These changes are the raw update to linux-4.4.6-rt14. Kernel sources

[kvmfornfv.git] / kernel / drivers / xen / evtchn.c

diff --git a/kernel/drivers/xen/evtchn.c b/kernel/drivers/xen/evtchn.c
index 00f40f0..38272ad 100644 (file)
--- a/kernel/drivers/xen/evtchn.c
+++ b/kernel/drivers/xen/evtchn.c
@@ -49,6 +49,8 @@
 #include <linux/init.h>
 #include <linux/mutex.h>
 #include <linux/cpu.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
 
 #include <xen/xen.h>
 #include <xen/events.h>
@@ -58,10 +60,10 @@
 struct per_user_data {
        struct mutex bind_mutex; /* serialize bind/unbind operations */
        struct rb_root evtchns;
+       unsigned int nr_evtchns;
 
        /* Notification ring, accessed via /dev/xen/evtchn. */
-#define EVTCHN_RING_SIZE     (PAGE_SIZE / sizeof(evtchn_port_t))
-#define EVTCHN_RING_MASK(_i) ((_i)&(EVTCHN_RING_SIZE-1))
+       unsigned int ring_size;
        evtchn_port_t *ring;
        unsigned int ring_cons, ring_prod, ring_overflow;
        struct mutex ring_cons_mutex; /* protect against concurrent readers */
@@ -80,10 +82,41 @@ struct user_evtchn {
        bool enabled;
 };
 
+static evtchn_port_t *evtchn_alloc_ring(unsigned int size)
+{
+       evtchn_port_t *ring;
+       size_t s = size * sizeof(*ring);
+
+       ring = kmalloc(s, GFP_KERNEL);
+       if (!ring)
+               ring = vmalloc(s);
+
+       return ring;
+}
+
+static void evtchn_free_ring(evtchn_port_t *ring)
+{
+       kvfree(ring);
+}
+
+static unsigned int evtchn_ring_offset(struct per_user_data *u,
+                                      unsigned int idx)
+{
+       return idx & (u->ring_size - 1);
+}
+
+static evtchn_port_t *evtchn_ring_entry(struct per_user_data *u,
+                                       unsigned int idx)
+{
+       return u->ring + evtchn_ring_offset(u, idx);
+}
+
 static int add_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
 {
        struct rb_node **new = &(u->evtchns.rb_node), *parent = NULL;
 
+       u->nr_evtchns++;
+
        while (*new) {
                struct user_evtchn *this;
 
@@ -107,6 +140,7 @@ static int add_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
 
 static void del_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
 {
+       u->nr_evtchns--;
        rb_erase(&evtchn->node, &u->evtchns);
        kfree(evtchn);
 }
@@ -144,8 +178,8 @@ static irqreturn_t evtchn_interrupt(int irq, void *data)
 
        spin_lock(&u->ring_prod_lock);
 
-       if ((u->ring_prod - u->ring_cons) < EVTCHN_RING_SIZE) {
-               u->ring[EVTCHN_RING_MASK(u->ring_prod)] = evtchn->port;
+       if ((u->ring_prod - u->ring_cons) < u->ring_size) {
+               *evtchn_ring_entry(u, u->ring_prod) = evtchn->port;
                wmb(); /* Ensure ring contents visible */
                if (u->ring_cons == u->ring_prod++) {
                        wake_up_interruptible(&u->evtchn_wait);
@@ -200,10 +234,10 @@ static ssize_t evtchn_read(struct file *file, char __user *buf,
        }
 
