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Re: [Xen-devel] [PATCH v2 01/18] x86/traps: factor out pv_percpu_traps_init

On Fri, May 05, 2017 at 05:12:25PM +0100, Andrew Cooper wrote:
> On 05/05/17 15:48, Wei Liu wrote:
> > The body of subarch_percpu_traps_init is for setting up PV syscall
> > trampoline. Move that into a dedicated function.
> >
> > Leave the BUILD_BUG_ON in the original function as it is not tied to PV.
> >
> > No functional change.
> >
> > Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> The trampolines are only intended to be used by PV guests, but are still
> constitute parts of Xen setting up its entrypoints in a safe manor.
> At the time I was adjusting the MSR_CSTAR handling, it was decided to
> retain it pointing at a safe location, even on hardware which shouldn't
> be able to use it.
> Therefore, my plan was to keep the trampolines as general x86
> infrastructure, and have the (lifted into C) syscall entry points gain
> something like BUG_ON(!IS_DEFINED(CONFIG_PV))

Fine by me. I will drop this patch in next version.

> ~Andrew

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