send_notify_to_eventfd(struct lg_cpu *cpu)
{
- unsigned long on;
+ unsigned int i;
+ struct lg_eventfd_map *map;
+
+ /* lg->eventfds is RCU-protected */
+ rcu_read_lock();
+ map = rcu_dereference(cpu->lg->eventfds);
+ for (i = 0; i < map->num; i++) {
+ if (map->map[i].addr == cpu->pending_notify) {
+ eventfd_signal(map->map[i].event, 1);
+ cpu->pending_notify = 0;
+ break;
+ }
+ }
+ rcu_read_unlock();
+ return cpu->pending_notify == 0;
+}
- /* Fetch whether they're turning break on or off. */
- if (get_user(on, input) != 0)
- return -EFAULT;
+static int add_eventfd(struct lguest *lg, unsigned long addr, int fd)
+{
+ struct lg_eventfd_map *new, *old = lg->eventfds;
- if (on) {
- cpu->break_out = 1;
- /* Pop it out of the Guest (may be running on different CPU) */
- wake_up_process(cpu->tsk);
- /* Wait for them to reset it */
- return wait_event_interruptible(cpu->break_wq, !cpu->break_out);
- } else {
- cpu->break_out = 0;
- wake_up(&cpu->break_wq);
- return 0;
+ if (!addr)
+ return -EINVAL;
+
+ /* Replace the old array with the new one, carefully: others can
+ * be accessing it at the same time */
+ new = kmalloc(sizeof(*new) + sizeof(new->map[0]) * (old->num + 1),
+ GFP_KERNEL);
+ if (!new)
+ return -ENOMEM;
+
+ /* First make identical copy. */
+ memcpy(new->map, old->map, sizeof(old->map[0]) * old->num);
+ new->num = old->num;
+
+ /* Now append new entry. */
+ new->map[new->num].addr = addr;
+ new->map[new->num].event = eventfd_fget(fd);
+ if (IS_ERR(new->map[new->num].event)) {
+ kfree(new);
+ return PTR_ERR(new->map[new->num].event);
}
+ new->num++;
+
+ /* Now put new one in place. */
+ rcu_assign_pointer(lg->eventfds, new);
+
+ /* We're not in a big hurry. Wait until noone's looking at old
+ * version, then delete it. */
+ synchronize_rcu();
+ kfree(old);
+
+ return 0;
+}
+
+static int attach_eventfd(struct lguest *lg, const unsigned long __user *input)
+{
+ unsigned long addr, fd;
+ int err;
+
+ if (get_user(addr, input) != 0)
+ return -EFAULT;
+ input++;
+ if (get_user(fd, input) != 0)
+ return -EFAULT;
+
+ mutex_lock(&lguest_lock);
+ err = add_eventfd(lg, addr, fd);
+ mutex_unlock(&lguest_lock);
+
+ return 0;
}
/*L:050 Sending an interrupt is done by writing LHREQ_IRQ and an interrupt
@@ -45,9 +96,8 @@ static int user_send_irq(struct lg_cpu *cpu, const unsigned long __user *input)
return -EFAULT;
if (irq >= LGUEST_IRQS)
return -EINVAL;
- /* Next time the Guest runs, the core code will see if it can deliver
- * this interrupt. */
- set_bit(irq, cpu->irqs_pending);
+
+ set_interrupt(cpu, irq);
return 0;
}
@@ -126,9 +176,6 @@ static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip)
* address. */
lguest_arch_setup_regs(cpu, start_ip);
- /* Initialize the queue for the Waker to wait on */
- init_waitqueue_head(&cpu->break_wq);
-
/* We keep a pointer to the Launcher task (ie. current task) for when
* other Guests want to wake this one (eg. console input). */
cpu->tsk = current;
@@ -185,6 +232,13 @@ static int initialize(struct file *file, const unsigned long __user *input)
goto unlock;
}
+ lg->eventfds = kmalloc(sizeof(*lg->eventfds), GFP_KERNEL);
+ if (!lg->eventfds) {
+ err = -ENOMEM;
+ goto free_lg;
+ }
+ lg->eventfds->num = 0;
+
/* Populate the easy fields of our "struct lguest" */
lg->mem_base = (void __user *)args[0];
lg->pfn_limit = args[1];
@@ -192,7 +246,7 @@ static int initialize(struct file *file, const unsigned long __user *input)
/* This is the first cpu (cpu 0) and it will start booting at args[2] */
err = lg_cpu_start(&lg->cpus[0], 0, args[2]);
if (err)
- goto release_guest;
+ goto free_eventfds;
/* Initialize the Guest's shadow page tables, using the toplevel
* address the Launcher gave us. This allocates memory, so can fail. */
@@ -211,7 +265,9 @@ static int initialize(struct file *file, const unsigned long __user *input)
free_regs:
/* FIXME: This should be in free_vcpu */
free_page(lg->cpus[0].regs_page);
-release_guest:
+free_eventfds:
+ kfree(lg->eventfds);
+free_lg:
kfree(lg);
unlock:
mutex_unlock(&lguest_lock);
@@ -252,11 +308,6 @@ static ssize_t write(struct file *file, const char __user *in,
/* Once the Guest is dead, you can only read() why it died. */
if (lg->dead)
return -ENOENT;
-
- /* If you're not the task which owns the Guest, all you can do
- * is break the Launcher out of running the Guest. */
- if (current != cpu->tsk && req != LHREQ_BREAK)
- return -EPERM;
}
switch (req) {
@@ -264,8 +315,8 @@ static ssize_t write(struct file *file, const char __user *in,
return initialize(file, input);
case LHREQ_IRQ:
return user_send_irq(cpu, input);
- case LHREQ_BREAK:
- return break_guest_out(cpu, input);
+ case LHREQ_EVENTFD:
+ return attach_eventfd(lg, input);
default:
return -EINVAL;
}
@@ -303,6 +354,12 @@ static int close(struct inode *inode, struct file *file)
* the Launcher's memory management structure. */
mmput(lg->cpus[i].mm);
}
+
+ /* Release any eventfds they registered. */
+ for (i = 0; i < lg->eventfds->num; i++)
+ fput(lg->eventfds->map[i].event);
+ kfree(lg->eventfds);
+
/* If lg->dead doesn't contain an error code it will be NULL or a
* kmalloc()ed string, either of which is ok to hand to kfree(). */
if (!IS_ERR(lg->dead))