Re: [PATCH v8 9/9] perf/amd/iommu: Enable support for multiple IOMMUs

Borislav Petkov
2017-01-22T19:55:46Z

On Mon, Jan 16, 2017 at 01:23:36AM -0600, Suravee Suthikulpanit wrote:
> From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
>
> Add multi-IOMMU support for perf by exposing an AMD IOMMU PMU
> for each IOMMU found in the system via:
>
> /bus/event_source/devices/amd_iommu_x
>
> where x is the IOMMU index. This allows users to specify
> different events to be programed onto performance counters

"programmed"

Please introduce a spellchecker into your patch creation workflow.

> of each IOMMU.
>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Borislav Petkov <bp@alien8.de>
> Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
> ---
> arch/x86/events/amd/iommu.c | 114 ++++++++++++++++++++++++++------------------
> 1 file changed, 67 insertions(+), 47 deletions(-)
>
> diff --git a/arch/x86/events/amd/iommu.c b/arch/x86/events/amd/iommu.c
> index 223c01d..38eafbf 100644
> --- a/arch/x86/events/amd/iommu.c
> +++ b/arch/x86/events/amd/iommu.c
> @@ -35,16 +35,21 @@
> #define _GET_PASID_MASK(ev) ((ev->hw.extra_reg.config >> 16) & 0xFFFFULL)
> #define _GET_DOMID_MASK(ev) ((ev->hw.extra_reg.config >> 32) & 0xFFFFULL)
>
> -static struct perf_amd_iommu __perf_iommu;
> +#define PERF_AMD_IOMMU_NAME_SZ 16

AMD_IOMMU_PMU_NAME_SIZE

sounds more to the point to me.

> struct perf_amd_iommu {
> + struct list_head list;
> struct pmu pmu;
> + unsigned int idx;
> + char name[PERF_AMD_IOMMU_NAME_SZ];
> u8 max_banks;
> u8 max_counters;
> u64 cntr_assign_mask;
> raw_spinlock_t lock;
> };

...

> @@ -253,30 +248,34 @@ static void perf_iommu_enable_event(struct perf_event *ev)
> u64 reg = 0ULL;
>
> reg = csource;
> - amd_iommu_pc_set_reg(0, bank, cntr,
> + amd_iommu_pc_set_reg(hwc->idx, bank, cntr,
> IOMMU_PC_COUNTER_SRC_REG, &reg);
>
> reg = devid | (_GET_DEVID_MASK(ev) << 32);
> if (reg)
> reg |= BIT(31);
> - amd_iommu_pc_set_reg(0, bank, cntr, IOMMU_PC_DEVID_MATCH_REG, &reg);
> + amd_iommu_pc_set_reg(hwc->idx, bank, cntr,
> + IOMMU_PC_DEVID_MATCH_REG, &reg);
>
> reg = _GET_PASID(ev) | (_GET_PASID_MASK(ev) << 32);
> if (reg)
> reg |= BIT(31);
> - amd_iommu_pc_set_reg(0, bank, cntr, IOMMU_PC_PASID_MATCH_REG, &reg);
> + amd_iommu_pc_set_reg(hwc->idx, bank, cntr,
> + IOMMU_PC_PASID_MATCH_REG, &reg);
>
> reg = _GET_DOMID(ev) | (_GET_DOMID_MASK(ev) << 32);
> if (reg)
> reg |= BIT(31);
> - amd_iommu_pc_set_reg(0, bank, cntr, IOMMU_PC_DOMID_MATCH_REG, &reg);
> + amd_iommu_pc_set_reg(hwc->idx, bank, cntr,
> + IOMMU_PC_DOMID_MATCH_REG, &reg);

