On Fri, 12 Sep 2025 09:27:40 +0100,
Itaru Kitayama <itaru.kitayama@xxxxxxxxx> wrote:
>
> Signed-off-by: Itaru Kitayama <itaru.kitayama@xxxxxxxxxxx>
This isn't an acceptable commit message.
> ---
> Seen a build failure with old Ubuntu 22.04 LTS, while the latest release
> has no build issue, a write to the bit fields is RAZ/WI, remove the
> function.
> ---
> tools/testing/selftests/kvm/arm64/vpmu_counter_access.c | 6 ------
> 1 file changed, 6 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c b/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c
> index f16b3b27e32ed7ca57481f27d689d47783aa0345..56214a4430be90b3e1d840f2719b22dd44f0b49b 100644
> --- a/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c
> +++ b/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c
> @@ -45,11 +45,6 @@ static uint64_t get_pmcr_n(uint64_t pmcr)
> return FIELD_GET(ARMV8_PMU_PMCR_N, pmcr);
> }
>
> -static void set_pmcr_n(uint64_t *pmcr, uint64_t pmcr_n)
> -{
> - u64p_replace_bits((__u64 *) pmcr, pmcr_n, ARMV8_PMU_PMCR_N);
> -}
> -
> static uint64_t get_counters_mask(uint64_t n)
> {
> uint64_t mask = BIT(ARMV8_PMU_CYCLE_IDX);
> @@ -490,7 +485,6 @@ static void test_create_vpmu_vm_with_pmcr_n(uint64_t pmcr_n, bool expect_fail)
> * Setting a larger value of PMCR.N should not modify the field, and
> * return a success.
> */
> - set_pmcr_n(&pmcr, pmcr_n);
> vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_PMCR_EL0), pmcr);
> pmcr = vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_PMCR_EL0));
>
>
So what are you fixing here? A build failure? A semantic defect?
Something else? What makes this a valid change?
Frankly, I have no idea.
But KVM definitely allows PMCR_EL0.N to be written from userspace, and
that's not going to change.
M.
--
Without deviation from the norm, progress is not possible.
