[PATCH v12 10/10] perf/amd/iommu: Enable support for multiple IOMMUs

[Suravee Suthikulpanit <Suravee.Suthikulpanit-5C7GfCeVMHo@public.gmane.org>]

From: Suravee Suthikulpanit <suravee.suthikulpanit-5C7GfCeVMHo@public.gmane.org>

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 programmed onto performance counters
of each IOMMU.

Cc: Borislav Petkov <bp-Gina5bIWoIWzQB+pC5nmwQ@public.gmane.org>
Cc: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit-5C7GfCeVMHo@public.gmane.org>
---
 arch/x86/events/amd/iommu.c | 111 ++++++++++++++++++++++++++++----------------
 1 file changed, 70 insertions(+), 41 deletions(-)

diff --git a/arch/x86/events/amd/iommu.c b/arch/x86/events/amd/iommu.c
index 915a20c..9a12077 100644
--- a/arch/x86/events/amd/iommu.c
+++ b/arch/x86/events/amd/iommu.c
@@ -34,16 +34,21 @@
 #define GET_DOMID_MASK(x)  ((x->conf1 >> 16) & 0xFFFFULL)
 #define GET_PASID_MASK(x)  ((x->conf1 >> 32) & 0xFFFFFULL)
 
-static struct perf_amd_iommu __perf_iommu;
+#define PERF_AMD_IOMMU_NAME_SIZE	16
 
 struct perf_amd_iommu {
+	struct list_head list;
 	struct pmu pmu;
+	struct amd_iommu *iommu;
+	char name[PERF_AMD_IOMMU_NAME_SIZE];
 	u8 max_banks;
 	u8 max_counters;
 	u64 cntr_assign_mask;
 	raw_spinlock_t lock;
 };
 
+static LIST_HEAD(perf_amd_iommu_list);
+
 /*---------------------------------------------
  * sysfs format attributes
  *---------------------------------------------*/
@@ -234,9 +239,14 @@ static int perf_iommu_event_init(struct perf_event *event)
 	return 0;
 }
 
+static inline struct amd_iommu *perf_event_2_iommu(struct perf_event *ev)
+{
+	return (container_of(ev->pmu, struct perf_amd_iommu, pmu))->iommu;
+}
+
 static void perf_iommu_enable_event(struct perf_event *ev)
 {
-	struct amd_iommu *iommu = get_amd_iommu(0);
+	struct amd_iommu *iommu = perf_event_2_iommu(ev);
 	struct hw_perf_event *hwc = &ev->hw;
 	u8 bank = hwc->iommu_bank;
 	u8 cntr = hwc->iommu_cntr;
@@ -266,7 +276,7 @@ static void perf_iommu_enable_event(struct perf_event *ev)
 
 static void perf_iommu_disable_event(struct perf_event *event)
 {
-	struct amd_iommu *iommu = get_amd_iommu(0);
+	struct amd_iommu *iommu = perf_event_2_iommu(event);
 	struct hw_perf_event *hwc = &event->hw;
 	u64 reg = 0ULL;
 
@@ -286,7 +296,7 @@ static void perf_iommu_start(struct perf_event *event, int flags)
 
 	if (flags & PERF_EF_RELOAD) {
 		u64 prev_raw_count = local64_read(&hwc->prev_count);
-		struct amd_iommu *iommu = get_amd_iommu(0);
+		struct amd_iommu *iommu = perf_event_2_iommu(event);
 
 		amd_iommu_pc_set_reg(iommu, hwc->iommu_bank, hwc->iommu_cntr,
 				     IOMMU_PC_COUNTER_REG, &prev_raw_count);
@@ -301,7 +311,7 @@ static void perf_iommu_read(struct perf_event *event)
 {
 	u64 count, prev, delta;
 	struct hw_perf_event *hwc = &event->hw;
-	struct amd_iommu *iommu = get_amd_iommu(0);
+	struct amd_iommu *iommu = perf_event_2_iommu(event);
 
 	if (amd_iommu_pc_get_reg(iommu, hwc->iommu_bank, hwc->iommu_cntr,
 				 IOMMU_PC_COUNTER_REG, &count))
@@ -389,11 +399,6 @@ static __init int _init_events_attrs(void)
 	return 0;
 }
 
