[PATCH v2 5/6] arm: Use armv8_switch_to_el1 env to switch to EL1

[Tom Rini]

On Fri, Sep 03, 2021 at 12:07:20AM +0100, Andre Przywara wrote:
> On Thu, 2 Sep 2021 18:42:05 -0400
> Tom Rini <trini at konsulko.com> wrote:
> 
> Hi Tom,
> 
> > On Thu, Aug 19, 2021 at 04:53:13PM +0100, Peter Hoyes wrote:
> > 
> > > From: Peter Hoyes <Peter.Hoyes at arm.com>
> > > 
> > > Use the environment variable armv8_switch_to_el1 to determine whether
> > > to switch to EL1 at runtime. This is an alternative to the
> > > CONFIG_ARMV8_SWITCH_TO_EL1 compile-time option.
> > > 
> > > The environment variable will be ineffective if the ARMV8_MULTIENTRY
> > > config is used.
> > > 
> > > This is required by the Armv8r64 architecture, which must be able to
> > > boot at S-EL1 for Linux but may need to boot at other ELs for other
> > > systems.
> > > 
> > > Signed-off-by: Peter Hoyes <Peter.Hoyes at arm.com>  
> > 
> > Applied to u-boot/next, thanks!
> 
> Sorry for keeping silent on this, we had some internal discussions
> here, and we don't think this is the right approach.

Well, oops on my part too.

> This whole CONFIG_ARMV8_SWITCH_TO_EL1 solution is actually already
> questionable, as it goes somewhat against the PSCI spec, which requires
> secondaries to enter in the highest non-secure exception level (Section
> 6.1.3: "... As described in Figure 6, the return Exception level for a
> CPU_ON call is the highest Non secure Exception level implemented.")
> 
> In any case the primary core must enter an the same exception level as
> the secondaries, or all hell breaks loose. The current code violates
> this bluntly when the dynamic method is used (as the spin table code
> doesn't know about this variable).
> 
> So can you please revert this patch? We are looking into a different

Should I undo just this, or the whole vexpress_aemv8r series?

-- 
Tom
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