> -----Original Message-----
> From: Linuxarm [mailto:linuxarm-boun...@huawei.com] On Behalf Of
> Shameerali Kolothum Thodi
> Sent: 18 October 2018 14:34
> To: Robin Murphy <robin.mur...@arm.com>; lorenzo.pieral...@arm.com;
> jean-philippe.bruc...@arm.com
> Cc: mark.rutl...@arm.com; vkil...@codeaurora.org;
> neil.m.lee...@gmail.com; pa...@codeaurora.org; will.dea...@arm.com;
> rruig...@codeaurora.org; Linuxarm <linux...@huawei.com>; linux-
> ker...@vger.kernel.org; linux-a...@vger.kernel.org; linux-arm-
> ker...@lists.infradead.org
> Subject: RE: [PATCH v4 4/4] perf/smmuv3_pmu: Enable HiSilicon Erratum
> 162001800 quirk
>
> Hi Robin,
>
> > -----Original Message-----
> > From: Robin Murphy [mailto:robin.mur...@arm.com]
> > Sent: 18 October 2018 12:44
> > To: Shameerali Kolothum Thodi <shameerali.kolothum.th...@huawei.com>;
> > lorenzo.pieral...@arm.com; jean-philippe.bruc...@arm.com
> > Cc: will.dea...@arm.com; mark.rutl...@arm.com; Guohanjun (Hanjun Guo)
> > <guohan...@huawei.com>; John Garry <john.ga...@huawei.com>;
> > pa...@codeaurora.org; vkil...@codeaurora.org; rruig...@codeaurora.org;
> > linux-a...@vger.kernel.org; linux-kernel@vger.kernel.org; linux-arm-
> > ker...@lists.infradead.org; Linuxarm <linux...@huawei.com>;
> > neil.m.lee...@gmail.com
> > Subject: Re: [PATCH v4 4/4] perf/smmuv3_pmu: Enable HiSilicon Erratum
> > 162001800 quirk
[...]
> > > +static const struct smmu_pmu_erratum_wa smmu_pmu_wa[] = {
> > > + {
> > > + .match_type = se_match_acpi_oem,
> > > + .id = hisi_162001800_oem_info,
> > > + .desc_str = "HiSilicon erratum 162001800",
> > > + .enable = hisi_erratum_evcntr_rdonly,
> > > + },
> > > +};
> > > +
> >
> > There's an awful lot of raw ACPI internals splashed about here -
> > couldn't at least some of it be abstracted behind the IORT code? In
> > fact, can't IORT just set all this stuff up in advance like it does for
> > SMMUs?
>
> Hmmm.. Sorry, not clear to me. You mean to say associate the IORT node
> with platform device and retrieve it in driver just like smmu does for
> "model" checks? Not sure that works here if that’s what the above meant.
>
> > > #define to_smmu_pmu(p) (container_of(p, struct smmu_pmu, pmu))
> > >
> > > #define SMMU_PMU_EVENT_ATTR_EXTRACTOR(_name, _config, _start,
> > _end) \
> > > @@ -224,15 +271,20 @@ 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_PMU_OPT_EVCNTR_RDONLY) {
> > > + new = smmu_pmu_counter_get_value(smmu_pmu, idx);
> >
> > Something's clearly missing, because if this happens to start at 0, the
> > current overflow handling code cannot possibly give the correct count.
> > Much as I hate the reset-to-half-period idiom for being impossible to
> > make sense of, it does make various aspects appear a lot simpler than
> > they really are. Wait, maybe that's yet another reason to hate it...
>
> Yes, if the counter starts at 0 and overflow happens, it won't possibly give
> the correct count compared to the reset-to-half-period logic. Since this is a
> 64 bit counter, just hope that, it won't necessarily happen that often.
[...]
> > > +static void smmu_pmu_enable_errata(struct smmu_pmu *smmu_pmu,
> > > + enum smmu_pmu_erratum_match_type type,
> > > + se_match_fn_t match_fn,
> > > + void *arg)
> > > +{
> > > + const struct smmu_pmu_erratum_wa *wa = smmu_pmu_wa;
> > > +
> > > + for (; wa->desc_str; wa++) {
> > > + if (wa->match_type != type)
> > > + continue;
> > > +
> > > + if (match_fn(wa, arg)) {
> > > + if (wa->enable) {
> > > + wa->enable(smmu_pmu);
> > > + dev_info(smmu_pmu->dev,
> > > + "Enabling workaround for %s\n",
> > > + wa->desc_str);
> > > + }
> >
> > Just how many kinds of broken are we expecting here? Is this lifted from
> > the arm64 cpufeature framework, because it seems like absolute overkill
> > for a simple PMU driver which in all reality is only ever going to
> > wiggle a few flags in some data structure.
