[RFC PATCH 24/26] kvm: arm64: Keep nVHE EL2 vector installed

[David Brazdil <dbrazdil@google.com>]

KVM by default keeps the stub vector installed and installs the nVHE
vector only briefly for init and later on demand. Change this policy
to install the vector at init and then never uninstall it.

Signed-off-by: David Brazdil <dbrazdil@google.com>
---
 arch/arm64/kvm/arm.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 6fbda652200b..3dff6af69eca 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -64,6 +64,11 @@ static bool vgic_present;
 static DEFINE_PER_CPU(unsigned char, kvm_arm_hardware_enabled);
 DEFINE_STATIC_KEY_FALSE(userspace_irqchip_in_use);
 
+static bool keep_hyp_installed(void)
+{
+	return !is_kernel_in_hyp_mode();
+}
+
 int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
 {
 	return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
@@ -1430,7 +1435,8 @@ static void _kvm_arch_hardware_disable(void *discard)
 
 void kvm_arch_hardware_disable(void)
 {
-	_kvm_arch_hardware_disable(NULL);
+	if (!keep_hyp_installed())
+		_kvm_arch_hardware_disable(NULL);
 }
 
 #ifdef CONFIG_CPU_PM
@@ -1473,11 +1479,13 @@ static struct notifier_block hyp_init_cpu_pm_nb = {
 
 static void __init hyp_cpu_pm_init(void)
 {
-	cpu_pm_register_notifier(&hyp_init_cpu_pm_nb);
+	if (!keep_hyp_installed())
+		cpu_pm_register_notifier(&hyp_init_cpu_pm_nb);
 }
 static void __init hyp_cpu_pm_exit(void)
 {
-	cpu_pm_unregister_notifier(&hyp_init_cpu_pm_nb);
+	if (!keep_hyp_installed())
+		cpu_pm_unregister_notifier(&hyp_init_cpu_pm_nb);
 }
 #else
 static inline void hyp_cpu_pm_init(void)
@@ -1580,7 +1588,8 @@ static int init_subsystems(void)
 	kvm_coproc_table_init();
 
 out:
-	on_each_cpu(_kvm_arch_hardware_disable, NULL, 1);
+	if (err || !keep_hyp_installed())
+		on_each_cpu(_kvm_arch_hardware_disable, NULL, 1);
 
 	return err;
 }
-- 
2.29.1.341.ge80a0c044ae-goog