On Thu, Feb 26, 2026 at 08:32:34AM +0000, Jiakai Xu wrote:
> Add RISC-V KVM selftests to verify the SBI Steal-Time Accounting (STA)
> shared memory alignment requirements.
>
> The SBI specification requires the STA shared memory GPA to be 64-byte
> aligned, or set to all-ones to explicitly disable steal-time accounting.
> This test verifies that KVM enforces the expected behavior when
> configuring the SBI STA shared memory via KVM_SET_ONE_REG.
>
> Specifically, the test checks that:
> - misaligned GPAs are rejected with -EINVAL
> - 64-byte aligned GPAs are accepted
> - all-ones GPA is accepted
>
> Signed-off-by: Jiakai Xu <[email protected]>
> Signed-off-by: Jiakai Xu <[email protected]>
> ---
> V7 -> V8: Moved INVALID_GPA definition to kvm_util_types.h.
> Removed comments in RISC-V check_steal_time_uapi().
> Corrected reg.id assignment for SBI STA.
> V6 -> V7: Removed RISCV_SBI_STA_REG() macro addition and used existing
> KVM_REG_RISCV_SBI_STA_REG(shmem_lo) instead.
> Refined assertion messages per review feedback.
> Split into two patches per Andrew Jones' suggestion:
> Refactored UAPI tests from steal_time_init() into dedicated
> check_steal_time_uapi() function and added empty stub for
> RISC-V.
> Filled in RISC-V stub with STA alignment tests. (this patch)
> ---
> .../selftests/kvm/include/kvm_util_types.h | 4 +++
> tools/testing/selftests/kvm/steal_time.c | 25 +++++++++++++++++++
> 2 files changed, 29 insertions(+)
>
> diff --git a/tools/testing/selftests/kvm/include/kvm_util_types.h
> b/tools/testing/selftests/kvm/include/kvm_util_types.h
> index ec787b97cf184..90567f8243fe9 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util_types.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util_types.h
> @@ -17,4 +17,8 @@
> typedef uint64_t vm_paddr_t; /* Virtual Machine (Guest) physical address */
> typedef uint64_t vm_vaddr_t; /* Virtual Machine (Guest) virtual address */
>
> +#if defined(__riscv)
Why this #if ? INVALID_GPA is common to all architectures (see
include/linux/kvm_types.h). That's why I suggested putting it in this
shared header.
> +#define INVALID_GPA (~(uint64_t)0)
> +#endif
> +
> #endif /* SELFTEST_KVM_UTIL_TYPES_H */
> diff --git a/tools/testing/selftests/kvm/steal_time.c
> b/tools/testing/selftests/kvm/steal_time.c
> index 6f77df4deaad3..e90aad9561ff7 100644
> --- a/tools/testing/selftests/kvm/steal_time.c
> +++ b/tools/testing/selftests/kvm/steal_time.c
> @@ -324,6 +324,31 @@ static void steal_time_dump(struct kvm_vm *vm, uint32_t
> vcpu_idx)
>
> static void check_steal_time_uapi(struct kvm_vcpu *vcpu)
> {
> + struct kvm_one_reg reg;
> + uint64_t shmem;
> + int ret;
> +
> + reg.id = KVM_REG_RISCV |
> + KVM_REG_SIZE_ULONG |
> + KVM_REG_RISCV_SBI_STATE |
> + KVM_REG_RISCV_SBI_STA |
> + KVM_REG_RISCV_SBI_STA_REG(shmem_lo);
> + reg.addr = (uint64_t)&shmem;
> +
> + shmem = ST_GPA_BASE + 1;
> + ret = __vcpu_ioctl(vcpu, KVM_SET_ONE_REG, ®);
> + TEST_ASSERT(ret == -1 && errno == EINVAL,
> + "misaligned STA shmem returns -EINVAL");
> +
> + shmem = ST_GPA_BASE;
> + ret = __vcpu_ioctl(vcpu, KVM_SET_ONE_REG, ®);
> + TEST_ASSERT(ret == 0,
> + "aligned STA shmem succeeds");
> +
> + shmem = INVALID_GPA;
> + ret = __vcpu_ioctl(vcpu, KVM_SET_ONE_REG, ®);
> + TEST_ASSERT(ret == 0,
> + "all-ones for STA shmem succeeds");
> }
>
> #endif
> --
> 2.34.1
>
Thanks,
drew