>
> Yes, this erratum framework is based on the arm_arch_timer code. Agree that
> this is an overkill if it is just to support this hardware. I am not sure
> this can be
> extended to add the IMPLEMENTATION DEFINED events in future(I haven't
> looked into that now). If this is not that useful in the near future, I will
> remove
> the
> framework part and use the OEM info directly to set the flag. Please let me
> know
> your thoughts..
Below is another take on this patch. Please let me know if this makes any
sense..
Thanks,
Shameer
----8----
diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c
index ef94b90..6f81b94 100644
--- a/drivers/perf/arm_smmuv3_pmu.c
+++ b/drivers/perf/arm_smmuv3_pmu.c
@@ -96,6 +96,8 @@
#define SMMU_PA_SHIFT 12
+#define SMMU_PMU_OPT_EVCNTR_RDONLY (1 << 0)
+
static int cpuhp_state_num;
struct smmu_pmu {
@@ -111,10 +113,38 @@ struct smmu_pmu {
struct device *dev;
void __iomem *reg_base;
void __iomem *reloc_base;
+ u32 options;
u64 counter_present_mask;
u64 counter_mask;
};
+struct erratum_acpi_oem_info {
+ char oem_id[ACPI_OEM_ID_SIZE + 1];
+ char oem_table_id[ACPI_OEM_TABLE_ID_SIZE + 1];
+ u32 oem_revision;
+ void (*enable)(struct smmu_pmu *smmu_pmu);
+};
+
+void hisi_erratum_evcntr_rdonly(struct smmu_pmu *smmu_pmu)
+{
+ smmu_pmu->options |= SMMU_PMU_OPT_EVCNTR_RDONLY;
+ dev_info(smmu_pmu->dev, "Enabling HiSilicon erratum 162001800\n");
+}
+
+static struct erratum_acpi_oem_info acpi_oem_info[] = {
+ /*
+ * Note that trailing spaces are required to properly match
+ * the OEM table information.
+ */
+ {
+ .oem_id = "HISI ",
+ .oem_table_id = "HIP08 ",
+ .oem_revision = 0,
+ .enable = hisi_erratum_evcntr_rdonly,
+ },
+ { /* Sentinel indicating the end of the OEM array */ },
+};
+
#define to_smmu_pmu(p) (container_of(p, struct smmu_pmu, pmu))
#define SMMU_PMU_EVENT_ATTR_EXTRACTOR(_name, _config, _start, _end) \
@@ -224,15 +254,20 @@ 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_PMU_OPT_EVCNTR_RDONLY) {
+ 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_get_event_filter(struct perf_event *event, u32 *span,
@@ -670,6 +705,28 @@ static void smmu_pmu_reset(struct smmu_pmu *smmu_pmu)
smmu_pmu->reloc_base + SMMU_PMCG_OVSCLR0);
}
+static void smmu_pmu_check_acpi_workarounds(struct smmu_pmu *smmu_pmu)
+{
+ static const struct erratum_acpi_oem_info empty_oem_info = {};
+ const struct erratum_acpi_oem_info *info = acpi_oem_info;
+ struct acpi_table_header *hdr;
+
+ if (ACPI_FAILURE(acpi_get_table(ACPI_SIG_IORT, 0, &hdr))) {
+ dev_err(smmu_pmu->dev, "failed to get IORT\n");
+ return;
+ }
+
+ /* Iterate over the ACPI OEM info array, looking for a match */
+ while (memcmp(info, &empty_oem_info, sizeof(*info))) {
+ if (!memcmp(info->oem_id, hdr->oem_id, ACPI_OEM_ID_SIZE) &&
+ !memcmp(info->oem_table_id, hdr->oem_table_id,
ACPI_OEM_TABLE_ID_SIZE) &&
+ info->oem_revision == hdr->oem_revision)
+ info->enable(smmu_pmu);
+
+ info++;
+ }
+}
+
static int smmu_pmu_probe(struct platform_device *pdev)
{
struct smmu_pmu *smmu_pmu;
@@ -749,6 +806,8 @@ static int smmu_pmu_probe(struct platform_device *pdev)
return -EINVAL;
}
+ smmu_pmu_check_acpi_workarounds(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)));
