drm/i915: Disable Secure Batches for gen6+

commit 44157641d448cbc0c4b73c5231d2b911f0cb0427 upstream.

Retroactively stop reporting support for secure batches
through the api for gen6+ so that older binaries trigger
the fallback path instead.

Older binaries use secure batches pre gen6 to access resources
that are not available to normal usermode processes. However,
all known userspace explicitly checks for HAS_SECURE_BATCHES
before relying on the secure batch feature.

Since there are no known binaries relying on this for newer gens
we can kill secure batches from gen6, via I915_PARAM_HAS_SECURE_BATCHES.

v2: rebase (Mika)
v3: rebase (Mika)
Signed-off-by: NJon Bloomfield <jon.bloomfield@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: NChris Wilson <chris.p.wilson@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpu/drm/i915/i915_drv.c

@@ -351,7 +351,7 @@ static int i915_getparam_ioctl(struct drm_device *dev, void *data,
 		value = HAS_LEGACY_SEMAPHORES(dev_priv);
 		break;
 	case I915_PARAM_HAS_SECURE_BATCHES:
-		value = capable(CAP_SYS_ADMIN);
+		value = HAS_SECURE_BATCHES(dev_priv) && capable(CAP_SYS_ADMIN);
 		break;
 	case I915_PARAM_CMD_PARSER_VERSION:
 		value = i915_cmd_parser_get_version(dev_priv);

drivers/gpu/drm/i915/i915_drv.h

@@ -2517,6 +2517,8 @@ intel_info(const struct drm_i915_private *dev_priv)
 
 #define HAS_LEGACY_SEMAPHORES(dev_priv) IS_GEN7(dev_priv)
 
+#define HAS_SECURE_BATCHES(dev_priv) (INTEL_GEN(dev_priv) < 6)
+
 #define HAS_LLC(dev_priv)	((dev_priv)->info.has_llc)
 #define HAS_SNOOP(dev_priv)	((dev_priv)->info.has_snoop)
 #define HAS_EDRAM(dev_priv)	(!!((dev_priv)->edram_cap & EDRAM_ENABLED))

drivers/gpu/drm/i915/i915_gem_execbuffer.c

@@ -2177,6 +2177,7 @@ i915_gem_do_execbuffer(struct drm_device *dev,
 		       struct drm_i915_gem_exec_object2 *exec,
 		       struct drm_syncobj **fences)
 {
+	struct drm_i915_private *i915 = to_i915(dev);
 	struct i915_execbuffer eb;
 	struct dma_fence *in_fence = NULL;
 	struct sync_file *out_fence = NULL;
@@ -2187,7 +2188,7 @@ i915_gem_do_execbuffer(struct drm_device *dev,
 	BUILD_BUG_ON(__EXEC_OBJECT_INTERNAL_FLAGS &
 		     ~__EXEC_OBJECT_UNKNOWN_FLAGS);
 
-	eb.i915 = to_i915(dev);
+	eb.i915 = i915;
 	eb.file = file;
 	eb.args = args;
 	if (DBG_FORCE_RELOC || !(args->flags & I915_EXEC_NO_RELOC))
@@ -2209,8 +2210,15 @@ i915_gem_do_execbuffer(struct drm_device *dev,
 
 	eb.batch_flags = 0;
 	if (args->flags & I915_EXEC_SECURE) {
+		if (INTEL_GEN(i915) >= 11)
+			return -ENODEV;
+
+		/* Return -EPERM to trigger fallback code on old binaries. */
+		if (!HAS_SECURE_BATCHES(i915))
+			return -EPERM;
+
 		if (!drm_is_current_master(file) || !capable(CAP_SYS_ADMIN))
-		    return -EPERM;
+			return -EPERM;
 
 		eb.batch_flags |= I915_DISPATCH_SECURE;
 	}