From: Tom Rini <trini@konsulko.com>
To: Andre Przywara <andre.przywara@arm.com>
Cc: Peter Hoyes <peter.hoyes@arm.com>,
u-boot@lists.denx.de, patrick.delaunay@foss.st.com,
sjg@chromium.org, diego.sueiro@arm.com
Subject: Re: [PATCH v2 5/6] arm: Use armv8_switch_to_el1 env to switch to EL1
Date: Thu, 2 Sep 2021 19:49:17 -0400 [thread overview]
Message-ID: <20210902234917.GG858@bill-the-cat> (raw)
In-Reply-To: <20210903000628.4419ad1f@slackpad.fritz.box>
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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@konsulko.com> wrote:
>
> Hi Tom,
>
> > On Thu, Aug 19, 2021 at 04:53:13PM +0100, Peter Hoyes wrote:
> >
> > > From: Peter Hoyes <Peter.Hoyes@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@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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next prev parent reply other threads:[~2021-09-02 23:49 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-19 15:53 [PATCH v2 0/6] Armv8r64 + BASER_FVP board support Peter Hoyes
2021-08-19 15:53 ` [PATCH v2 1/6] armv8: Disable pointer authentication traps for EL1 Peter Hoyes
2021-08-20 14:44 ` Andre Przywara
2021-08-20 15:04 ` Michael Walle
2021-09-02 22:41 ` Tom Rini
2021-08-19 15:53 ` [PATCH v2 2/6] armv8: Ensure EL1&0 VMSA is enabled Peter Hoyes
2021-09-02 22:41 ` Tom Rini
2021-08-19 15:53 ` [PATCH v2 3/6] armv8: Add ARMv8 MPU configuration logic Peter Hoyes
2021-08-20 15:22 ` Andre Przywara
2021-09-02 22:41 ` Tom Rini
2021-08-19 15:53 ` [PATCH v2 4/6] vexpress64: Add BASER_FVP vexpress board variant Peter Hoyes
2021-09-02 22:42 ` Tom Rini
2021-08-19 15:53 ` [PATCH v2 5/6] arm: Use armv8_switch_to_el1 env to switch to EL1 Peter Hoyes
2021-08-20 16:57 ` Andre Przywara
2021-08-20 17:05 ` Tom Rini
2021-08-26 11:36 ` Andre Przywara
2021-09-02 22:42 ` Tom Rini
2021-09-02 23:07 ` Andre Przywara
2021-09-02 23:49 ` Tom Rini [this message]
2021-09-03 10:19 ` Peter Hoyes
2021-09-03 14:00 ` Tom Rini
2021-08-19 15:53 ` [PATCH v2 6/6] doc: Add documentation for the Arm vexpress board configs Peter Hoyes
2021-09-02 22:42 ` Tom Rini
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