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

[grygorii.strashko@ti.com (Grygorii Strashko)]

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:
>> On Tue, Jun 30, 2015 at 11:44:22AM +0100, Grygorii Strashko wrote:
>>> 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 <nico@linaro.org>
>>> Cc: Santosh Shilimkar <ssantosh@kernel.org>
>>> Cc: Vitaly Andrianov <vitalya@ti.com>
>>> 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.



>>
>> 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