You can let those stick out - the 80 cols rule is not a strict one:

reg = csource;
amd_iommu_pc_set_reg(hwc->idx, bank, cntr, IOMMU_PC_COUNTER_SRC_REG, &reg);

reg = devid | (_GET_DEVID_MASK(ev) << 32);
if (reg)
reg |= BIT(31);
amd_iommu_pc_set_reg(hwc->idx, bank, cntr, IOMMU_PC_DEVID_MATCH_REG, &reg);

reg = _GET_PASID(ev) | (_GET_PASID_MASK(ev) << 32);
if (reg)
reg |= BIT(31);
amd_iommu_pc_set_reg(hwc->idx, bank, cntr, IOMMU_PC_PASID_MATCH_REG, &reg);

reg = _GET_DOMID(ev) | (_GET_DOMID_MASK(ev) << 32);
if (reg)
reg |= BIT(31);
amd_iommu_pc_set_reg(hwc->idx, bank, cntr, IOMMU_PC_DOMID_MATCH_REG, &reg);
}

> static void perf_iommu_disable_event(struct perf_event *event)
> {
> + struct hw_perf_event *hwc = &event->hw;
> u64 reg = 0ULL;
>
> - amd_iommu_pc_set_reg(0, _GET_BANK(event), _GET_CNTR(event),
> + amd_iommu_pc_set_reg(hwc->idx, _GET_BANK(event), _GET_CNTR(event),
> IOMMU_PC_COUNTER_SRC_REG, &reg);
> }
>
> @@ -295,7 +294,7 @@ static void perf_iommu_start(struct perf_event *event, int flags)
> return;
>
> val = local64_read(&hwc->prev_count) & GENMASK_ULL(48, 0);
> - if (amd_iommu_pc_set_reg(0, _GET_BANK(event), _GET_CNTR(event),
> + if (amd_iommu_pc_set_reg(hwc->idx, _GET_BANK(event), _GET_CNTR(event),
> IOMMU_PC_COUNTER_REG, &val))
> return;
>
> @@ -309,7 +308,7 @@ static void perf_iommu_read(struct perf_event *event)
> s64 delta;
> struct hw_perf_event *hwc = &event->hw;
>
> - if (amd_iommu_pc_get_reg(0, _GET_BANK(event), _GET_CNTR(event),
> + if (amd_iommu_pc_get_reg(hwc->idx, _GET_BANK(event), _GET_CNTR(event),
> IOMMU_PC_COUNTER_REG, &count))
> return;
>
> @@ -407,6 +406,13 @@ static __init int _init_events_attrs(void)
>
> static __init void amd_iommu_pc_exit(void)
> {
> + struct perf_amd_iommu *pi, *next;
> +
> + list_for_each_entry_safe(pi, next, &perf_amd_iommu_list, list) {
> + list_del(&pi->list);
> + kfree(pi);
> + }
> +
> if (amd_iommu_events_group.attrs) {
> kfree(amd_iommu_events_group.attrs);
> amd_iommu_events_group.attrs = NULL;
> @@ -421,46 +427,46 @@ static __init void amd_iommu_pc_exit(void)
> };
>
> static __init int
> -_init_perf_amd_iommu(struct perf_amd_iommu *perf_iommu, char *name)
> +init_one_perf_amd_iommu(struct perf_amd_iommu *perf_iommu, unsigned int idx)
> {
> int ret;
>
> raw_spin_lock_init(&perf_iommu->lock);
>
> - /* Init cpumask attributes to only core 0 */
> - cpumask_set_cpu(0, &iommu_cpumask);
> -
> - perf_iommu->max_banks = amd_iommu_pc_get_max_banks(0);
> - perf_iommu->max_counters = amd_iommu_pc_get_max_counters(0);
> + perf_iommu->idx = idx;
> + perf_iommu->max_banks = amd_iommu_pc_get_max_banks(idx);
> + perf_iommu->max_counters = amd_iommu_pc_get_max_counters(idx);
> if (!perf_iommu->max_banks || !perf_iommu->max_counters)
> return -EINVAL;
>
> + snprintf(perf_iommu->name, PERF_AMD_IOMMU_NAME_SZ, "amd_iommu_%u", idx);
> +
> + perf_iommu->pmu.event_init = perf_iommu_event_init,
> + perf_iommu->pmu.add = perf_iommu_add,
> + perf_iommu->pmu.del = perf_iommu_del,
> + perf_iommu->pmu.start = perf_iommu_start,
> + perf_iommu->pmu.stop = perf_iommu_stop,
> + perf_iommu->pmu.read = perf_iommu_read,

This compiles but it is yucky.

