From c298125f4bc30fdbe4b7c33460ef57271cc51a7d Mon Sep 17 00:00:00 2001 From: Sasha Levin Date: Mon, 18 Jul 2011 17:17:14 +0300 Subject: KVM: MMIO: Lock coalesced device when checking for available entry 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 Cc: Ingo Molnar Cc: Marcelo Tosatti Cc: Pekka Enberg Signed-off-by: Sasha Levin Signed-off-by: Marcelo Tosatti --- virt/kvm/coalesced_mmio.c | 42 +++++++++++++++++++++++++++--------------- 1 file changed, 27 insertions(+), 15 deletions(-) (limited to 'virt') diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c index fc8487564d1..ae075dc0890 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; -- cgit v1.2.3