[PATCH 36/48] KVM: move coalesced_mmio locking to its own device

[Avi Kivity]

From: Marcelo Tosatti <mtosa...@redhat.com>

Move coalesced_mmio locking to its own device, instead of relying on
kvm->lock.

Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com>
Signed-off-by: Avi Kivity <a...@redhat.com>
---
 virt/kvm/coalesced_mmio.c |   10 ++++------
 virt/kvm/coalesced_mmio.h |    1 +
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
index 7549068..397f419 100644
--- a/virt/kvm/coalesced_mmio.c
+++ b/virt/kvm/coalesced_mmio.c
@@ -31,10 +31,6 @@ static int coalesced_mmio_in_range(struct kvm_io_device 
*this,
        if (!is_write)
                return 0;
 
-       /* kvm->lock is taken by the caller and must be not released before
-         * dev.read/write
-         */
-
        /* Are we able to batch it ? */
 
        /* last is the first free entry
@@ -43,7 +39,7 @@ static int coalesced_mmio_in_range(struct kvm_io_device *this,
         */
        ring = dev->kvm->coalesced_mmio_ring;
        avail = (ring->first - ring->last - 1) % KVM_COALESCED_MMIO_MAX;
-       if (avail < 1) {
+       if (avail < KVM_MAX_VCPUS) {
                /* full */
                return 0;
        }
@@ -70,7 +66,7 @@ static void coalesced_mmio_write(struct kvm_io_device *this,
        struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
        struct kvm_coalesced_mmio_ring *ring = dev->kvm->coalesced_mmio_ring;
 
-       /* kvm->lock must be taken by caller before call to in_range()*/
+       spin_lock(&dev->lock);
 
        /* copy data in first free entry of the ring */
 
@@ -79,6 +75,7 @@ static void coalesced_mmio_write(struct kvm_io_device *this,
        memcpy(ring->coalesced_mmio[ring->last].data, val, len);
        smp_wmb();
        ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX;
+       spin_unlock(&dev->lock);
 }
 
 static void coalesced_mmio_destructor(struct kvm_io_device *this)
@@ -101,6 +98,7 @@ int kvm_coalesced_mmio_init(struct kvm *kvm)
        dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL);
        if (!dev)
                return -ENOMEM;
+       spin_lock_init(&dev->lock);
        kvm_iodevice_init(&dev->dev, &coalesced_mmio_ops);
        dev->kvm = kvm;
        kvm->coalesced_mmio_dev = dev;
diff --git a/virt/kvm/coalesced_mmio.h b/virt/kvm/coalesced_mmio.h
index 5ac0ec6..4b49f27 100644
--- a/virt/kvm/coalesced_mmio.h
+++ b/virt/kvm/coalesced_mmio.h
@@ -12,6 +12,7 @@
 struct kvm_coalesced_mmio_dev {
        struct kvm_io_device dev;
        struct kvm *kvm;
+       spinlock_t lock;
        int nb_zones;
        struct kvm_coalesced_mmio_zone zone[KVM_COALESCED_MMIO_ZONE_MAX];
 };
-- 
1.6.3.3

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