KVM: arm64: selftests: Provide helper for getting default vCPU target

The default vCPU target in KVM selftests is pretty boring in that it
doesn't enable any vCPU features. Expose a helper for getting the
default target to prepare for cramming in more features. Call
KVM_ARM_PREFERRED_TARGET directly from get-reg-list as it needs
fine-grained control over feature flags.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Itaru Kitayama <itaru.kitayama@fujitsu.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>

Author: oupton

tools/testing/selftests/kvm/arm64/psci_test.c

@@ -89,7 +89,7 @@ static struct kvm_vm *setup_vm(void *guest_code, struct kvm_vcpu **source,
 
 	vm = vm_create(2);
 
-	vm_ioctl(vm, KVM_ARM_PREFERRED_TARGET, &init);
+	kvm_get_default_vcpu_target(vm, &init);
 	init.features[0] |= (1 << KVM_ARM_VCPU_PSCI_0_2);
 
 	*source = aarch64_vcpu_add(vm, 0, &init, guest_code);

tools/testing/selftests/kvm/arm64/smccc_filter.c

@@ -64,7 +64,7 @@ static struct kvm_vm *setup_vm(struct kvm_vcpu **vcpu)
 	struct kvm_vm *vm;
 
 	vm = vm_create(1);
-	vm_ioctl(vm, KVM_ARM_PREFERRED_TARGET, &init);
+	kvm_get_default_vcpu_target(vm, &init);
 
 	/*
 	 * Enable in-kernel emulation of PSCI to ensure that calls are denied

tools/testing/selftests/kvm/arm64/vpmu_counter_access.c

@@ -430,7 +430,7 @@ static void create_vpmu_vm(void *guest_code)
 	}
 
 	/* Create vCPU with PMUv3 */
-	vm_ioctl(vpmu_vm.vm, KVM_ARM_PREFERRED_TARGET, &init);
+	kvm_get_default_vcpu_target(vpmu_vm.vm, &init);
 	init.features[0] |= (1 << KVM_ARM_VCPU_PMU_V3);
 	vpmu_vm.vcpu = aarch64_vcpu_add(vpmu_vm.vm, 0, &init, guest_code);
 	vcpu_init_descriptor_tables(vpmu_vm.vcpu);
@@ -525,7 +525,7 @@ static void run_access_test(uint64_t pmcr_n)
 	 * Reset and re-initialize the vCPU, and run the guest code again to
 	 * check if PMCR_EL0.N is preserved.
 	 */
-	vm_ioctl(vpmu_vm.vm, KVM_ARM_PREFERRED_TARGET, &init);
+	kvm_get_default_vcpu_target(vpmu_vm.vm, &init);
 	init.features[0] |= (1 << KVM_ARM_VCPU_PMU_V3);
 	aarch64_vcpu_setup(vcpu, &init);
 	vcpu_init_descriptor_tables(vcpu);

tools/testing/selftests/kvm/get-reg-list.c

@@ -116,21 +116,24 @@ void __weak finalize_vcpu(struct kvm_vcpu *vcpu, struct vcpu_reg_list *c)
 }
 
 #ifdef __aarch64__
-static void prepare_vcpu_init(struct vcpu_reg_list *c, struct kvm_vcpu_init *init)
+static void prepare_vcpu_init(struct kvm_vm *vm, struct vcpu_reg_list *c,
+			      struct kvm_vcpu_init *init)
 {
 	struct vcpu_reg_sublist *s;
 
+	vm_ioctl(vm, KVM_ARM_PREFERRED_TARGET, init);
+
 	for_each_sublist(c, s)
 		if (s->capability)
 			init->features[s->feature / 32] |= 1 << (s->feature % 32);
 }
 
 static struct kvm_vcpu *vcpu_config_get_vcpu(struct vcpu_reg_list *c, struct kvm_vm *vm)
 {
-	struct kvm_vcpu_init init = { .target = -1, };
+	struct kvm_vcpu_init init;
 	struct kvm_vcpu *vcpu;
 
-	prepare_vcpu_init(c, &init);
+	prepare_vcpu_init(vm, c, &init);
 	vcpu = __vm_vcpu_add(vm, 0);
 	aarch64_vcpu_setup(vcpu, &init);
 

tools/testing/selftests/kvm/include/arm64/processor.h

@@ -357,4 +357,6 @@ static __always_inline u64 ctxt_reg_alias(struct kvm_vcpu *vcpu, u32 encoding)
 	return KVM_ARM64_SYS_REG(alias);
 }
 
+void kvm_get_default_vcpu_target(struct kvm_vm *vm, struct kvm_vcpu_init *init);
+
 #endif /* SELFTEST_KVM_PROCESSOR_H */

tools/testing/selftests/kvm/lib/arm64/processor.c

@@ -267,19 +267,24 @@ void virt_arch_dump(FILE *stream, struct kvm_vm *vm, uint8_t indent)
 	}
 }
 
+void kvm_get_default_vcpu_target(struct kvm_vm *vm, struct kvm_vcpu_init *init)
+{
+	struct kvm_vcpu_init preferred = {};
+
+	vm_ioctl(vm, KVM_ARM_PREFERRED_TARGET, &preferred);
+
+	*init = preferred;
+}
+
 void aarch64_vcpu_setup(struct kvm_vcpu *vcpu, struct kvm_vcpu_init *init)
 {
 	struct kvm_vcpu_init default_init = { .target = -1, };
 	struct kvm_vm *vm = vcpu->vm;
 	uint64_t sctlr_el1, tcr_el1, ttbr0_el1;
 
-	if (!init)
+	if (!init) {
+		kvm_get_default_vcpu_target(vm, &default_init);
 		init = &default_init;
-
-	if (init->target == -1) {
-		struct kvm_vcpu_init preferred;
-		vm_ioctl(vm, KVM_ARM_PREFERRED_TARGET, &preferred);
-		init->target = preferred.target;
 	}
 
 	vcpu_ioctl(vcpu, KVM_ARM_VCPU_INIT, init);