drm/i915/pxp: Create the arbitrary session after boot

Create the arbitrary session, with the fixed session id 0xf, after
system boot, for the case that application allocates the protected
buffer without establishing any protection session. Because the
hardware requires at least one alive session for protected buffer
creation.  This arbitrary session needs to be re-created after
teardown or power event because hardware encryption key won't be
valid after such cases.

Signed-off-by: Huang, Sean Z <sean.z.huang@intel.com>

drivers/gpu/drm/i915/Makefile

@@ -257,6 +257,7 @@ i915-y += i915_perf.o
 # Protected execution platform (PXP) support
 i915-$(CONFIG_DRM_I915_PXP) += \
 	pxp/intel_pxp.o \
+	pxp/intel_pxp_arb.o \
 	pxp/intel_pxp_context.o \
 	pxp/intel_pxp_tee.o
 

drivers/gpu/drm/i915/pxp/intel_pxp.c

@@ -6,6 +6,7 @@
 #include "intel_pxp.h"
 #include "intel_pxp_context.h"
 #include "intel_pxp_tee.h"
+#include "intel_pxp_arb.h"
 
 /* KCR register definitions */
 #define KCR_INIT            _MMIO(0x320f0)

drivers/gpu/drm/i915/pxp/intel_pxp.h

@@ -8,6 +8,22 @@
 
 #include "intel_pxp_context.h"
 
+enum pxp_session_types {
+	SESSION_TYPE_TYPE0 = 0,
+	SESSION_TYPE_TYPE1 = 1,
+
+	SESSION_TYPE_MAX
+};
+
+enum pxp_protection_modes {
+	PROTECTION_MODE_NONE = 0,
+	PROTECTION_MODE_LM   = 2,
+	PROTECTION_MODE_HM   = 3,
+	PROTECTION_MODE_SM   = 6,
+
+	PROTECTION_MODE_ALL
+};
+
 struct intel_pxp {
 	struct pxp_context ctx;
 };

