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SubjectRe: [PATCH v6 4/4] perf/smmuv3_pmu: Enable HiSilicon Erratum 162001800 quirk
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On 04/02/2019 12:13, Shameer Kolothum wrote:
> HiSilicon erratum 162001800 describes the limitation of
> SMMUv3 PMCG implementation on HiSilicon Hip08 platforms.
>
> On these platforms, the PMCG event counter registers
> (SMMU_PMCG_EVCNTRn) are read only and as a result it
> is not possible to set the initial counter period value
> on event monitor start.
>
> To work around this, the current value of the counter
> is read and used for delta calculations. OEM information
> from ACPI header is used to identify the affected hardware
> platforms.
>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> ---
> drivers/acpi/arm64/iort.c | 16 ++++++++++++++-
> drivers/perf/arm_smmuv3_pmu.c | 48 ++++++++++++++++++++++++++++++++++++-------
> include/linux/acpi_iort.h | 1 +
> 3 files changed, 57 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index e2c9b26..4dc68de 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -1366,9 +1366,23 @@ static void __init arm_smmu_v3_pmcg_init_resources(struct resource *res,
> ACPI_EDGE_SENSITIVE, &res[2]);
> }
>
> +static struct acpi_platform_list pmcg_plat_info[] __initdata = {
> + /* HiSilicon Hip08 Platform */
> + {"HISI ", "HIP08 ", 0, ACPI_SIG_IORT, greater_than_or_equal, 0,
> + IORT_SMMU_V3_PMCG_HISI_HIP08},
> + { }
> +};
> +
> static int __init arm_smmu_v3_pmcg_add_platdata(struct platform_device *pdev)
> {
> - u32 model = IORT_SMMU_V3_PMCG_GENERIC;
> + u32 model;
> + int idx;
> +
> + idx = acpi_match_platform_list(pmcg_plat_info);
> + if (idx >= 0)
> + model = pmcg_plat_info[idx].data;
> + else
> + model = IORT_SMMU_V3_PMCG_GENERIC;
>
> return platform_device_add_data(pdev, &model, sizeof(model));
> }
> diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c
> index eeb9dee..95a3ed0 100644
> --- a/drivers/perf/arm_smmuv3_pmu.c
> +++ b/drivers/perf/arm_smmuv3_pmu.c
> @@ -35,6 +35,7 @@
> */
>
> #include <linux/acpi.h>
> +#include <linux/acpi_iort.h>
> #include <linux/bitfield.h>
> #include <linux/bitops.h>
> #include <linux/cpuhotplug.h>
> @@ -93,6 +94,8 @@
>
> #define SMMU_PMCG_PA_SHIFT 12
>
> +#define SMMU_PMCG_EVCNTR_RDONLY BIT(0)
> +
> static int cpuhp_state_num;
>
> struct smmu_pmu {
> @@ -107,6 +110,7 @@ struct smmu_pmu {
> struct device *dev;
> void __iomem *reg_base;
> void __iomem *reloc_base;
> + u32 options;

Super-nit: can we put options the other side of counter_mask so as to
not waste 8 whole bytes on padding? ;)

Otherwise, nothing stands out to my eye, so

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

Cheers,
Robin.

> u64 counter_mask;
> bool global_filter;
> u32 global_filter_span;
> @@ -222,15 +226,27 @@ static void smmu_pmu_set_period(struct smmu_pmu *smmu_pmu,
> u32 idx = hwc->idx;
> u64 new;
>
> - /*
> - * We limit the max period to half the max counter value of the counter
> - * size, so that even in the case of extreme interrupt latency the
> - * counter will (hopefully) not wrap past its initial value.
> - */
> - new = smmu_pmu->counter_mask >> 1;
> + if (smmu_pmu->options & SMMU_PMCG_EVCNTR_RDONLY) {
> + /*
> + * On platforms that require this quirk, if the counter starts
> + * at < half_counter value and wraps, the current logic of
> + * handling the overflow may not work. It is expected that,
> + * those platforms will have full 64 counter bits implemented
> + * so that such a possibility is remote(eg: HiSilicon HIP08).
> + */
> + new = smmu_pmu_counter_get_value(smmu_pmu, idx);
> + } else {
> + /*
> + * We limit the max period to half the max counter value
> + * of the counter size, so that even in the case of extreme
> + * interrupt latency the counter will (hopefully) not wrap
> + * past its initial value.
> + */
> + new = smmu_pmu->counter_mask >> 1;
> + smmu_pmu_counter_set_value(smmu_pmu, idx, new);
> + }
>
> local64_set(&hwc->prev_count, new);
> - smmu_pmu_counter_set_value(smmu_pmu, idx, new);
> }
>
> static void smmu_pmu_set_event_filter(struct perf_event *event,
> @@ -674,6 +690,22 @@ static void smmu_pmu_reset(struct smmu_pmu *smmu_pmu)
> smmu_pmu->reloc_base + SMMU_PMCG_OVSCLR0);
> }
>
> +static void smmu_pmu_get_acpi_options(struct smmu_pmu *smmu_pmu)
> +{
> + u32 model;
> +
> + model = *(u32 *)dev_get_platdata(smmu_pmu->dev);
> +
> + switch (model) {
> + case IORT_SMMU_V3_PMCG_HISI_HIP08:
> + /* HiSilicon Erratum 162001800 */
> + smmu_pmu->options |= SMMU_PMCG_EVCNTR_RDONLY;
> + break;
> + }
> +
> + dev_notice(smmu_pmu->dev, "option mask 0x%x\n", smmu_pmu->options);
> +}
> +
> static int smmu_pmu_probe(struct platform_device *pdev)
> {
> struct smmu_pmu *smmu_pmu;
> @@ -752,6 +784,8 @@ static int smmu_pmu_probe(struct platform_device *pdev)
> return -EINVAL;
> }
>
> + smmu_pmu_get_acpi_options(smmu_pmu);
> +
> /* Pick one CPU to be the preferred one to use */
> smmu_pmu->on_cpu = get_cpu();
> WARN_ON(irq_set_affinity(smmu_pmu->irq, cpumask_of(smmu_pmu->on_cpu)));
> diff --git a/include/linux/acpi_iort.h b/include/linux/acpi_iort.h
> index 832bd6a..bdb6912 100644
> --- a/include/linux/acpi_iort.h
> +++ b/include/linux/acpi_iort.h
> @@ -31,6 +31,7 @@
> * that, this is not part of the IORT specification.
> */
> #define IORT_SMMU_V3_PMCG_GENERIC 0x00000000 /* Generic SMMUv3 PMCG */
> +#define IORT_SMMU_V3_PMCG_HISI_HIP08 0x00000001 /* HiSilicon HIP08 PMCG */
>
> int iort_register_domain_token(int trans_id, phys_addr_t base,
> struct fwnode_handle *fw_node);
>

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