Messages in this thread |  | | | Date | Wed, 09 May 2012 07:03:37 -0700 | | From | "H. Peter Anvin" <> | | Subject | Re: [PATCH] bitops: add _local bitops |
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On 05/09/2012 06:45 AM, Michael S. Tsirkin wrote: > kvm needs to update some hypervisor variables atomically > in a sense that the operation can't be interrupted > in the middle. However the hypervisor always runs > on the same CPU so it does not need any memory > barrier or lock prefix. > > At Peter Anvin's suggestion, add _local bitops for this purpose: > define them as non-atomics for x86 and (for now) atomics > for everyone else. > > Uses are not restricted to virtualization: they > might be useful to communicate with an interrupt > handler if we know that it's running on the same CPU. > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
I don't think you can use the x86 nonatomics as-is, because they don't contain optimization barriers.
-hpa
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