From 770b812072e8be6a929e77836011c4d5a98509ae Mon Sep 17 00:00:00 2001
From: Jon Bloomfield <jon.bloomfield@intel.com>
Date: Wed, 1 Aug 2018 09:33:59 -0700
Subject: [PATCH 13/23] drm/i915: Add support for mandatory cmdparsing
Git-commit: 311a50e76a33d1e029563c24b2ff6db0c02b5afe
Patch-mainline: v5.4-rc8
References: CVE-2019-0154,bsc#1135966,CVE-2019-0155,bsc#1135967

The existing cmdparser for gen7 can be bypassed by specifying
batch_len=0 in the execbuf call. This is safe because bypassing
simply reduces the cmd-set available.

In a later patch we will introduce cmdparsing for gen9, as a
security measure, which must be strictly enforced since without
it we are vulnerable to DoS attacks.

Introduce the concept of 'required' cmd parsing that cannot be
bypassed by submitting zero-length bb's.

Signed-off-by: Jon Bloomfield <jon.bloomfield@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/i915/i915_cmd_parser.c     |    6 +++---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |    3 ++-
 drivers/gpu/drm/i915/intel_ringbuffer.h    |   17 ++++++++++++-----
 3 files changed, 17 insertions(+), 9 deletions(-)

--- a/drivers/gpu/drm/i915/i915_cmd_parser.c
+++ b/drivers/gpu/drm/i915/i915_cmd_parser.c
@@ -916,7 +916,7 @@ void intel_engine_init_cmd_parser(struct
 		return;
 	}
 
-	engine->flags |= I915_ENGINE_NEEDS_CMD_PARSER;
+	engine->flags |= I915_ENGINE_USING_CMD_PARSER;
 }
 
 /**
@@ -928,7 +928,7 @@ void intel_engine_init_cmd_parser(struct
  */
 void intel_engine_cleanup_cmd_parser(struct intel_engine_cs *engine)
 {
-	if (!intel_engine_needs_cmd_parser(engine))
+	if (!intel_engine_using_cmd_parser(engine))
 		return;
 
 	fini_hash_table(engine);
@@ -1317,7 +1317,7 @@ int i915_cmd_parser_get_version(struct d
 
 	/* If the command parser is not enabled, report 0 - unsupported */
 	for_each_engine(engine, dev_priv, id) {
-		if (intel_engine_needs_cmd_parser(engine)) {
+		if (intel_engine_using_cmd_parser(engine)) {
 			active = true;
 			break;
 		}
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -309,7 +309,8 @@ static inline u64 gen8_noncanonical_addr
 
 static inline bool eb_use_cmdparser(const struct i915_execbuffer *eb)
 {
-	return intel_engine_needs_cmd_parser(eb->engine) && eb->batch_len;
+	return intel_engine_requires_cmd_parser(eb->engine) ||
+		(intel_engine_using_cmd_parser(eb->engine) && eb->batch_len);
 }
 
 static int eb_create(struct i915_execbuffer *eb)
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -570,9 +570,10 @@ struct intel_engine_cs {
 
 	struct intel_engine_hangcheck hangcheck;
 
-#define I915_ENGINE_NEEDS_CMD_PARSER BIT(0)
-#define I915_ENGINE_SUPPORTS_STATS   BIT(1)
-#define I915_ENGINE_HAS_PREEMPTION   BIT(2)
+#define I915_ENGINE_USING_CMD_PARSER	BIT(0)
+#define I915_ENGINE_SUPPORTS_STATS	BIT(1)
+#define I915_ENGINE_HAS_PREEMPTION	BIT(2)
+#define I915_ENGINE_REQUIRES_CMD_PARSER	BIT(3)
 	unsigned int flags;
 
 	/*
@@ -633,9 +634,15 @@ struct intel_engine_cs {
 };
 
 static inline bool
-intel_engine_needs_cmd_parser(const struct intel_engine_cs *engine)
+intel_engine_using_cmd_parser(const struct intel_engine_cs *engine)
 {
-	return engine->flags & I915_ENGINE_NEEDS_CMD_PARSER;
+	return engine->flags & I915_ENGINE_USING_CMD_PARSER;
+}
+
+static inline bool
+intel_engine_requires_cmd_parser(const struct intel_engine_cs *engine)
+{
+	return engine->flags & I915_ENGINE_REQUIRES_CMD_PARSER;
 }
 
 static inline bool