drivers/gpu/drm/i915/pxp/intel_pxp_arb.c

@@ -0,0 +1,152 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright(c) 2020, Intel Corporation. All rights reserved.
+ */
+
+#include "gt/intel_context.h"
+#include "gt/intel_engine_pm.h"
+
+#include "intel_pxp_arb.h"
+#include "intel_pxp.h"
+#include "intel_pxp_context.h"
+#include "intel_pxp_tee.h"
+
+#define GEN12_KCR_SIP _MMIO(0x32260) /* KCR type0 session in play 0-31 */
+
+/* Arbitrary session */
+#define ARB_SESSION_INDEX 0xf
+#define ARB_SESSION_TYPE SESSION_TYPE_TYPE0
+#define ARB_PROTECTION_MODE PROTECTION_MODE_HM
+
+static bool is_hw_arb_session_in_play(struct intel_pxp *pxp)
+{
+	u32 regval_sip = 0;
+	intel_wakeref_t wakeref;
+	struct intel_gt *gt = container_of(pxp, struct intel_gt, pxp);
+
+	with_intel_runtime_pm(&gt->i915->runtime_pm, wakeref) {
+		regval_sip = intel_uncore_read(gt->uncore, GEN12_KCR_SIP);
+	}
+
+	return regval_sip & BIT(ARB_SESSION_INDEX);
+}
+
+/* wait hw session_in_play reg to match the current sw state */
+static int wait_arb_hw_sw_state(struct intel_pxp *pxp)
+{
+	const int max_retry = 10;
+	const int ms_delay = 10;
+	int retry = 0;
+	int ret;
+	struct pxp_protected_session *arb = pxp->ctx.arb_session;
+
+	ret = -EINVAL;
+	for (retry = 0; retry < max_retry; retry++) {
+		if (is_hw_arb_session_in_play(pxp) ==
+		    arb->is_in_play) {
+			ret = 0;
+			break;
+		}
+
+		msleep(ms_delay);
+	}
+
+	return ret;
+}
+
+/**
+ * create_session_entry - Create a new session entry with provided info.
+ * @pxp: pointer to pxp struct.
+ *
+ * Return: the pointer to the created session.
+ */
+static struct pxp_protected_session *create_session_entry(struct intel_pxp *pxp)
+{
+	struct pxp_protected_session *session;
+
+	session = kzalloc(sizeof(*session), GFP_KERNEL);
+	if (!session)
+		return NULL;
+
+	session->context_id = pxp->ctx.id;
+	session->type = ARB_SESSION_TYPE;
+	session->protection_mode = ARB_PROTECTION_MODE;
+	session->index = ARB_SESSION_INDEX;
+	session->is_in_play = false;
+
+	return session;
+}
+
+int intel_pxp_arb_reserve_session(struct intel_pxp *pxp)
+{
+	int ret;
+	struct pxp_protected_session *session = NULL;
+
+	lockdep_assert_held(&pxp->ctx.mutex);
+
+	ret = wait_arb_hw_sw_state(pxp);
+	if (ret)
+		return ret;
+
+	session = create_session_entry(pxp);
+	if (!session)
+		return -ENOMEM;
+
+	return ret;
+}
+
+/**
+ * intel_pxp_arb_mark_session_in_play - To put an reserved protected session to "in_play" state
+ * @pxp: pointer to pxp struct.
+ *
+ * Return: status. 0 means update is successful.
+ */
+static int intel_pxp_arb_mark_session_in_play(struct intel_pxp *pxp)
+{
+	struct pxp_protected_session *arb = pxp->ctx.arb_session;
+
+	lockdep_assert_held(&pxp->ctx.mutex);
+
+	if (arb->is_in_play)
+		return -EINVAL;
+
+	arb->is_in_play = true;
+	return 0;
+}
+
+int intel_pxp_arb_create_session(struct intel_pxp *pxp)
+{
+	int ret;
+	struct intel_gt *gt = container_of(pxp, typeof(*gt), pxp);
+
+	lockdep_assert_held(&pxp->ctx.mutex);
+
+	if (pxp->ctx.flag_display_hm_surface_keys) {
+		drm_err(&gt->i915->drm, "%s: arb session is alive so skipping the creation\n",
+			__func__);
+		return 0;
+	}
+
+	ret = intel_pxp_arb_reserve_session(pxp);
+	if (ret) {
+		drm_err(&gt->i915->drm, "Failed to reserve arb session\n");
+		goto end;
+	}
+
+	ret = intel_pxp_tee_cmd_create_arb_session(pxp);
+	if (ret) {
+		drm_err(&gt->i915->drm, "Failed to send tee cmd for arb session creation\n");
+		goto end;
+	}
+
+	ret = intel_pxp_arb_mark_session_in_play(pxp);
+	if (ret) {
+		drm_err(&gt->i915->drm, "Failed to mark arb session status in play\n");
+		goto end;
+	}
+
+	pxp->ctx.flag_display_hm_surface_keys = true;
+
+end:
+	return ret;
+}

drivers/gpu/drm/i915/pxp/intel_pxp_arb.h

@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright(c) 2020, Intel Corporation. All rights reserved.
+ */
+
+#ifndef __INTEL_PXP_SM_H__
+#define __INTEL_PXP_SM_H__
+
+#include "intel_pxp.h"
+
+/**
+ * struct pxp_protected_session - structure to track all active sessions.
+ */
+struct pxp_protected_session {
+	/** @index: Numeric identifier for this protected session */
+	int index;
+	/** @type: Type of session */
+	int type;
+	/** @protection_mode: mode of protection requested */
+	int protection_mode;
+	/** @context_id: context identifier of the protected session requestor */
+	int context_id;
+
+	/**
+	 * @is_in_play: indicates whether the session has been established
+	 *              in the HW root of trust if this flag is false, it
+	 *              indicates an application has reserved this session,
+	 *              but has not * established the session in the
+	 *              hardware yet.
+	 */
+	bool is_in_play;
+};
+
+int intel_pxp_arb_create_session(struct intel_pxp *pxp);
+
+#endif /* __INTEL_PXP_SM_H__ */

drivers/gpu/drm/i915/pxp/intel_pxp_context.h

@@ -13,7 +13,12 @@ struct pxp_context {
 	/** @mutex: mutex to protect the pxp context */
 	struct mutex mutex;
 
