KVM: arm/arm64: Add hook for arch-specific KVM initialisation

This patch adds a kvm_arm_init_arch_resources() hook to perform
subarch-specific initialisation when starting up KVM.

This will be used in a subsequent patch for global SVE-related
setup on arm64.

No functional change.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Tested-by: zhang.lei <zhang.lei@jp.fujitsu.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

arch/arm/include/asm/kvm_host.h

@@ -53,6 +53,8 @@
 
 DECLARE_STATIC_KEY_FALSE(userspace_irqchip_in_use);
 
+static inline int kvm_arm_init_arch_resources(void) { return 0; }
+
 u32 *kvm_vcpu_reg(struct kvm_vcpu *vcpu, u8 reg_num, u32 mode);
 int __attribute_const__ kvm_target_cpu(void);
 int kvm_reset_vcpu(struct kvm_vcpu *vcpu);

arch/arm64/include/asm/kvm_host.h

@@ -58,6 +58,8 @@
 
 DECLARE_STATIC_KEY_FALSE(userspace_irqchip_in_use);
 
+static inline int kvm_arm_init_arch_resources(void) { return 0; }
+
 int __attribute_const__ kvm_target_cpu(void);
 int kvm_reset_vcpu(struct kvm_vcpu *vcpu);
 int kvm_arch_vm_ioctl_check_extension(struct kvm *kvm, long ext);

virt/kvm/arm/arm.c

@@ -1664,6 +1664,10 @@ int kvm_arch_init(void *opaque)
 	if (err)
 		return err;
 
+	err = kvm_arm_init_arch_resources();
+	if (err)
+		return err;
+
 	if (!in_hyp_mode) {
 		err = init_hyp_mode();
 		if (err)