[PATCH 07/13] KVM: arm64: selftests: Provide helper for getting default vCPU target

Oliver Upton
2025-09-17T21:21:37Z

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>
---
tools/testing/selftests/kvm/arm64/psci_test.c | 2 +-
.../testing/selftests/kvm/arm64/smccc_filter.c | 2 +-
.../selftests/kvm/arm64/vpmu_counter_access.c | 4 ++--
tools/testing/selftests/kvm/get-reg-list.c | 9 ++++++---
.../selftests/kvm/include/arm64/processor.h | 2 ++
.../testing/selftests/kvm/lib/arm64/processor.c | 17 +++++++++++------
6 files changed, 23 insertions(+), 13 deletions(-)

diff --git a/tools/testing/selftests/kvm/arm64/psci_test.c b/tools/testing/selftests/kvm/arm64/psci_test.c
index cf208390fd0e..0d4680da66d1 100644
--- a/tools/testing/selftests/kvm/arm64/psci_test.c
+++ b/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);
diff --git a/tools/testing/selftests/kvm/arm64/smccc_filter.c b/tools/testing/selftests/kvm/arm64/smccc_filter.c
index eb5551d21dbe..a8e22d866ea7 100644
--- a/tools/testing/selftests/kvm/arm64/smccc_filter.c
+++ b/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
diff --git a/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c b/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c
index 36a3a8b4e0b5..2a8f31c8e59f 100644
--- a/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c
+++ b/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);
diff --git a/tools/testing/selftests/kvm/get-reg-list.c b/tools/testing/selftests/kvm/get-reg-list.c
index 91f05f78e824..f4644c9d2d3b 100644
--- a/tools/testing/selftests/kvm/get-reg-list.c
+++ b/tools/testing/selftests/kvm/get-reg-list.c
@@ -116,10 +116,13 @@ 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);
@@ -127,10 +130,10 @@ static void prepare_vcpu_init(struct vcpu_reg_list *c, struct kvm_vcpu_init *ini

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);

diff --git a/tools/testing/selftests/kvm/include/arm64/processor.h b/tools/testing/selftests/kvm/include/arm64/processor.h
index 5a4b29c1b965..87f50efed720 100644
--- a/tools/testing/selftests/kvm/include/arm64/processor.h
+++ b/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 */
diff --git a/tools/testing/selftests/kvm/lib/arm64/processor.c b/tools/testing/selftests/kvm/lib/arm64/processor.c
index 311660a9f655..5ae65fefd48c 100644
--- a/tools/testing/selftests/kvm/lib/arm64/processor.c
+++ b/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);
--
2.47.3