+	void *arb_session;
+	u32 arb_session_pxp_tag;
+
 	int id;
+
+	bool flag_display_hm_surface_keys;
 };
 
 void intel_pxp_ctx_init(struct pxp_context *ctx);

drivers/gpu/drm/i915/pxp/intel_pxp_tee.c

@@ -10,6 +10,7 @@
 #include "intel_pxp.h"
 #include "intel_pxp_context.h"
 #include "intel_pxp_tee.h"
+#include "intel_pxp_arb.h"
 
 static int intel_pxp_tee_io_message(struct intel_pxp *pxp,
 				    void *msg_in, u32 msg_in_size,
@@ -70,7 +71,9 @@ static int intel_pxp_tee_io_message(struct intel_pxp *pxp,
 static int i915_pxp_tee_component_bind(struct device *i915_kdev,
 				       struct device *tee_kdev, void *data)
 {
+	int ret;
 	struct drm_i915_private *i915 = kdev_to_i915(i915_kdev);
+	struct intel_pxp *pxp = &i915->gt.pxp;
 
 	if (!i915 || !tee_kdev || !data)
 		return -EPERM;
@@ -80,6 +83,16 @@ static int i915_pxp_tee_component_bind(struct device *i915_kdev,
 	i915->pxp_tee_master->tee_dev = tee_kdev;
 	mutex_unlock(&i915->pxp_tee_comp_mutex);
 
+	mutex_lock(&pxp->ctx.mutex);
+	/* Create arb session only if tee is ready, during system boot or sleep/resume */
+	ret = intel_pxp_arb_create_session(pxp);
+	mutex_unlock(&pxp->ctx.mutex);
+
+	if (ret) {
+		drm_err(&i915->drm, "Failed to create arb session ret=[%d]\n", ret);
+		return ret;
+	}
+
 	return 0;
 }
 
@@ -130,3 +143,28 @@ void intel_pxp_tee_component_fini(struct intel_pxp *pxp)
 
 	component_del(i915->drm.dev, &i915_pxp_tee_component_ops);
 }
+
+int intel_pxp_tee_cmd_create_arb_session(struct intel_pxp *pxp)
+{
+	int ret;
+	u32 msg_out_size_received = 0;
+	u32 msg_in[PXP_TEE_ARB_CMD_DW_LEN] = PXP_TEE_ARB_CMD_BIN;
+	u32 msg_out[PXP_TEE_ARB_CMD_DW_LEN] = {0};
+	struct intel_gt *gt = container_of(pxp, typeof(*gt), pxp);
+	struct drm_i915_private *i915 = gt->i915;
+
+	mutex_lock(&i915->pxp_tee_comp_mutex);
+
+	ret = intel_pxp_tee_io_message(pxp,
+				       &msg_in,
+				       sizeof(msg_in),
+				       &msg_out, &msg_out_size_received,
+				       sizeof(msg_out));
+
+	mutex_unlock(&i915->pxp_tee_comp_mutex);
+
+	if (ret)
+		drm_err(&i915->drm, "Failed to send/receive tee message\n");
+
+	return ret;
+}

drivers/gpu/drm/i915/pxp/intel_pxp_tee.h

@@ -11,4 +11,15 @@
 void intel_pxp_tee_component_init(struct intel_pxp *pxp);
 void intel_pxp_tee_component_fini(struct intel_pxp *pxp);
 
+int pxp_tee_ioctl_io_message(struct intel_pxp *pxp,
+			     void __user *msg_in_user_ptr, u32 msg_in_size,
+			     void __user *msg_out_user_ptr, u32 *msg_out_size_ptr,
+			     u32 msg_out_buf_size);
+
+int intel_pxp_tee_cmd_create_arb_session(struct intel_pxp *pxp);
+
+/* TEE command to create the arbitrary session */
+#define PXP_TEE_ARB_CMD_BIN {0x00040000, 0x0000001e, 0x00000000, 0x00000008, 0x00000002, 0x0000000f}
+#define PXP_TEE_ARB_CMD_DW_LEN (6)
+
 #endif /* __INTEL_PXP_TEE_H__ */