[PATCH v4 03/16] KVM: selftests: Assert that vcpu_{g,s}et_reg() won't truncate

Sean Christopherson
2024-11-28T00:59:58Z

Assert that 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.

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
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 287a3ec06df4..4c4e5a847f67 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -707,6 +707,8 @@ 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;
}
@@ -714,6 +716,8 @@ 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);
}