[v4 2/4] arm64: kvm: add kvm cpu hotplug

[AKASHI Takahiro]

This patch allows cpu cores to be up and down by adding
kvm_arch_hardware_enable/isable(). This way, especially in kexec case,
cores are reset to initial states and kexec can gracefully shutdown the
system and reboot a new kernel from EL2.

Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
---
 arch/arm/include/asm/kvm_host.h   |    1 -
 arch/arm/kvm/arm.c                |   29 +++++++++++++++++++----------
 arch/arm64/include/asm/kvm_host.h |    1 -
 3 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 41008cd..ca97764 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -237,7 +237,6 @@ void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
 
 struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);
 
-static inline void kvm_arch_hardware_disable(void) {}
 static inline void kvm_arch_hardware_unsetup(void) {}
 static inline void kvm_arch_sync_events(struct kvm *kvm) {}
 static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 251ab9e..e989925 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -87,11 +87,6 @@ struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void)
 	return &kvm_arm_running_vcpu;
 }
 
-int kvm_arch_hardware_enable(void)
-{
-	return 0;
-}
-
 int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
 {
 	return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
@@ -885,6 +880,9 @@ static void cpu_init_hyp_mode(void *dummy)
 	unsigned long stack_page;
 	unsigned long vector_ptr;
 
+	if (__hyp_get_vectors() != hyp_default_vectors)
+		return;
+
 	/* Switch from the HYP stub to our own HYP init vector */
 	__hyp_set_vectors(kvm_get_idmap_vector());
 
@@ -921,6 +919,10 @@ static int hyp_init_cpu_notify(struct notifier_block *self,
 		if (__hyp_get_vectors() == hyp_default_vectors)
 			cpu_init_hyp_mode(NULL);
 		break;
+	case CPU_DYING:
+	case CPU_DYING_FROZEN:
+		kvm_cpu_reset(NULL);
+		break;
 	}
 
 	return NOTIFY_OK;
@@ -936,6 +938,7 @@ static int hyp_init_cpu_pm_notifier(struct notifier_block *self,
 				    void *v)
 {
 	if (cmd == CPU_PM_EXIT &&
+	    kvm_arm_get_running_vcpu() &&
 	    __hyp_get_vectors() == hyp_default_vectors) {
 		cpu_init_hyp_mode(NULL);
 		return NOTIFY_OK;
@@ -1039,11 +1042,6 @@ static int init_hyp_mode(void)
 	}
 
 	/*
-	 * Execute the init code on each CPU.
-	 */
-	on_each_cpu(cpu_init_hyp_mode, NULL, 1);
-
-	/*
 	 * Init HYP view of VGIC
 	 */
 	err = kvm_vgic_hyp_init();
@@ -1144,6 +1142,17 @@ out_err:
 	return err;
 }
 
+int kvm_arch_hardware_enable(void)
+{
+	cpu_init_hyp_mode(NULL);
+	return 0;
+}
+
+void kvm_arch_hardware_disable(void)
+{
+	kvm_cpu_reset(NULL);
+}
+
 /* NOP: Compiling as a module not supported */
 void kvm_arch_exit(void)
 {
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 6a8da9c..831e6a4 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -262,7 +262,6 @@ static inline void vgic_arch_setup(const struct vgic_params *vgic)
 	}
 }
 
-static inline void kvm_arch_hardware_disable(void) {}
 static inline void kvm_arch_hardware_unsetup(void) {}
 static inline void kvm_arch_sync_events(struct kvm *kvm) {}
 static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
-- 
1.7.9.5