This patch adds multi-IOMMU support for perf by exposing
an AMD IOMMU PMU for each IOMMU found in the system via:

  /sys/device/amd_iommu_x     /* where x is the IOMMU index. */

This allows users to specify different events to be programed
onto performance counters of each IOMMU.

Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Borislav Petkov <b...@alien8.de>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpa...@amd.com>
---
 arch/x86/events/amd/iommu.c | 119 ++++++++++++++++++++++++--------------------
 1 file changed, 64 insertions(+), 55 deletions(-)

diff --git a/arch/x86/events/amd/iommu.c b/arch/x86/events/amd/iommu.c
index 2403c78..5fd97b5 100644
--- a/arch/x86/events/amd/iommu.c
+++ b/arch/x86/events/amd/iommu.c
@@ -35,10 +35,13 @@
 #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
 
 struct perf_amd_iommu {
+       struct list_head list;
        struct pmu pmu;
+       uint idx;
+       char name[PERF_AMD_IOMMU_NAME_SZ];
        u8 max_banks;
        u8 max_counters;
        u64 cntr_assign_mask;
@@ -46,6 +49,8 @@ struct perf_amd_iommu {
        const struct attribute_group *attr_groups[4];
 };
 
+LIST_HEAD(perf_amd_iommu_list);
+
 #define format_group   attr_groups[0]
 #define cpumask_group  attr_groups[1]
 #define events_group   attr_groups[2]
@@ -204,8 +209,7 @@ static int clear_avail_iommu_bnk_cntr(struct perf_amd_iommu 
*perf_iommu,
 static int perf_iommu_event_init(struct perf_event *event)
 {
        struct hw_perf_event *hwc = &event->hw;
-       struct perf_amd_iommu *perf_iommu;
-       u64 config, config1;
+       struct perf_amd_iommu *pi = container_of(event->pmu, struct 
perf_amd_iommu, pmu);
 
        /* test the event attr type check for PMU enumeration */
        if (event->attr.type != event->pmu->type)
@@ -227,27 +231,17 @@ static int perf_iommu_event_init(struct perf_event *event)
        if (event->cpu < 0)
                return -EINVAL;
 
-       perf_iommu = &__perf_iommu;
-
-       if (event->pmu != &perf_iommu->pmu)
-               return -ENOENT;
-
-       if (perf_iommu) {
-               config = event->attr.config;
-               config1 = event->attr.config1;
-       } else {
-               return -EINVAL;
-       }
-
        /* update the hw_perf_event struct with the iommu config data */
-       hwc->config = config;
-       hwc->extra_reg.config = config1;
+       hwc->idx = pi->idx;
+       hwc->config = event->attr.config;
+       hwc->extra_reg.config = event->attr.config1;
 
        return 0;
 }
 
 static void perf_iommu_enable_event(struct perf_event *ev)
 {
+       struct hw_perf_event *hwc = &ev->hw;
        u8 csource = _GET_CSOURCE(ev);
        u16 devid = _GET_DEVID(ev);
        u8 bank = _GET_BANK(ev);
@@ -255,33 +249,34 @@ static void perf_iommu_enable_event(struct perf_event *ev)
        u64 reg = 0ULL;
 
        reg = csource;
-       amd_iommu_pc_set_reg(0, devid, bank, cntr,
+       amd_iommu_pc_set_reg(hwc->idx, devid, 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, devid, bank, cntr,
+       amd_iommu_pc_set_reg(hwc->idx, devid, 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, devid, bank, cntr,
+       amd_iommu_pc_set_reg(hwc->idx, devid, 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, devid, bank, cntr,
+       amd_iommu_pc_set_reg(hwc->idx, devid, 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_DEVID(event), _GET_BANK(event),
+       amd_iommu_pc_set_reg(hwc->idx, _GET_DEVID(event), _GET_BANK(event),
                             _GET_CNTR(event), IOMMU_PC_COUNTER_SRC_REG, &reg);
 }
 
@@ -301,7 +296,7 @@ static void perf_iommu_start(struct perf_event *event, int 
flags)
 
        val = local64_read(&hwc->prev_count);
 
