Move the check whether there are available entries to within the spinlock.
This allows working with larger amount of VCPUs and reduces premature
exits when using a large number of VCPUs.
Cc: Avi Kivity <avi@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Signed-off-by: Sasha Levin <levinsasha928@xxxxxxxxx>
---
virt/kvm/coalesced_mmio.c | 42 +++++++++++++++++++++++++++---------------
1 files changed, 27 insertions(+), 15 deletions(-)
diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
index fc84875..ae075dc 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;
--
1.7.6
--
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