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

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 12 Dec 2013, Ian Campbell wrote:
> 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?

Yep, but keep in mind that I don't maintain libxc :)

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