[PATCH] ARM: psci: boot_secondary: replace __pa with virt_to_idmap

Hi,

On 06/30/2015 11:25 PM, Russell King - ARM Linux wrote:

On Tue, Jun 30, 2015 at 05:18:37PM +0100, Mark Rutland wrote:

quoted

On Tue, Jun 30, 2015 at 11:44:22AM +0100, Grygorii Strashko wrote:

quoted

On some PAE systems (e.g. TI Keystone), memory is above the 32-bit
addressable limit, and the interconnect provides an aliased view of
parts of physical memory in the 32-bit addressable space. This alias
is strictly for boot time usage, and is not otherwise usable because
of coherency limitations.

On such systems, the idmap mechanism has to be used to pass correct
boot address of secondary CPU to FW.
virt_to_idmap() will fall-back to existing virt_to_phys() macro if
such conversation is not required.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Nicolas Pitre <redacted>
Cc: Santosh Shilimkar <ssantosh@kernel.org>
Cc: Vitaly Andrianov <redacted>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
---
  arch/arm/kernel/psci_smp.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

The code itself looks sane to me, though the commit message would be
better with Russell's suggested rewording.

This will also conflict with my migration to a common PSCI client
implementation [1,2] (especially given the absence of virt_to_idmap on
arm64), but I'm happy to fold it in or rebase atop of it.

I saw your series in lists, but, seems, It is not in next (4.2).
Therefor I've not tried to base this patch on top of your series, but
you can reuse/squash it as you think is better.

quoted

Russell, are you able to take a look at the migration patch [2]? How
would you prefer for the two patches to be taken?

Well, the first thing that stands out about patch [2] is that it's
introducing a load of magic hex numbers, where before we had a struct
with nice definitions.  (I'm thinking about highbank_suspend_finish()
and calxeda_idle_finish().)  This seems to be a backwards step.

There's two options on how to handle this.  Either accept the
virt_to_idmap() change first, and then sort out the resulting difference,
maybe by having ARM64 grow a virt_to_idmap() of its own (which is just
a virt_to_phys()) or we do it the other way around.  Either way, we
need a new macro, and the established name for it is virt_to_idmap().
The order doesn't matter as the end result would be the same.

There is another advantage to keep this patch as is -
as a fix it can be back-ported to stable trees (at least in 4.1, but
probably even in v3.13.

psci_smp.c added in v3.11
virt_to_idmap added in v3.13



-- 
regards,
-grygorii