You should do that instead:

static struct pmu amd_iommu_pmu = {
.event_init = perf_iommu_event_init,
.add = perf_iommu_add,
.del = perf_iommu_del,
.start = perf_iommu_start,
.stop = perf_iommu_stop,
.read = perf_iommu_read,
.task_ctx_nr = perf_invalid_context,
.attr_groups = amd_iommu_attr_groups,
};

...

ret = perf_pmu_register(&amd_iommu_pmu, perf_iommu->name, -1);

Because otherwise you're carrying a struct pmu in each struct
perf_amd_iommu which has identical contents.

Now, you need to access the struct perf_amd_iommu pointer for each
IOMMU PMU in some of the functions like perf_iommu_event_init(), for
example. But for that you only need the index and to iterate the
perf_amd_iommu_list.

I wasn't able to find a good way to do that from a quick stare but
PeterZ might have a better idea...

> + perf_iommu->pmu.task_ctx_nr = perf_invalid_context;
> perf_iommu->pmu.attr_groups = amd_iommu_attr_groups;
> - ret = perf_pmu_register(&perf_iommu->pmu, name, -1);
> +
> + ret = perf_pmu_register(&perf_iommu->pmu, perf_iommu->name, -1);
> if (ret)
> pr_err("Error initializing AMD IOMMU perf counters.\n");
> else
> - pr_info("perf: amd_iommu: Detected. (%d banks, %d counters/bank)\n",
> - amd_iommu_pc_get_max_banks(0),
> - amd_iommu_pc_get_max_counters(0));
> + pr_info("Detected AMD IOMMU #%d (%d banks, %d counters/bank)\n",
> + idx, amd_iommu_pc_get_max_banks(idx),
> + amd_iommu_pc_get_max_counters(idx));
> return ret;
> }
>
> -static struct perf_amd_iommu __perf_iommu = {
> - .pmu = {
> - .task_ctx_nr = perf_invalid_context,
> - .event_init = perf_iommu_event_init,
> - .add = perf_iommu_add,
> - .del = perf_iommu_del,
> - .start = perf_iommu_start,
> - .stop = perf_iommu_stop,
> - .read = perf_iommu_read,
> - },
> -};
> -
> static __init int amd_iommu_pc_init(void)
> {
> int ret;
> + unsigned int i;
> +
> + /* Init cpumask attributes to only core 0 */
> + cpumask_set_cpu(0, &iommu_cpumask);
>
> /* Make sure the IOMMU PC resource is available */
> if (!amd_iommu_pc_supported())
> @@ -470,7 +476,21 @@ static __init int amd_iommu_pc_init(void)
> if (ret)
> goto err_out;
>
> - ret = _init_perf_amd_iommu(&__perf_iommu, "amd_iommu");
> + for (i = 0 ; i < amd_iommu_get_num_iommus(); i++) {
> + struct perf_amd_iommu *pi;
> +
> + pi = kzalloc(sizeof(struct perf_amd_iommu), GFP_KERNEL);
> + if (!pi) {
> + ret = -ENOMEM;
> + break;
> + }
> +
> + list_add_tail(&pi->list, &perf_amd_iommu_list);
> + ret = init_one_perf_amd_iommu(pi, i);

You need to init *first* and iff you succeed, only *then* add to the
list.

--
Regards/Gruss,
Boris.

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