[Xen-devel] [PATCH for-4.12 v2] arm: gic-v3: deactivate SGI/PPI during initialization

[Peng Fan <peng.fan@xxxxxxx>]

On i.MX8, we implemented partition reboot which means Cortex-A reboot
will not impact M4 cores and System control Unit core. However GICv3
is not reset because we also need to support A72 Cluster reboot without
affecting A53 Cluster.

The gic-v3 controller is configured with EOImode to 1, so during xen
reboot, there is a function call "smp_call_function(halt_this_cpu, NULL, 0);"
, but halt_this_cpu never return, that means other CPUs have no chance to
deactivate the SGI interrupt, because the deactivate_irq operation is at
the end of do_sgi. During the next boot of Xen, CPU0 will issue
GIC_SGI_CALL_FUNCTION to other CPUs. As the Active state for SGI is left
untouched during the reboot, the GIC_SGI_CALL_FUNCTION will still be active
on the non-boot CPUs. This means the interrupt cannot be triggered again
until it get deactivated.

And according to IHI0069D_gic_architecture_specification, chapter
"8.11.3 GICR_ICACTIVER0, Interrupt Clear-Active Register 0", the RW
field of GICR_ICACTIVER0 resets to a value that is architecturally UNKNOWN.

So set a fixed value during gic-v3 initialization to make sure
interrupts are in deactivated state.

Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
---

V2:
  refine commit log
  deactivate SGI/PPI.
  No need for SPI, because Some or all RW fields of this GICD_ICACTIVER
  have defined reset values

 xen/arch/arm/gic-v3.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
index 6fbc106757..1c1d2604f3 100644
--- a/xen/arch/arm/gic-v3.c
+++ b/xen/arch/arm/gic-v3.c
@@ -833,6 +833,11 @@ static int gicv3_cpu_init(void)
         writel_relaxed(priority,
                 GICD_RDIST_SGI_BASE + GICR_IPRIORITYR0 + (i / 4) * 4);
 
+    /*
+     * The activate state is unknown at boot, so make sure all
+     * SGIs and PPIs are de-activated.
+     */
+    writel_relaxed(0xffffffff, GICD_RDIST_SGI_BASE + GICR_ICACTIVER0);
     /*
      * Disable all PPI interrupts, ensure all SGI interrupts are
      * enabled.
-- 
2.14.1


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