[PATCH v2 04/13] KVM: selftests: Assert that vcpu_{g,s}et_reg() won't truncate

[Sean Christopherson <seanjc@xxxxxxxxxx>]

Assert that the the register being read/written by vcpu_{g,s}et_reg() is
no larger than a uint64_t, i.e. that a selftest isn't unintentionally
truncating the value being read/written.

Ideally, the assert would be done at compile-time, but that would limit
the checks to hardcoded accesses and/or require fancier compile-time
assertion infrastructure to filter out dynamic usage.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
 tools/testing/selftests/kvm/include/kvm_util.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index 429a7f003fe3..80230e49e35f 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -683,6 +683,8 @@ static inline uint64_t vcpu_get_reg(struct kvm_vcpu *vcpu, uint64_t id)
 	uint64_t val;
 	struct kvm_one_reg reg = { .id = id, .addr = (uint64_t)&val };
 
+	TEST_ASSERT(KVM_REG_SIZE(id) <= sizeof(val), "Reg %lx too big", id);
+
 	vcpu_ioctl(vcpu, KVM_GET_ONE_REG, &reg);
 	return val;
 }
@@ -690,6 +692,8 @@ static inline void vcpu_set_reg(struct kvm_vcpu *vcpu, uint64_t id, uint64_t val
 {
 	struct kvm_one_reg reg = { .id = id, .addr = (uint64_t)&val };
 
+	TEST_ASSERT(KVM_REG_SIZE(id) <= sizeof(val), "Reg %lx too big", id);
+
 	vcpu_ioctl(vcpu, KVM_SET_ONE_REG, &reg);
 }
 
-- 
2.46.0.598.g6f2099f65c-goog