On Fri, Nov 27, 2020 at 02:03:22PM +0800, Wei Li wrote:
> Armv8.3 extends the SPE by adding:
> - Alignment field in the Events packet, and filtering on this event
> using PMSEVFR_EL1.
> - Support for the Scalable Vector Extension (SVE).
>
> The main additions for SVE are:
> - Recording the vector length for SVE operations in the Operation Type
> packet. It is not possible to filter on vector length.
> - Incomplete predicate and empty predicate fields in the Events packet,
> and filtering on these events using PMSEVFR_EL1.
>
> Update the check of pmsevfr for empty/partial predicated SVE and
> alignment event in SPE driver. For adaption by the version of SPE,
> expose 'pmsver' as cap attribute to userspace.
>
> Signed-off-by: Wei Li <liwei...@huawei.com>
> ---
> v2 -> v3:
> - Make the definition of 'pmsevfr_res0' progressive and easy to check.
> (Suggested by Will.)
> ---
> v1 -> v2:
> - Rename 'pmuver' to 'pmsver', change it's type to 'u16' from 'int'.
> (Suggested by Will and Leo.)
> - Expose 'pmsver' as cap attribute through sysfs, instead of printing.
> (Suggested by Will.)
> ---
> arch/arm64/include/asm/sysreg.h | 9 ++++++++-
> drivers/perf/arm_spe_pmu.c | 21 +++++++++++++++++++--
> 2 files changed, 27 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
> index d52c1b3ce589..57e5aee6f7e6 100644
> --- a/arch/arm64/include/asm/sysreg.h
> +++ b/arch/arm64/include/asm/sysreg.h
> @@ -287,7 +287,11 @@
> #define SYS_PMSFCR_EL1_ST_SHIFT 18
>
> #define SYS_PMSEVFR_EL1 sys_reg(3, 0, 9, 9, 5)
> -#define SYS_PMSEVFR_EL1_RES0 0x0000ffff00ff0f55UL
> +#define SYS_PMSEVFR_EL1_RES0_8_2 \
> + (GENMASK_ULL(47, 32) | GENMASK_ULL(23, 16) | GENMASK_ULL(11, 8) |\
> + BIT_ULL(6) | BIT_ULL(4) | BIT_ULL(2) | BIT_ULL(0))
> +#define SYS_PMSEVFR_EL1_RES0_8_3 \
> + (SYS_PMSEVFR_EL1_RES0_8_2 & ~(BIT_ULL(18) | BIT_ULL(17) | BIT_ULL(11)))
>
> #define SYS_PMSLATFR_EL1 sys_reg(3, 0, 9, 9, 6)
> #define SYS_PMSLATFR_EL1_MINLAT_SHIFT 0
> @@ -829,6 +833,9 @@
> #define ID_AA64DFR0_PMUVER_8_5 0x6
> #define ID_AA64DFR0_PMUVER_IMP_DEF 0xf
>
> +#define ID_AA64DFR0_PMSVER_8_2 0x1
> +#define ID_AA64DFR0_PMSVER_8_3 0x2
> +
> #define ID_DFR0_PERFMON_SHIFT 24
>
> #define ID_DFR0_PERFMON_8_1 0x4
> diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c
> index cc00915ad6d1..515c51271d7f 100644
> --- a/drivers/perf/arm_spe_pmu.c
> +++ b/drivers/perf/arm_spe_pmu.c
> @@ -54,7 +54,7 @@ struct arm_spe_pmu {
> struct hlist_node hotplug_node;
>
> int irq; /* PPI */
> -
> + u16 pmsver;
> u16 min_period;
> u16 counter_sz;
>
> @@ -93,6 +93,7 @@ enum arm_spe_pmu_capabilities {
> SPE_PMU_CAP_FEAT_MAX,
> SPE_PMU_CAP_CNT_SZ = SPE_PMU_CAP_FEAT_MAX,
> SPE_PMU_CAP_MIN_IVAL,
> + SPE_PMU_CAP_PMSVER,
> };
>
> static int arm_spe_pmu_feat_caps[SPE_PMU_CAP_FEAT_MAX] = {
> @@ -110,6 +111,8 @@ static u32 arm_spe_pmu_cap_get(struct arm_spe_pmu
> *spe_pmu, int cap)
> return spe_pmu->counter_sz;
> case SPE_PMU_CAP_MIN_IVAL:
> return spe_pmu->min_period;
> + case SPE_PMU_CAP_PMSVER:
> + return spe_pmu->pmsver;
> default:
> WARN(1, "unknown cap %d\n", cap);
> }
> @@ -143,6 +146,7 @@ static struct attribute *arm_spe_pmu_cap_attr[] = {
> SPE_CAP_EXT_ATTR_ENTRY(ernd, SPE_PMU_CAP_ERND),
> SPE_CAP_EXT_ATTR_ENTRY(count_size, SPE_PMU_CAP_CNT_SZ),
> SPE_CAP_EXT_ATTR_ENTRY(min_interval, SPE_PMU_CAP_MIN_IVAL),
> + SPE_CAP_EXT_ATTR_ENTRY(pmsver, SPE_PMU_CAP_PMSVER),
> NULL,
> };
>
> @@ -655,6 +659,18 @@ static irqreturn_t arm_spe_pmu_irq_handler(int irq, void
> *dev)
> return IRQ_HANDLED;
> }
>
> +static u64 arm_spe_pmsevfr_res0(u16 pmsver)
> +{
> + switch (pmsver) {
> + case ID_AA64DFR0_PMSVER_8_2:
> + return SYS_PMSEVFR_EL1_RES0_8_2;
> + case ID_AA64DFR0_PMSVER_8_3:
> + return SYS_PMSEVFR_EL1_RES0_8_3;
> + default:
> + return -1;
> + }
I don't think -1 is the right choice here if we don't recognise the
version, as it means that old kernels won't work on new hardware. I think
it would be better to return the highest architecture version we know about
in that case...
> +}
> +
> /* Perf callbacks */
> static int arm_spe_pmu_event_init(struct perf_event *event)
> {
> @@ -670,7 +686,7 @@ static int arm_spe_pmu_event_init(struct perf_event
> *event)
> !cpumask_test_cpu(event->cpu, &spe_pmu->supported_cpus))
> return -ENOENT;
>
> - if (arm_spe_event_to_pmsevfr(event) & SYS_PMSEVFR_EL1_RES0)
> + if (arm_spe_event_to_pmsevfr(event) &
> arm_spe_pmsevfr_res0(spe_pmu->pmsver))
> return -EOPNOTSUPP;
>
> if (attr->exclude_idle)
> @@ -937,6 +953,7 @@ static void __arm_spe_pmu_dev_probe(void *info)
> fld, smp_processor_id());
> return;
> }
> + spe_pmu->pmsver = (u16)fld;
... which also means we should clamp this value now that we expose it to
userspace. Otherwise, userspace can't rely on this field for anything.
That said -- please can you tell me what userspace intends to do with
this version number?
Will