-static __init void amd_iommu_pc_exit(void)
-{
-	kfree(amd_iommu_events_group.attrs);
-}
-
 const struct attribute_group *amd_iommu_attr_groups[] = {
 	&amd_iommu_format_group,
 	&amd_iommu_cpumask_group,
@@ -401,47 +406,56 @@ static __init void amd_iommu_pc_exit(void)
 	NULL,
 };
 
+static struct pmu 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,
+};
+
 static __init int
-_init_perf_amd_iommu(struct perf_amd_iommu *perf_iommu, char *name)
+init_one_iommu(unsigned int idx)
 {
 	int ret;
+	struct perf_amd_iommu *perf_iommu;
 
-	raw_spin_lock_init(&perf_iommu->lock);
+	perf_iommu = kzalloc(sizeof(struct perf_amd_iommu), GFP_KERNEL);
+	if (!perf_iommu)
+		return -ENOMEM;
 
-	/* Init cpumask attributes to only core 0 */
-	cpumask_set_cpu(0, &iommu_cpumask);
+	raw_spin_lock_init(&perf_iommu->lock);
 
-	perf_iommu->max_banks    = amd_iommu_pc_get_max_banks(0);
-	perf_iommu->max_counters = amd_iommu_pc_get_max_counters(0);
-	if (!perf_iommu->max_banks || !perf_iommu->max_counters)
+	perf_iommu->pmu          = iommu_pmu;
+	perf_iommu->iommu        = get_amd_iommu(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->iommu || !perf_iommu->max_banks ||
+	    !perf_iommu->max_counters) {
+		kfree(perf_iommu);
 		return -EINVAL;
+	}
 
-	perf_iommu->pmu.attr_groups = amd_iommu_attr_groups;
-	ret = perf_pmu_register(&perf_iommu->pmu, name, -1);
-	if (ret)
-		pr_err("Error initializing AMD IOMMU perf counters.\n");
-	else
-		pr_info("Detected AMD IOMMU (%d banks, %d counters/bank).\n",
-			amd_iommu_pc_get_max_banks(0),
-			amd_iommu_pc_get_max_counters(0));
+	snprintf(perf_iommu->name, PERF_AMD_IOMMU_NAME_SIZE, "amd_iommu_%u", idx);
+	ret = perf_pmu_register(&perf_iommu->pmu, perf_iommu->name, -1);
+	if (!ret) {
+		pr_info("Detected AMD IOMMU #%d (%d banks, %d counters/bank).\n",
+			idx, perf_iommu->max_banks, perf_iommu->max_counters);
+		list_add_tail(&perf_iommu->list, &perf_amd_iommu_list);
+	} else {
+		pr_warn("Error initializing IOMMU %d.\n", idx);
+		kfree(perf_iommu);
+	}
 	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, cnt = 0;
 
 	/* Make sure the IOMMU PC resource is available */
 	if (!amd_iommu_pc_supported())
@@ -451,11 +465,26 @@ static __init int amd_iommu_pc_init(void)
 	if (ret)
 		return ret;
 
-	ret = _init_perf_amd_iommu(&__perf_iommu, "amd_iommu");
-	if (ret)
-		amd_iommu_pc_exit();
+	/*
+	 * An IOMMU PMU is specific to each IOMMU, and can
+	 * function independently. So, we go through all IOMMUs
+	 * and ignore the one that fails initialization unless
+	 * all IOMMU are failing.
+	 */
+	for (i = 0; i < amd_iommu_get_num_iommus(); i++) {
+		ret = init_one_iommu(i);
+		if (!ret)
+			cnt++;
+	}
 
-	return ret;
+	if (!cnt) {
+		kfree(amd_iommu_events_group.attrs);
+		return -ENODEV;
+	}
+
+	/* Init cpumask attributes to only core 0 */
+	cpumask_set_cpu(0, &iommu_cpumask);
+	return 0;
 }
 
 device_initcall(amd_iommu_pc_init);
-- 
1.8.3.1