arm64: KVM: Register CPU notifiers when the kernel runs at HYP

When the kernel is running at EL2, it doesn't need init_hyp_mode() to
configure page tables for HYP. This function also registers the CPU
hotplug and lower power notifiers that cause HYP to be re-initialised
after the CPU has been reset.

To avoid losing the register state that controls stage2 translation, move
the registering of these notifiers into init_subsystems(), and add a
is_kernel_in_hyp_mode() path to each callback.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Fixes: 1e947bad0b6 ("arm64: KVM: Skip HYP setup when already running in HYP")
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 6accd66..b538431 100644 (file)
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -1061,15 +1061,27 @@ static void cpu_init_hyp_mode(void *dummy)
        kvm_arm_init_debug();
 }
 
+static void cpu_hyp_reinit(void)
+{
+       if (is_kernel_in_hyp_mode()) {
+               /*
+                * cpu_init_stage2() is safe to call even if the PM
+                * event was cancelled before the CPU was reset.
+                */
+               cpu_init_stage2(NULL);
+       } else {
+               if (__hyp_get_vectors() == hyp_default_vectors)
+                       cpu_init_hyp_mode(NULL);
+       }
+}
+
 static int hyp_init_cpu_notify(struct notifier_block *self,
                               unsigned long action, void *cpu)
 {
        switch (action) {
        case CPU_STARTING:
        case CPU_STARTING_FROZEN:
-               if (__hyp_get_vectors() == hyp_default_vectors)
-                       cpu_init_hyp_mode(NULL);
-               break;
+               cpu_hyp_reinit();
        }
 
        return NOTIFY_OK;
@@ -1084,9 +1096,8 @@ static int hyp_init_cpu_pm_notifier(struct notifier_block *self,
                                    unsigned long cmd,
                                    void *v)
 {
-       if (cmd == CPU_PM_EXIT &&
-           __hyp_get_vectors() == hyp_default_vectors) {
-               cpu_init_hyp_mode(NULL);
+       if (cmd == CPU_PM_EXIT) {
+               cpu_hyp_reinit();
                return NOTIFY_OK;
        }
 
@@ -1128,6 +1139,22 @@ static int init_subsystems(void)
        int err;
 
        /*
+        * Register CPU Hotplug notifier
+        */
+       cpu_notifier_register_begin();
+       err = __register_cpu_notifier(&hyp_init_cpu_nb);
+       cpu_notifier_register_done();
+       if (err) {
+               kvm_err("Cannot register KVM init CPU notifier (%d)\n", err);
+               return err;
+       }
+
+       /*
+        * Register CPU lower-power notifier
+        */
+       hyp_cpu_pm_init();
+
+       /*
         * Init HYP view of VGIC
         */
        err = kvm_vgic_hyp_init();
@@ -1270,19 +1297,6 @@ static int init_hyp_mode(void)
        free_boot_hyp_pgd();
 #endif
 
-       cpu_notifier_register_begin();
-
-       err = __register_cpu_notifier(&hyp_init_cpu_nb);
-
-       cpu_notifier_register_done();
-
-       if (err) {
-               kvm_err("Cannot register HYP init CPU notifier (%d)\n", err);
-               goto out_err;
-       }
-
-       hyp_cpu_pm_init();
-
        /* set size of VMID supported by CPU */
        kvm_vmid_bits = kvm_get_vmid_bits();
        kvm_info("%d-bit VMID\n", kvm_vmid_bits);