[PATCH RFC v4 08/16] drm, cgroup: Add peak GEM buffer allocation limit

[Kenny Ho]

drm.buffer.peak.default
        A read-only flat-keyed file which exists on the root cgroup.
        Each entry is keyed by the drm device's major:minor.

        Default limits on the largest GEM buffer allocation in bytes.

drm.buffer.peak.max
        A read-write flat-keyed file which exists on all cgroups.  Each
        entry is keyed by the drm device's major:minor.

        Per device limits on the largest GEM buffer allocation in bytes.
        This is a hard limit.  Attempts in allocating beyond the cgroup
        limit will result in ENOMEM.  Shorthand understood by memparse
        (such as k, m, g) can be used.

        Set largest allocation for /dev/dri/card1 to 4MB
        echo "226:1 4m" > drm.buffer.peak.max

Change-Id: I0830d56775568e1cf215b56cc892d5e7945e9f25
Signed-off-by: Kenny Ho <Kenny.Ho at amd.com>
---
 Documentation/admin-guide/cgroup-v2.rst | 18 ++++++++++
 include/drm/drm_cgroup.h                |  1 +
 include/linux/cgroup_drm.h              |  1 +
 kernel/cgroup/drm.c                     | 48 +++++++++++++++++++++++++
 4 files changed, 68 insertions(+)

diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index e8fac2684179..87a195133eaa 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -1940,6 +1940,24 @@ DRM Interface Files
 	Set allocation limit for /dev/dri/card0 to 512MB
 	echo "226:0 512m" > drm.buffer.total.max
 
+  drm.buffer.peak.default
+	A read-only flat-keyed file which exists on the root cgroup.
+	Each entry is keyed by the drm device's major:minor.
+
+	Default limits on the largest GEM buffer allocation in bytes.
+    
+  drm.buffer.peak.max
+	A read-write flat-keyed file which exists on all cgroups.  Each
+	entry is keyed by the drm device's major:minor.
+
+	Per device limits on the largest GEM buffer allocation in bytes.
+	This is a hard limit.  Attempts in allocating beyond the cgroup
+	limit will result in ENOMEM.  Shorthand understood by memparse
+	(such as k, m, g) can be used.
+
+	Set largest allocation for /dev/dri/card1 to 4MB
+	echo "226:1 4m" > drm.buffer.peak.max
+
 GEM Buffer Ownership
 ~~~~~~~~~~~~~~~~~~~~
 
diff --git a/include/drm/drm_cgroup.h b/include/drm/drm_cgroup.h
index 49c5d35ff6e1..d61b90beded5 100644
--- a/include/drm/drm_cgroup.h
+++ b/include/drm/drm_cgroup.h
@@ -14,6 +14,7 @@ struct drmcg_props {
 	bool			limit_enforced;
 
 	s64			bo_limits_total_allocated_default;
+	s64			bo_limits_peak_allocated_default;
 };
 
 #ifdef CONFIG_CGROUP_DRM
diff --git a/include/linux/cgroup_drm.h b/include/linux/cgroup_drm.h
index eb54e56f20ae..87a2566c9fdd 100644
--- a/include/linux/cgroup_drm.h
+++ b/include/linux/cgroup_drm.h
@@ -29,6 +29,7 @@ struct drmcg_device_resource {
 	s64			bo_limits_total_allocated;
 
 	s64			bo_stats_peak_allocated;
+	s64			bo_limits_peak_allocated;
 
 	s64			bo_stats_count_allocated;
 };
diff --git a/kernel/cgroup/drm.c b/kernel/cgroup/drm.c
index 7161fa40e156..2f54bff291e5 100644
--- a/kernel/cgroup/drm.c
+++ b/kernel/cgroup/drm.c
@@ -75,6 +75,9 @@ static inline int init_drmcg_single(struct drmcg *drmcg, struct drm_device *dev)
 	ddr->bo_limits_total_allocated =
 		dev->drmcg_props.bo_limits_total_allocated_default;
 
+	ddr->bo_limits_peak_allocated =
+		dev->drmcg_props.bo_limits_peak_allocated_default;
+
 	mutex_unlock(&dev->drmcg_mutex);
 	return 0;
 }
@@ -157,6 +160,9 @@ static void drmcg_print_limits(struct drmcg_device_resource *ddr,
 	case DRMCG_TYPE_BO_TOTAL:
 		seq_printf(sf, "%lld\n", ddr->bo_limits_total_allocated);
 		break;
+	case DRMCG_TYPE_BO_PEAK:
+		seq_printf(sf, "%lld\n", ddr->bo_limits_peak_allocated);
+		break;
 	default:
 		seq_puts(sf, "\n");
 		break;
@@ -171,6 +177,10 @@ static void drmcg_print_default(struct drmcg_props *props,
 		seq_printf(sf, "%lld\n",
 			props->bo_limits_total_allocated_default);
 		break;
+	case DRMCG_TYPE_BO_PEAK:
+		seq_printf(sf, "%lld\n",
+			props->bo_limits_peak_allocated_default);
+		break;
 	default:
 		seq_puts(sf, "\n");
 		break;
@@ -327,6 +337,24 @@ static ssize_t drmcg_limit_write(struct kernfs_open_file *of, char *buf,
 			drmcg_value_apply(dm->dev,
 					&ddr->bo_limits_total_allocated, val);
 			break;
+		case DRMCG_TYPE_BO_PEAK:
+			p_max = parent == NULL ? S64_MAX :
+				parent->dev_resources[minor]->
+				bo_limits_peak_allocated;
+
+			rc = drmcg_process_limit_s64_val(sattr, true,
+				props->bo_limits_peak_allocated_default,
+				p_max,
+				&val);
+
+			if (rc || val < 0) {
+				drmcg_pr_cft_err(drmcg, rc, cft_name, minor);
+				break;
+			}
+
+			drmcg_value_apply(dm->dev,
+					&ddr->bo_limits_peak_allocated, val);
+			break;
 		default:
 			break;
 		}
@@ -363,6 +391,20 @@ struct cftype files[] = {
 		.private = DRMCG_CTF_PRIV(DRMCG_TYPE_BO_PEAK,
 						DRMCG_FTYPE_STATS),
 	},
+	{
+		.name = "buffer.peak.default",
+		.seq_show = drmcg_seq_show,
+		.flags = CFTYPE_ONLY_ON_ROOT,
+		.private = DRMCG_CTF_PRIV(DRMCG_TYPE_BO_PEAK,
+						DRMCG_FTYPE_DEFAULT),
+	},
+	{
+		.name = "buffer.peak.max",
+		.write = drmcg_limit_write,
+		.seq_show = drmcg_seq_show,
+		.private = DRMCG_CTF_PRIV(DRMCG_TYPE_BO_PEAK,
+						DRMCG_FTYPE_LIMIT),
+	},
 	{
 		.name = "buffer.count.stats",
 		.seq_show = drmcg_seq_show,
@@ -427,6 +469,7 @@ void drmcg_device_early_init(struct drm_device *dev)
 	dev->drmcg_props.limit_enforced = false;
 
 	dev->drmcg_props.bo_limits_total_allocated_default = S64_MAX;
+	dev->drmcg_props.bo_limits_peak_allocated_default = S64_MAX;
 
 	drmcg_update_cg_tree(dev);
 }
@@ -466,6 +509,11 @@ bool drmcg_try_chg_bo_alloc(struct drmcg *drmcg, struct drm_device *dev,
 				result = false;
 				break;
 			}
+
+			if (ddr->bo_limits_peak_allocated < size) {
+				result = false;
+				break;
+			}
 		}
 	}
 
-- 
2.22.0