Re: [PATCH] KVM: LoongArch: selftests: Add steal time test case

[Huacai Chen]

On Mon, Feb 2, 2026 at 10:03 AM Bibo Mao <maobibo@xxxxxxxxxxx> wrote:
>
> Hi Huacai,
>
> On 2026/1/31 下午9:47, Huacai Chen wrote:
> > Since paravirt preempt is also applied, I applied this one with some
> > modifications, you can check whether it is correct.
> >
> > https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson.git/commit/?h=loongarch-kvm&id=cf991b57ffc808d69cb1f911563b1d4658774ccf
>
> I checked the pendning patches in loongarch-kvm branch, they all look
> good to me.
OK, then are there any updates on this one?
https://lore.kernel.org/loongarch/CAAhV-H57b14qY+5jqe+Fd5FTQq6jrhurfNBCqBqwG6SUpKFhTw@xxxxxxxxxxxxxx/T/#t

Huacai
>
> Thanks for doing this.
>
> Regards
> Bibo Mao
> >
> > Huacai
> >
> > On Thu, Jan 29, 2026 at 10:18 AM Bibo Mao <maobibo@xxxxxxxxxxx> wrote:
> >>
> >> LoongArch KVM supports steal time accounting now, here add steal time
> >> test case on LoongArch.
> >>
> >> Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
> >> ---
> >>   tools/testing/selftests/kvm/Makefile.kvm |  1 +
> >>   tools/testing/selftests/kvm/steal_time.c | 85 ++++++++++++++++++++++++
> >>   2 files changed, 86 insertions(+)
> >>
> >> diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
> >> index ba5c2b643efa..a18c00f1a4fa 100644
> >> --- a/tools/testing/selftests/kvm/Makefile.kvm
> >> +++ b/tools/testing/selftests/kvm/Makefile.kvm
> >> @@ -228,6 +228,7 @@ TEST_GEN_PROGS_loongarch += kvm_page_table_test
> >>   TEST_GEN_PROGS_loongarch += memslot_modification_stress_test
> >>   TEST_GEN_PROGS_loongarch += memslot_perf_test
> >>   TEST_GEN_PROGS_loongarch += set_memory_region_test
> >> +TEST_GEN_PROGS_loongarch += steal_time
> >>
> >>   SPLIT_TESTS += arch_timer
> >>   SPLIT_TESTS += get-reg-list
> >> diff --git a/tools/testing/selftests/kvm/steal_time.c b/tools/testing/selftests/kvm/steal_time.c
> >> index 8edc1fca345b..ee13e8973c45 100644
> >> --- a/tools/testing/selftests/kvm/steal_time.c
> >> +++ b/tools/testing/selftests/kvm/steal_time.c
> >> @@ -301,6 +301,91 @@ static void steal_time_dump(struct kvm_vm *vm, uint32_t vcpu_idx)
> >>          pr_info("\n");
> >>   }
> >>
> >> +#elif defined(__loongarch__)
> >> +/* steal_time must have 64-byte alignment */
> >> +#define STEAL_TIME_SIZE                ((sizeof(struct kvm_steal_time) + 63) & ~63)
> >> +#define KVM_STEAL_PHYS_VALID   BIT_ULL(0)
> >> +
> >> +struct kvm_steal_time {
> >> +       __u64 steal;
> >> +       __u32 version;
> >> +       __u32 flags;
> >> +       __u32 pad[12];
> >> +};
> >> +
> >> +static bool is_steal_time_supported(struct kvm_vcpu *vcpu)
> >> +{
> >> +       int err;
> >> +       uint64_t val;
> >> +       struct kvm_device_attr attr = {
> >> +               .group = KVM_LOONGARCH_VCPU_CPUCFG,
> >> +               .attr = CPUCFG_KVM_FEATURE,
> >> +               .addr = (uint64_t)&val,
> >> +       };
> >> +
> >> +       err = __vcpu_ioctl(vcpu, KVM_HAS_DEVICE_ATTR, &attr);
> >> +       if (err)
> >> +               return false;
> >> +
> >> +       err = __vcpu_ioctl(vcpu, KVM_GET_DEVICE_ATTR, &attr);
> >> +       if (err)
> >> +               return false;
> >> +
> >> +       return val & BIT(KVM_FEATURE_STEAL_TIME);
> >> +}
> >> +
> >> +static void steal_time_init(struct kvm_vcpu *vcpu, uint32_t i)
> >> +{
> >> +       struct kvm_vm *vm = vcpu->vm;
> >> +       uint64_t st_gpa;
> >> +       int err;
> >> +       struct kvm_device_attr attr = {
> >> +               .group = KVM_LOONGARCH_VCPU_PVTIME_CTRL,
> >> +               .attr = KVM_LOONGARCH_VCPU_PVTIME_GPA,
> >> +               .addr = (uint64_t)&st_gpa,
> >> +       };
> >> +
> >> +       /* ST_GPA_BASE is identity mapped */
> >> +       st_gva[i] = (void *)(ST_GPA_BASE + i * STEAL_TIME_SIZE);
> >> +       sync_global_to_guest(vm, st_gva[i]);
> >> +
> >> +       err = __vcpu_ioctl(vcpu, KVM_HAS_DEVICE_ATTR, &attr);
> >> +       TEST_ASSERT(err == 0, "No PV stealtime Feature");
> >> +
> >> +       st_gpa = (unsigned long)st_gva[i] | KVM_STEAL_PHYS_VALID;
> >> +       err = __vcpu_ioctl(vcpu, KVM_SET_DEVICE_ATTR, &attr);
> >> +       TEST_ASSERT(err == 0, "Fail to set PV stealtime GPA");
> >> +}
> >> +
> >> +static void guest_code(int cpu)
> >> +{
> >> +       struct kvm_steal_time *st = st_gva[cpu];
> >> +       uint32_t version;
> >> +
> >> +       memset(st, 0, sizeof(*st));
> >> +       GUEST_SYNC(0);
> >> +
> >> +       GUEST_ASSERT(!(READ_ONCE(st->version) & 1));
> >> +       WRITE_ONCE(guest_stolen_time[cpu], st->steal);
> >> +       version = READ_ONCE(st->version);
> >> +       GUEST_ASSERT(!(READ_ONCE(st->version) & 1));
> >> +       GUEST_SYNC(1);
> >> +
> >> +       GUEST_ASSERT(!(READ_ONCE(st->version) & 1));
> >> +       GUEST_ASSERT(version < READ_ONCE(st->version));
> >> +       WRITE_ONCE(guest_stolen_time[cpu], st->steal);
> >> +       GUEST_ASSERT(!(READ_ONCE(st->version) & 1));
> >> +       GUEST_DONE();
> >> +}
> >> +
> >> +static void steal_time_dump(struct kvm_vm *vm, uint32_t vcpu_idx)
> >> +{
> >> +       struct kvm_steal_time *st = addr_gva2hva(vm, (ulong)st_gva[vcpu_idx]);
> >> +
> >> +       ksft_print_msg("VCPU%d:\n", vcpu_idx);
> >> +       ksft_print_msg("    steal:     %lld\n", st->steal);
> >> +       ksft_print_msg("    version:   %d\n", st->version);
> >> +}
> >>   #endif
> >>
> >>   static void *do_steal_time(void *arg)
> >>
> >> base-commit: 8dfce8991b95d8625d0a1d2896e42f93b9d7f68d
> >> --
> >> 2.39.3
> >>
>
>