-       amd_iommu_pc_set_counter(0, _GET_BANK(event), _GET_CNTR(event), &val);
+       amd_iommu_pc_set_counter(hwc->idx, _GET_BANK(event), _GET_CNTR(event), 
&val);
 enable:
        perf_iommu_enable_event(event);
        perf_event_update_userpage(event);
@@ -314,7 +309,7 @@ static void perf_iommu_read(struct perf_event *event)
        s64 delta;
        struct hw_perf_event *hwc = &event->hw;
 
-       if (amd_iommu_pc_get_counter(0, _GET_BANK(event), _GET_CNTR(event), 
&cnt))
+       if (amd_iommu_pc_get_counter(hwc->idx, _GET_BANK(event), 
_GET_CNTR(event), &cnt))
                return;
 
        /* IOMMU pc counter register is only 48 bits */
@@ -417,14 +412,20 @@ static __init int _init_events_attrs(struct 
perf_amd_iommu *perf_iommu)
 
 static __init void amd_iommu_pc_exit(void)
 {
-       if (__perf_iommu.events_group != NULL) {
-               kfree(__perf_iommu.events_group);
-               __perf_iommu.events_group = NULL;
+       struct perf_amd_iommu *pi, *next;
+
+       list_for_each_entry_safe(pi, next, &perf_amd_iommu_list, list) {
+               list_del(&pi->list);
+
+               kfree(pi->events_group);
+               pi->events_group = NULL;
+
+               kfree(pi);
        }
 }
 
-static __init int _init_perf_amd_iommu(
-       struct perf_amd_iommu *perf_iommu, char *name)
+static __init int
+init_one_perf_amd_iommu(struct perf_amd_iommu *perf_iommu, uint idx)
 {
        int ret;
 
@@ -441,54 +442,62 @@ static __init int _init_perf_amd_iommu(
        if (_init_events_attrs(perf_iommu) != 0)
                pr_err("Only support raw events.\n");
 
-       perf_iommu->max_banks = amd_iommu_pc_get_max_banks(0);
-       perf_iommu->max_counters = amd_iommu_pc_get_max_counters(0);
+       snprintf(perf_iommu->name, PERF_AMD_IOMMU_NAME_SZ, "amd_iommu_%u", idx);
+       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;
 
        /* Init null attributes */
        perf_iommu->null_group = NULL;
+
+       /* Setting up PMU */
+       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,
+       perf_iommu->pmu.task_ctx_nr = perf_invalid_context;
        perf_iommu->pmu.attr_groups = perf_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");
                amd_iommu_pc_exit();
        } 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 %s, w/ %d banks, %d counters/bank\n",
+                       perf_iommu->name,
+                       amd_iommu_pc_get_max_banks(idx),
+                       amd_iommu_pc_get_max_counters(idx));
+
+               list_add_tail(&perf_iommu->list, &perf_amd_iommu_list);
        }
 
        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,
-       },
-       .max_banks              = 0x00,
-       .max_counters           = 0x00,
-       .cntr_assign_mask       = 0ULL,
-       .format_group           = NULL,
-       .cpumask_group          = NULL,
-       .events_group           = NULL,
-       .null_group             = NULL,
-};
-
 static __init int amd_iommu_pc_init(void)
 {
+       uint i;
+
        /* Make sure the IOMMU PC resource is available */
        if (!amd_iommu_pc_supported())
                return -ENODEV;
 
-       _init_perf_amd_iommu(&__perf_iommu, "amd_iommu");
+       for (i = 0 ; i < amd_iommu_get_num_iommus(); i++) {
+               int ret;
+               struct perf_amd_iommu *pi;
+
+               pi = kzalloc(sizeof(struct perf_amd_iommu), GFP_KERNEL);
+               if (!pi)
+                       return -ENOMEM;
+
+               ret = init_one_perf_amd_iommu(pi, i);
+               if (ret)
+                       return ret;
+       }
 
        return 0;
 }
-- 
1.8.3.1

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