New subject: [RFC] Api to power down all cores

21 Aug 2020

Hi Soby,
 I realize using term 'PSCI API' in rfc tag is misleading like Achin
mentioned in gerrit.
Here I wanted to have a generic API to 'stop_other_cores'  in secure world.
The usage is platform firmware specific.
 Implementation of 'stop_other_cores'  depends on a generic 'IPI' support
(1).
 It leverages the existing EHF. So I feel it is not adding and complexity or
overhead in normal execution path.
'stop_other_cores'  API implementation depends on some psci private
functions to traverse the pd nodes and
extract MPIDRs for target pe list. That was the reason to put the function
within psci lib. So there are two things.
1- Does this idea of  'stop_other_core' api qualify to be generic
2- Does a generic IPI layer make sense
Thanks
Sandeep
...
-----Original Message-----
From: Soby Mathew [mailto:Soby.Mathew@arm.com]
Sent: Thursday, August 20, 2020 8:54 PM
To: Sandeep Tripathy
Cc: tf-a@lists.trustedfirmware.org
Subject: RE: [TF-A] [RFC] psci: api to power down all cores
Hi Sandeep,
Just to understand better, if there is a secure side panic/watchdog
interrupt,
then the secure side is already able to do such an intervention without
the
availability of a PSCI API to the NS side.
In case the NS world has crashed, then  PSCI_SYSTEM_RESET and
PSCI_SYSTEM_OFF APIs can be invoked which then does the appropriate
actions. From my reading, the PSCI specification doesn't prevent firmware
implementation of the reset and off API's from doing the kind of
implementation as per your proposal.
I intend to do 'stop_other_cores'  in platform extension of
'plat_system_resetx()',
secure side watchdog expiry/ plat_panic_handler().
...
Best Regards
Soby Mathew
...
-----Original Message-----
From: TF-A tf-a-bounces@lists.trustedfirmware.org On Behalf Of
Sandeep
...
Tripathy via TF-A
Sent: 19 August 2020 16:42
To: tf-a@lists.trustedfirmware.org
Subject: [TF-A] [RFC] psci: api to power down all cores
Hi,
   I am proposing to have a generic api in psci lib which can be used to
force
...
power down all other cores from any initiating core analogous to
'smp_cpu_stop' in linux. It is immune to interrupt lock by EL1/EL2
software.
Platforms may use this api in case of secure side panic, secure watchdog
interrupt handling or if required in certain types of warm resets. The
usage
is
...
platform dependent.
This depends on a generic implementation of secure IPI (1) which uses
EHF
to
...
handle IPI at platform defined priority. We probably require more types
of
secure IPIs.
Please review the series
Ref:
https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/5324

diff --git a/lib/psci/psci_system_off.c b/lib/psci/psci_system_off.c
index
141d69e..011aaa6 100644
--- a/lib/psci/psci_system_off.c
+++ b/lib/psci/psci_system_off.c
@@ -10,10 +10,44 @@
 #include <arch_helpers.h>
 #include <common/debug.h>
 #include <drivers/console.h>
+#include <drivers/delay_timer.h>
 #include <plat/common/platform.h>
#include "psci_private.h"
+#ifndef PLAT_CORES_PWRDWN_WAIT_TIMEOUT_MS #define
+PLAT_CORES_PWRDWN_WAIT_TIMEOUT_MS 1000 #endif



+#if IMAGE_BL31
+void psci_stop_other_cores(void)
+{
+#define PLAT_CORES_PWRDWN_WAIT_TIMEOUT_MS 1000 #endif



+#if IMAGE_BL31
+void psci_stop_other_cores(void)
+{

  int idx, this_cpu_idx, cnt;



  this_cpu_idx = plat_my_core_pos();



  /* Raise G0 IPI cpustop to all cores but self */


  for (idx = 0; idx < psci_plat_core_count; idx++) {


          if ((idx != this_cpu_idx) &&


              (psci_get_aff_info_state_by_idx(idx) ==



AFF_STATE_ON)) {



plat_ipi_send_cpu_stop(psci_cpu_pd_nodes[idx].mpidr);

          }


  }



   /* Wait for others cores to shutdown */


  for (cnt = 0; cnt < PLAT_CORES_PWRDWN_WAIT_TIMEOUT_MS; cnt++)



{
...

          if (psci_is_last_on_cpu())


                  break;


          mdelay(1);


  }



  if (!psci_is_last_on_cpu()) {


          WARN("Failed to stop all cores!\n");


          psci_print_power_domain_map();


  }



+}
+#endif



(1)
 RFC: ipi: add ipi feature
 Ref: https://review.trustedfirmware.org/c/TF-A/trusted-firmware-
a/+/5323/1
...
Thanks
Sandeep
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Re: [TF-A] [RFC] Api to power down all cores