Re: [Qemu-devel] [PATCH 04/30] add a header file for atomic operations

[Paolo Bonzini]

Il 28/06/2013 22:41, Anthony Liguori ha scritto:
> Tiny copy/paste error here: s/qemu memory/memory/g".
> 
> One thing I've been thinking about reviewing this code, what should we
> be doing in virtio.c?
> 
> We have barriers but we're relying on st[u][wlb]_phys having atomic
> semantics.  I think it's okay in practice but if we're taking a more
> diligent approach here should we introduce atomic variants that work on
> guest phys addresses?

I think it's part of the semantics of stu?[wlb]_phys that they (a) are
not CSE'd by the compiler (b) are atomic for aligned addresses.  I
cannot find the commit exactly, but I think mst added specific code for
that.

Paolo