[Intel-gfx] [PATCH 10/10] drm/i915: Disable use of stolen area by User when Intel RST is present

[ankitprasad.r.sharma at intel.com]

From: Ankitprasad Sharma <ankitprasad.r.sharma at intel.com>

The BIOS RapidStartTechnology may corrupt the stolen memory across S3
suspend due to unalarmed hibernation, in which case we will not be able
to preserve the User data stored in the stolen region. Hence this patch
tries to identify presence of the RST device on the ACPI bus, and
disables use of stolen memory (for persistent data) if found.

Signed-off-by: Ankitprasad Sharma <ankitprasad.r.sharma at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h        |  7 +++++++
 drivers/gpu/drm/i915/i915_gem.c        |  8 ++++++++
 drivers/gpu/drm/i915/i915_gem_stolen.c | 14 ++++++++++++++
 drivers/gpu/drm/i915/intel_acpi.c      | 20 ++++++++++++++++++++
 4 files changed, 49 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 492878a..d26a8f1 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1309,6 +1309,9 @@ struct i915_gem_mm {
 	 */
 	bool busy;
 
+	/* Intel RapidStart Technology info */
+	bool nonvolatile_stolen;
+
 	/* the indicator for dispatch video commands on two BSD rings */
 	int bsd_ring_dispatch_index;
 
@@ -3417,9 +3420,13 @@ intel_opregion_notify_adapter(struct drm_device *dev, pci_power_t state)
 #ifdef CONFIG_ACPI
 extern void intel_register_dsm_handler(void);
 extern void intel_unregister_dsm_handler(void);
+extern bool intel_detect_acpi_rst(void);
+extern int match_device(struct device *dev, void* ids);
 #else
 static inline void intel_register_dsm_handler(void) { return; }
 static inline void intel_unregister_dsm_handler(void) { return; }
+static inline bool intel_detect_acpi_rst(void) { return false; }
+static int match_device(struct device *dev, void* ids) { return 0; }
 #endif /* CONFIG_ACPI */
 
 /* modesetting */
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index d27a41e..daca05f 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -399,6 +399,7 @@ i915_gem_create(struct drm_file *file,
 		uint32_t *handle_p)
 {
 	struct drm_i915_gem_object *obj;
+	struct drm_i915_private *dev_priv = dev->dev_private;
 	int ret;
 	u32 handle;
 
@@ -411,6 +412,13 @@ i915_gem_create(struct drm_file *file,
 
 	/* Allocate the new object */
 	if (flags & I915_CREATE_PLACEMENT_STOLEN) {
+		if (!dev_priv->mm.nonvolatile_stolen) {
+			/* Stolen may be overwritten by external parties
+			 * so unsuitable for persistent user data.
+			 */
+			return -ENODEV;
+		}
+
 		mutex_lock(&dev->struct_mutex);
 		obj = i915_gem_object_create_stolen(dev, size);
 		if (IS_ERR(obj)) {
diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
index 6d1af9d..98b4998 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -482,6 +482,20 @@ int i915_gem_init_stolen(struct drm_device *dev)
 	 */
 	drm_mm_init(&dev_priv->mm.stolen, 0, dev_priv->gtt.stolen_usable_size);
 
+	/* If the stolen region can be modified behind our backs upon suspend,
+	 * then we cannot use it to store nonvolatile contents (i.e user data)
+	 * as it will be corrupted upon resume.
+	 */
+	dev_priv->mm.nonvolatile_stolen = true;
+#ifdef CONFIG_SUSPEND
+	if (intel_detect_acpi_rst()) {
+		/* BIOSes using RapidStart Technology have been reported
+		 * to overwrite stolen across S3, not just S4.
+		 */
+		dev_priv->mm.nonvolatile_stolen = false;
+	}
+#endif
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/i915/intel_acpi.c b/drivers/gpu/drm/i915/intel_acpi.c
index eb638a1..5f7713d 100644
--- a/drivers/gpu/drm/i915/intel_acpi.c
+++ b/drivers/gpu/drm/i915/intel_acpi.c
@@ -23,6 +23,11 @@ static const u8 intel_dsm_guid[] = {
 	0x0f, 0x13, 0x17, 0xb0, 0x1c, 0x2c
 };
 
+static const struct acpi_device_id irst_ids[] = {
+	{"INT3392", 0},
+	{"", 0}
+};
+
 static char *intel_dsm_port_name(u8 id)
 {
 	switch (id) {
@@ -162,3 +167,18 @@ void intel_register_dsm_handler(void)
 void intel_unregister_dsm_handler(void)
 {
 }
+
+int match_device(struct device *dev, void* ids)
+{
+	if (acpi_match_device(irst_ids, dev))
+		return 1;
+
+	return 0;
+}
+bool intel_detect_acpi_rst(void)
+{
+	if (bus_for_each_dev(&acpi_bus_type, NULL, NULL, match_device))
+		return true;;
+
+	return false;
+}
-- 
1.9.1