Re: [Xen-devel] [PATCH v2] tools: libxc: flush data cache after loading images into guest memory

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2013-12-12 at 14:30 +0000, Stefano Stabellini wrote:
> On Thu, 12 Dec 2013, Ian Campbell wrote:
> > On ARM guest OSes are started with MMU and Caches disables (as they are on
> > native) however caching is enabled in the domain running the builder and
> > therefore we must flush the cache as we load the blobs, otherwise when the
> > guest starts running it may not see them. The dom0 build in the hypervisor 
> > has
> > the same requirements and already does the right thing.
> > 
> > The mechanism for performing a cache flush from userspace is OS specific, so
> > implement this as a new osdep hook:
> > 
> >  - On 32-bit ARM Linux provides a system call to flush the cache.
> >  - On 64-bit ARM Linux the processor is configured to allow cache flushes
> >    directly from userspace.
> >  - Non-Linux platforms will need to provide their own implementation. If
> >    similar mechanisms are not available then a new privcmd ioctl should be a
> >    suitable alternative.
> > 
> > No cache maintenance is required on x86, so provide a stub for all non-Linux
> > platforms which returns success on x86 only and log an error otherwise.
> > 
> > This fixes guest building on Xgene which has a very large L3 cache and so is
> > particularly susceptible to this problem. It has also been observed
> > sporadically on midway.
> > 
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > Cc: Andre Przywara <andre.przywara@xxxxxxxxxxx>
> > Cc: Pranavkumar Sawargaonkar <psawargaonkar@xxxxxxx>
> > Cc: Anup Patel <apatel@xxxxxxx>
> 
> Looks good to me

Is that an Ack?



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