drm/i915/pxp: Invalidate all PXP fw sessions during teardown

A gap was recently discovered where if an application did not
invalidate all of the stream keys (intentionally or not), and the
driver did a full PXP global teardown on the GT subsystem, we
find that future session creation would fail on the security
firmware's side of the equation. i915 is the entity that needs
ensure the sessions' state across both iGT and security firmware
are at a known clean point when performing a full global teardown.

Architecturally speaking, i915 should inspect all active sessions
and submit the invalidate-stream-key PXP command to the security
firmware for each of them. However, for the upstream i915 driver
we only support the arbitration session that can be created
so that will be the only session we will cleanup.
Signed-off-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Reviewed-by: Juston Li <justonli@chromium.org>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230125082637.118970-5-alan.previn.teres.alexis@intel.com

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

@@ -24,6 +24,7 @@ void intel_pxp_init_hw(struct intel_pxp *pxp);
 void intel_pxp_fini_hw(struct intel_pxp *pxp);
 
 void intel_pxp_mark_termination_in_progress(struct intel_pxp *pxp);
+void intel_pxp_tee_end_arb_fw_session(struct intel_pxp *pxp, u32 arb_session_id);
 
 int intel_pxp_start(struct intel_pxp *pxp);
 

drivers/gpu/drm/i915/pxp/intel_pxp_cmd_interface_42.h

@@ -12,6 +12,9 @@
 /* PXP-Opcode for Init Session */
 #define PXP42_CMDID_INIT_SESSION 0x1e
 
+/* PXP-Opcode for Invalidate Stream Key */
+#define PXP42_CMDID_INVALIDATE_STREAM_KEY 0x00000007
+
 /* PXP-Input-Packet: Init Session (Arb-Session) */
 struct pxp42_create_arb_in {
 	struct pxp_cmd_header header;
@@ -25,4 +28,16 @@ struct pxp42_create_arb_out {
 	struct pxp_cmd_header header;
 } __packed;
 
+/* PXP-Input-Packet: Invalidate Stream Key */
+struct pxp42_inv_stream_key_in {
+	struct pxp_cmd_header header;
+	u32 rsvd[3];
+} __packed;
+
+/* PXP-Output-Packet: Invalidate Stream Key */
+struct pxp42_inv_stream_key_out {
+	struct pxp_cmd_header header;
+	u32 rsvd;
+} __packed;
+
 #endif /* __INTEL_PXP_FW_INTERFACE_42_H__ */

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

@@ -28,6 +28,9 @@ struct pxp_cmd_header {
 	union {
 		u32 status; /* out */
 		u32 stream_id; /* in */
+#define PXP_CMDHDR_EXTDATA_SESSION_VALID GENMASK(0, 0)
+#define PXP_CMDHDR_EXTDATA_APP_TYPE GENMASK(1, 1)
+#define PXP_CMDHDR_EXTDATA_SESSION_ID GENMASK(17, 2)
 	};
 	/* Length of the message (excluding the header) */
 	u32 buffer_len;

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

@@ -110,6 +110,8 @@ static int pxp_terminate_arb_session_and_global(struct intel_pxp *pxp)
 
 	intel_uncore_write(gt->uncore, PXP_GLOBAL_TERMINATE, 1);
 
+	intel_pxp_tee_end_arb_fw_session(pxp, ARB_SESSION);
+
 	return ret;
 }
 

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

@@ -319,3 +319,38 @@ int intel_pxp_tee_cmd_create_arb_session(struct intel_pxp *pxp,
 
 	return ret;
 }
+
+void intel_pxp_tee_end_arb_fw_session(struct intel_pxp *pxp, u32 session_id)
+{
+	struct drm_i915_private *i915 = pxp->ctrl_gt->i915;
+	struct pxp42_inv_stream_key_in msg_in = {0};
+	struct pxp42_inv_stream_key_out msg_out = {0};
+	int ret, trials = 0;
+
+try_again:
+	memset(&msg_in, 0, sizeof(msg_in));
+	memset(&msg_out, 0, sizeof(msg_out));
+	msg_in.header.api_version = PXP_APIVER(4, 2);
+	msg_in.header.command_id = PXP42_CMDID_INVALIDATE_STREAM_KEY;
+	msg_in.header.buffer_len = sizeof(msg_in) - sizeof(msg_in.header);
+
+	msg_in.header.stream_id = FIELD_PREP(PXP_CMDHDR_EXTDATA_SESSION_VALID, 1);
+	msg_in.header.stream_id |= FIELD_PREP(PXP_CMDHDR_EXTDATA_APP_TYPE, 0);
+	msg_in.header.stream_id |= FIELD_PREP(PXP_CMDHDR_EXTDATA_SESSION_ID, session_id);
+
+	ret = intel_pxp_tee_io_message(pxp,
+				       &msg_in, sizeof(msg_in),
+				       &msg_out, sizeof(msg_out),
+				       NULL);
+
+	/* Cleanup coherency between GT and Firmware is critical, so try again if it fails */
+	if ((ret || msg_out.header.status != 0x0) && ++trials < 3)
+		goto try_again;
+
+	if (ret)
+		drm_err(&i915->drm, "Failed to send tee msg for inv-stream-key-%d, ret=[%d]\n",
+			session_id, ret);
+	else if (msg_out.header.status != 0x0)
+		drm_warn(&i915->drm, "PXP firmware failed inv-stream-key-%d with status 0x%08x\n",
+			 session_id, msg_out.header.status);
+}