Get rid of kvm->lock dependency on coalesced_mmio methods. Use an atomic variable instead to guarantee only one vcpu is batching data into the ring at a given time.
Signed-off-by: Marcelo Tosatti <[email protected]> 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 +26,12 @@ 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 - */ + /* + * Some other vcpu might be batching data into the ring, + * fallback to userspace. Ordering not our problem. + */ + if (!atomic_add_unless(&dev->in_use, 1, 1)) + return 0; /* Are we able to batch it ? */ @@ -41,7 +44,7 @@ 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 +60,8 @@ static int coalesced_mmio_in_range(struc addr + len <= zone->addr + zone->size) return 1; } +out_denied: + atomic_set(&dev->in_use, 0); return 0; } @@ -67,15 +72,14 @@ 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; ring->coalesced_mmio[ring->last].len = len; memcpy(ring->coalesced_mmio[ring->last].data, val, len); - smp_wmb(); ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX; + smp_wmb(); + atomic_set(&dev->in_use, 0); } static void coalesced_mmio_destructor(struct kvm_io_device *this) @@ -90,6 +94,8 @@ int kvm_coalesced_mmio_init(struct kvm * dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL); if (!dev) return -ENOMEM; + atomic_set(&dev->in_use, 0); + 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; + atomic_t in_use; int nb_zones; struct kvm_coalesced_mmio_zone zone[KVM_COALESCED_MMIO_ZONE_MAX]; }; -- -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
