1 files changed, 27 insertions, 15 deletions

diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
index fc8487564d1f..ae075dc0890d 100644
--- a/virt/kvm/coalesced_mmio.c
+++ b/virt/kvm/coalesced_mmio.c
@@ -25,23 +25,8 @@ static int coalesced_mmio_in_range(struct kvm_coalesced_mmio_dev *dev,
                                    gpa_t addr, int len)
 {
         struct kvm_coalesced_mmio_zone *zone;
-        struct kvm_coalesced_mmio_ring *ring;
-        unsigned avail;
         int i;
 
-        /* Are we able to batch it ? */
-
-        /* last is the first free entry
-         * check if we don't meet the first used entry
-         * there is always one unused entry in the buffer
-         */
-        ring = dev->kvm->coalesced_mmio_ring;
-        avail = (ring->first - ring->last - 1) % KVM_COALESCED_MMIO_MAX;
-        if (avail < KVM_MAX_VCPUS) {
-                /* full */
-                return 0;
-        }
-
         /* is it in a batchable area ? */
 
         for (i = 0; i < dev->nb_zones; i++) {
@@ -58,16 +43,43 @@ static int coalesced_mmio_in_range(struct kvm_coalesced_mmio_dev *dev,
         return 0;
 }
 
+static int coalesced_mmio_has_room(struct kvm_coalesced_mmio_dev *dev)
+{
+        struct kvm_coalesced_mmio_ring *ring;
+        unsigned avail;
+
+        /* Are we able to batch it ? */
+
+        /* last is the first free entry
+         * check if we don't meet the first used entry
+         * there is always one unused entry in the buffer
+         */
+        ring = dev->kvm->coalesced_mmio_ring;
+        avail = (ring->first - ring->last - 1) % KVM_COALESCED_MMIO_MAX;
+        if (avail == 0) {
+                /* full */
+                return 0;
+        }
+
+        return 1;
+}
+
 static int coalesced_mmio_write(struct kvm_io_device *this,
                                 gpa_t addr, int len, const void *val)
 {
         struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
         struct kvm_coalesced_mmio_ring *ring = dev->kvm->coalesced_mmio_ring;
+
         if (!coalesced_mmio_in_range(dev, addr, len))
                 return -EOPNOTSUPP;
 
         spin_lock(&dev->lock);
 
+        if (!coalesced_mmio_has_room(dev)) {
+                spin_unlock(&dev->lock);
+                return -EOPNOTSUPP;
+        }
+
         /* copy data in first free entry of the ring */
 
         ring->coalesced_mmio[ring->last].phys_addr = addr;