ARM: kvm: prevent freeing boot_hyp_pgd when CPU_PM is selected

The boot_hyp_pgd is required to install HYP context through cpu_init_hyp_mode, on cold-boot for primary and secondary cpus, but also on the warm-boot path for secondaries (ie when a CPU is hotplugged in). On platforms with power management capabilities (eg suspend to RAM or idle-states that allow the core to enter deep idle where core is shutdown on power down entry), the boot_hyp_pgd is required to restore HYP context too upon CPU_PM notification, so the boot_hyp_pgd must not be freed to guarantee a proper HYP context restore, which in turn ensures proper core resume from low-power.

This patch adds an additional guard to free_boot_hyp_pgd() to remove its call from the kernel if CPU_PM is enabled, so that on platforms where HOTPLUG_CPU is disabled (eg UP), CPU_PM operations (suspend and CPUidle) are still guaranteed to function.

Signed-off-by Lorenzo Pieralisi <[email protected]>

Cc Christoffer Dall <[email protected]>

Cc Marc Zyngier <[email protected]>

Cc Sudeep Holla <[email protected]>

---
 arch/arm/kvm/arm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

arch/arm/kvm/arm.c +1 -1

index bc738d2..5e050c2 100644
@@ -1068,7 +1068,7 @@ static int init_hyp_mode(void)
 	if (err)
 		goto out_free_mappings;
 
-#ifndef CONFIG_HOTPLUG_CPU
+#if !defined(CONFIG_HOTPLUG_CPU) && !defined(CONFIG_CPU_PM)
 	free_boot_hyp_pgd();
 #endif
 

Signature · 1 line

2.2.1