        /* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */
-       if (((c ^ p) & EVTCHN_RING_SIZE) != 0) {
-               bytes1 = (EVTCHN_RING_SIZE - EVTCHN_RING_MASK(c)) *
+       if (((c ^ p) & u->ring_size) != 0) {
+               bytes1 = (u->ring_size - evtchn_ring_offset(u, c)) *
                        sizeof(evtchn_port_t);
-               bytes2 = EVTCHN_RING_MASK(p) * sizeof(evtchn_port_t);
+               bytes2 = evtchn_ring_offset(u, p) * sizeof(evtchn_port_t);
        } else {
                bytes1 = (p - c) * sizeof(evtchn_port_t);
                bytes2 = 0;
@@ -219,7 +253,7 @@ static ssize_t evtchn_read(struct file *file, char __user *buf,
 
        rc = -EFAULT;
        rmb(); /* Ensure that we see the port before we copy it. */
-       if (copy_to_user(buf, &u->ring[EVTCHN_RING_MASK(c)], bytes1) ||
+       if (copy_to_user(buf, evtchn_ring_entry(u, c), bytes1) ||
            ((bytes2 != 0) &&
             copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
                goto unlock_out;
@@ -278,6 +312,66 @@ static ssize_t evtchn_write(struct file *file, const char __user *buf,
        return rc;
 }
 
+static int evtchn_resize_ring(struct per_user_data *u)
+{
+       unsigned int new_size;
+       evtchn_port_t *new_ring, *old_ring;
+       unsigned int p, c;
+
+       /*
+        * Ensure the ring is large enough to capture all possible
+        * events. i.e., one free slot for each bound event.
+        */
+       if (u->nr_evtchns <= u->ring_size)
+               return 0;
+
+       if (u->ring_size == 0)
+               new_size = 64;
+       else
+               new_size = 2 * u->ring_size;
+
+       new_ring = evtchn_alloc_ring(new_size);
+       if (!new_ring)
+               return -ENOMEM;
+
+       old_ring = u->ring;
+
+       /*
+        * Access to the ring contents is serialized by either the
+        * prod /or/ cons lock so take both when resizing.
+        */
+       mutex_lock(&u->ring_cons_mutex);
+       spin_lock_irq(&u->ring_prod_lock);
+
+       /*
+        * Copy the old ring contents to the new ring.
+        *
+        * If the ring contents crosses the end of the current ring,
+        * it needs to be copied in two chunks.
+        *
+        * +---------+    +------------------+
+        * |34567  12| -> |       1234567    |
+        * +-----p-c-+    +------------------+
+        */
+       p = evtchn_ring_offset(u, u->ring_prod);
+       c = evtchn_ring_offset(u, u->ring_cons);
+       if (p < c) {
+               memcpy(new_ring + c, u->ring + c, (u->ring_size - c) * sizeof(*u->ring));
+               memcpy(new_ring + u->ring_size, u->ring, p * sizeof(*u->ring));
+       } else
+               memcpy(new_ring + c, u->ring + c, (p - c) * sizeof(*u->ring));
+
+       u->ring = new_ring;
+       u->ring_size = new_size;
+
+       spin_unlock_irq(&u->ring_prod_lock);
+       mutex_unlock(&u->ring_cons_mutex);
+
+       evtchn_free_ring(old_ring);
+
+       return 0;
+}
+
 static int evtchn_bind_to_user(struct per_user_data *u, int port)
 {
        struct user_evtchn *evtchn;
@@ -305,6 +399,10 @@ static int evtchn_bind_to_user(struct per_user_data *u, int port)
        if (rc < 0)
                goto err;
 
+       rc = evtchn_resize_ring(u);
+       if (rc < 0)
+               goto err;
+
        rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, 0,
                                       u->name, evtchn);
        if (rc < 0)
@@ -503,13 +601,6 @@ static int evtchn_open(struct inode *inode, struct file *filp)
 
        init_waitqueue_head(&u->evtchn_wait);
 
-       u->ring = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
-       if (u->ring == NULL) {
-               kfree(u->name);
-               kfree(u);
-               return -ENOMEM;
-       }
-
        mutex_init(&u->bind_mutex);
        mutex_init(&u->ring_cons_mutex);
        spin_lock_init(&u->ring_prod_lock);
@@ -532,7 +623,7 @@ static int evtchn_release(struct inode *inode, struct file *filp)
                evtchn_unbind_from_user(u, evtchn);
        }
 
-       free_page((unsigned long)u->ring);
+       evtchn_free_ring(u->ring);
        kfree(u->name);
        kfree(u);