arm64/mpam: Summarize feature support during mpam_enable()

hulk inclusion
category: feature
feature: ARM MPAM support
bugzilla: 48265
CVE: NA

--------------------------------

To make a decision about whether to expose an mpam class as
a resctrl resource we need to know its overall supported
features and properties.

Once we've probed all the devices, we can walk the tree
and produced overall values. If bitmap properties are mismatched
within a component we cannot support that bitmap.

[Wang ShaoBo: few version adaption changes]
Signed-off-by: NJames Morse <james.morse@arm.com>
Link: http://www.linux-arm.org/git?p=linux-jm.git;a=patch;h=96d7c0b933c0334abf9c45d73f239ac3f382c074Signed-off-by: NWang ShaoBo <bobo.shaobowang@huawei.com>
Reviewed-by: NXiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: NCheng Jian <cj.chengjian@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/arm64/kernel/mpam/mpam_device.c

@@ -252,6 +252,112 @@ static int mpam_device_probe(struct mpam_device *dev)
 	return 0;
 }
 
+/*
+ * If device doesn't match class feature/configuration, do the right thing.
+ * For 'num' properties we can just take the minimum.
+ * For properties where the mismatched unused bits would make a difference, we
+ * nobble the class feature, as we can't configure all the devices.
+ * e.g. The L3 cache is composed of two devices with 13 and 17 portion
+ * bitmaps respectively.
+ */
+static void __device_class_feature_mismatch(struct mpam_device *dev,
+					struct mpam_class *class)
+{
+	lockdep_assert_held(&mpam_devices_lock); /* we modify class */
+
+	if (class->cpbm_wd != dev->cpbm_wd)
+		mpam_clear_feature(mpam_feat_cpor_part, &class->features);
+	if (class->mbw_pbm_bits != dev->mbw_pbm_bits)
+		mpam_clear_feature(mpam_feat_mbw_part, &class->features);
+
+	/* For num properties, take the minimum */
+	if (class->num_partid != dev->num_partid)
+		class->num_partid = min(class->num_partid, dev->num_partid);
+	if (class->num_intpartid != dev->num_intpartid)
+		class->num_intpartid = min(class->num_intpartid, dev->num_intpartid);
+	if (class->num_pmg != dev->num_pmg)
+		class->num_pmg = min(class->num_pmg, dev->num_pmg);
+	if (class->num_csu_mon != dev->num_csu_mon)
+		class->num_csu_mon = min(class->num_csu_mon, dev->num_csu_mon);
+	if (class->num_mbwu_mon != dev->num_mbwu_mon)
+		class->num_mbwu_mon = min(class->num_mbwu_mon,
+			dev->num_mbwu_mon);
+
+	/* bwa_wd is a count of bits, fewer bits means less precision */
+	if (class->bwa_wd != dev->bwa_wd)
+		class->bwa_wd = min(class->bwa_wd, dev->bwa_wd);
+
+	if (class->intpri_wd != dev->intpri_wd)
+		class->intpri_wd = min(class->intpri_wd, dev->intpri_wd);
+	if (class->dspri_wd != dev->dspri_wd)
+		class->dspri_wd = min(class->dspri_wd, dev->dspri_wd);
+
+	/* {int,ds}pri may not have differing 0-low behaviour */
+	if (mpam_has_feature(mpam_feat_intpri_part_0_low, class->features) !=
+		mpam_has_feature(mpam_feat_intpri_part_0_low, dev->features))
+		mpam_clear_feature(mpam_feat_intpri_part, &class->features);
+	if (mpam_has_feature(mpam_feat_dspri_part_0_low, class->features) !=
+		mpam_has_feature(mpam_feat_dspri_part_0_low, dev->features))
+		mpam_clear_feature(mpam_feat_dspri_part, &class->features);
+}
+
+/*
+ * Squash common class=>component=>device->features down to the
+ * class->features
+ */
+static void mpam_enable_squash_features(void)
+{
+	unsigned long flags;
+	struct mpam_device *dev;
+	struct mpam_class *class;
+	struct mpam_component *comp;
+
+	lockdep_assert_held(&mpam_devices_lock);
+
+	list_for_each_entry(class, &mpam_classes, classes_list) {
+		/*
+		 * Copy the first component's first device's properties and
+		 * features to the class. __device_class_feature_mismatch()
+		 * will fix them as appropriate.
+		 * It is not possible to have a component with no devices.
+		 */
+		if (!list_empty(&class->components)) {
+			comp = list_first_entry_or_null(&class->components,
+					struct mpam_component, class_list);
+			if (WARN_ON(!comp))
+				break;
+
+			dev = list_first_entry_or_null(&comp->devices,
+						struct mpam_device, comp_list);
+			if (WARN_ON(!dev))
+				break;
+
+			spin_lock_irqsave(&dev->lock, flags);
+			class->features = dev->features;
+			class->cpbm_wd = dev->cpbm_wd;
+			class->mbw_pbm_bits = dev->mbw_pbm_bits;
+			class->bwa_wd = dev->bwa_wd;
+			class->intpri_wd = dev->intpri_wd;
+			class->dspri_wd = dev->dspri_wd;
+			class->num_partid = dev->num_partid;
+			class->num_intpartid = dev->num_intpartid;
+			class->num_pmg = dev->num_pmg;
+			class->num_csu_mon = dev->num_csu_mon;
+			class->num_mbwu_mon = dev->num_mbwu_mon;
+			spin_unlock_irqrestore(&dev->lock, flags);
+		}
+
+		list_for_each_entry(comp, &class->components, class_list) {
+			list_for_each_entry(dev, &comp->devices, comp_list) {
+				spin_lock_irqsave(&dev->lock, flags);
+				__device_class_feature_mismatch(dev, class);
+				class->features &= dev->features;
+				spin_unlock_irqrestore(&dev->lock, flags);
+			}
+		}
+	}
+}
+
 /*
  * Enable mpam once all devices have been probed.
  * Scheduled by mpam_discovery_complete() once all devices have been created.
@@ -278,6 +384,10 @@ static void __init mpam_enable(struct work_struct *work)
 
 	if (!all_devices_probed)
 		return;
+
+	mutex_lock(&mpam_devices_lock);
+	mpam_enable_squash_features();
+	mutex_unlock(&mpam_devices_lock);
 }
 
 static void mpam_failed(struct work_struct *work)

arch/arm64/kernel/mpam/mpam_device.h

@@ -98,10 +98,25 @@ struct mpam_class {
 	u8                      level;
 	enum mpam_class_types   type;
 
+	/* Once enabled, the common features */
+	u32                     features;
+
 	struct mutex            lock;
 
 	/* member of mpam_classes */
 	struct list_head        classes_list;
+
+	u16                     cmax_wd;
+	u16                     cpbm_wd;
+	u16                     mbw_pbm_bits;
+	u16                     bwa_wd;
+	u16                     intpri_wd;
+	u16                     dspri_wd;
+	u16                     num_partid;
+	u16                     num_intpartid;
+	u16                     num_pmg;
+	u16                     num_csu_mon;
+	u16                     num_mbwu_mon;
 };
 
 /* System wide properties */