perf/x86/intel/uncore: Clean up func_id

The below warning may be triggered on GNR when the PCIE uncore units are
exposed.

WARNING: CPU: 4 PID: 1 at arch/x86/events/intel/uncore.c:1169 uncore_pci_pmu_register+0x158/0x190

The current uncore driver assumes that all the devices in the same PMU
have the exact same devfn. It's true for the previous platforms. But it
doesn't work for the new PCIE uncore units on GNR.

The assumption doesn't make sense. There is no reason to limit the
devices from the same PMU to the same devfn. Also, the current code just
throws the warning, but still registers the device. The WARN_ON_ONCE()
should be removed.

The func_id is used by the later event_init() to check if a event->pmu
has valid devices. For cpu and mmio uncore PMUs, they are always valid.
For pci uncore PMUs, it's set when the PMU is registered. It can be
replaced by the pmu->registered. Clean up the func_id.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Eric Hu <eric.hu@intel.com>
Link: https://lkml.kernel.org/r/20250108143017.1793781-1-kan.liang@linux.intel.com

Author: Kan Liang

arch/x86/events/intel/uncore.c

@@ -745,7 +745,7 @@ static int uncore_pmu_event_init(struct perf_event *event)
 
 	pmu = uncore_event_to_pmu(event);
 	/* no device found for this pmu */
-	if (pmu->func_id < 0)
+	if (!pmu->registered)
 		return -ENOENT;
 
 	/* Sampling not supported yet */
@@ -992,7 +992,7 @@ static void uncore_types_exit(struct intel_uncore_type **types)
 		uncore_type_exit(*types);
 }
 
-static int __init uncore_type_init(struct intel_uncore_type *type, bool setid)
+static int __init uncore_type_init(struct intel_uncore_type *type)
 {
 	struct intel_uncore_pmu *pmus;
 	size_t size;
@@ -1005,7 +1005,6 @@ static int __init uncore_type_init(struct intel_uncore_type *type, bool setid)
 	size = uncore_max_dies() * sizeof(struct intel_uncore_box *);
 
 	for (i = 0; i < type->num_boxes; i++) {
-		pmus[i].func_id	= setid ? i : -1;
 		pmus[i].pmu_idx	= i;
 		pmus[i].type	= type;
 		pmus[i].boxes	= kzalloc(size, GFP_KERNEL);
@@ -1055,12 +1054,12 @@ static int __init uncore_type_init(struct intel_uncore_type *type, bool setid)
 }
 
 static int __init
-uncore_types_init(struct intel_uncore_type **types, bool setid)
+uncore_types_init(struct intel_uncore_type **types)
 {
 	int ret;
 
 	for (; *types; types++) {
-		ret = uncore_type_init(*types, setid);
+		ret = uncore_type_init(*types);
 		if (ret)
 			return ret;
 	}
@@ -1160,11 +1159,6 @@ static int uncore_pci_pmu_register(struct pci_dev *pdev,
 	if (!box)
 		return -ENOMEM;
 
-	if (pmu->func_id < 0)
-		pmu->func_id = pdev->devfn;
-	else
-		WARN_ON_ONCE(pmu->func_id != pdev->devfn);
-
 	atomic_inc(&box->refcnt);
 	box->dieid = die;
 	box->pci_dev = pdev;
@@ -1410,7 +1404,7 @@ static int __init uncore_pci_init(void)
 		goto err;
 	}
 
-	ret = uncore_types_init(uncore_pci_uncores, false);
+	ret = uncore_types_init(uncore_pci_uncores);
 	if (ret)
 		goto errtype;
 
@@ -1678,7 +1672,7 @@ static int __init uncore_cpu_init(void)
 {
 	int ret;
 
-	ret = uncore_types_init(uncore_msr_uncores, true);
+	ret = uncore_types_init(uncore_msr_uncores);
 	if (ret)
 		goto err;
 
@@ -1697,7 +1691,7 @@ static int __init uncore_mmio_init(void)
 	struct intel_uncore_type **types = uncore_mmio_uncores;
 	int ret;
 
-	ret = uncore_types_init(types, true);
+	ret = uncore_types_init(types);
 	if (ret)
 		goto err;
 

arch/x86/events/intel/uncore.h

@@ -125,7 +125,6 @@ struct intel_uncore_pmu {
 	struct pmu			pmu;
 	char				name[UNCORE_PMU_NAME_LEN];
 	int				pmu_idx;
-	int				func_id;
 	bool				registered;
 	atomic_t			activeboxes;
 	cpumask_t			cpu_mask;

arch/x86/events/intel/uncore_snb.c

@@ -910,7 +910,7 @@ static int snb_uncore_imc_event_init(struct perf_event *event)
 
 	pmu = uncore_event_to_pmu(event);
 	/* no device found for this pmu */
-	if (pmu->func_id < 0)
+	if (!pmu->registered)
 		return -ENOENT;
 
 	/* Sampling not supported yet */