[patch 2/4] KVM: move coalesced_mmio locking to its own device

Marcelo Tosatti
2009-05-28T04:54:49Z

[-- Attachment #1: coalesced-mmio-lock --]
[-- Type: text/plain, Size: 2407 bytes --]

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

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: kvm-irqlock/virt/kvm/coalesced_mmio.c
===================================================================
--- kvm-irqlock.orig/virt/kvm/coalesced_mmio.c
+++ kvm-irqlock/virt/kvm/coalesced_mmio.c
@@ -26,9 +26,7 @@ static int coalesced_mmio_in_range(struc
if (!is_write)
return 0;

- /* kvm->lock is taken by the caller and must be not released before
- * dev.read/write
- */
+ spin_lock(&dev->lock);

/* Are we able to batch it ? */

@@ -41,7 +39,7 @@ static int coalesced_mmio_in_range(struc
KVM_COALESCED_MMIO_MAX;
if (next == dev->kvm->coalesced_mmio_ring->first) {
/* full */
- return 0;
+ goto out_denied;
}

/* is it in a batchable area ? */
@@ -57,6 +55,8 @@ static int coalesced_mmio_in_range(struc
addr + len <= zone->addr + zone->size)
return 1;
}
+out_denied:
+ spin_unlock(&dev->lock);
return 0;
}

@@ -67,8 +67,6 @@ static void coalesced_mmio_write(struct
(struct kvm_coalesced_mmio_dev*)this->private;
struct kvm_coalesced_mmio_ring *ring = dev->kvm->coalesced_mmio_ring;

- /* kvm->lock must be taken by caller before call to in_range()*/
-
/* copy data in first free entry of the ring */

ring->coalesced_mmio[ring->last].phys_addr = addr;
@@ -76,6 +74,7 @@ static void coalesced_mmio_write(struct
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)
@@ -90,6 +89,8 @@ int kvm_coalesced_mmio_init(struct kvm *
dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL);
if (!dev)
return -ENOMEM;
+ spin_lock_init(&dev->lock);
+
dev->dev.write = coalesced_mmio_write;
dev->dev.in_range = coalesced_mmio_in_range;
dev->dev.destructor = coalesced_mmio_destructor;
Index: kvm-irqlock/virt/kvm/coalesced_mmio.h
===================================================================
--- kvm-irqlock.orig/virt/kvm/coalesced_mmio.h
+++ kvm-irqlock/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];
};

--