Marcelo Tosatti wrote:
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 <mtosatti@xxxxxxxxxx>
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;
Ordering with simultaneous writes is indeed not our problem, but the
ring may contain ordered writes (even by the same vcpu!)
Suggest our own lock here. in_use is basically a homemade lock, better
to use the factory made ones which come with a warranty.
--
error compiling committee.c: too many arguments to function
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