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

Andrew Jones
2024-09-12T09:42:28Z

On Wed, Sep 11, 2024 at 01:41:49PM GMT, Sean Christopherson wrote:
> 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@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 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
>

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

Shouldn't patches 3 and 4 come before patch 2 in this series?

Thanks,
drew