[PATCH] ARM64: KVM: Fix coherent_icache_guest_page() for host with external L3-cache.

[Will Deacon]

On Fri, Aug 30, 2013 at 03:22:11PM +0100, Marc Zyngier wrote:
> On 2013-08-30 15:04, Catalin Marinas wrote:
> > On Fri, Aug 30, 2013 at 02:21:57PM +0100, Marc Zyngier wrote:
> >> On 2013-08-30 11:44, Anup Patel wrote:
> >> > For KVM, we can avoid flushing d-cache to PoC every time in
> >> > coherent_icache_guest_page() by only doing it when Guest MMU is
> >> > turned-off. This may reduce the performance penalty.
> >>
> >> What about the I and C bits in SCTLR_EL1? Does L3 also honour these
> >> bits?
> >
> > I would think so, it probably cares about how the transactions are
> > presented at the bus level by the CPU.
> 
> That'd make sense indeed. So we need to track both SCTLR_EL1.{I,C,M} in 
> order to find out whether or not we need to clean the cache.

<horrible hack>
Could you use a dummy ATS_* operation, then read the cacheability attributes
out of the PAR?
</horrible hack>

Will