drm/xe/pxp: Add GSC session initialization support

A session is initialized (i.e. started) by sending a message to the GSC.
The initialization will be triggered when a user opts-in to using PXP;
the interface for that is coming in a follow-up patch in the series.

v2: clean up error messages, use new ARB define (John)

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250129174140.948829-7-daniele.ceraolospurio@intel.com

Author: dceraolo

drivers/gpu/drm/xe/abi/gsc_pxp_commands_abi.h

@@ -51,6 +51,7 @@ struct pxp_cmd_header {
 } __packed;
 
 #define PXP43_CMDID_INVALIDATE_STREAM_KEY 0x00000007
+#define PXP43_CMDID_INIT_SESSION 0x00000036
 #define PXP43_CMDID_NEW_HUC_AUTH 0x0000003F /* MTL+ */
 
 /* PXP-Input-Packet: HUC Auth-only */
@@ -65,6 +66,26 @@ struct pxp43_huc_auth_out {
 	struct pxp_cmd_header header;
 } __packed;
 
+/* PXP-Input-Packet: Init PXP session */
+struct pxp43_create_arb_in {
+	struct pxp_cmd_header header;
+		/* header.stream_id fields for vesion 4.3 of Init PXP session: */
+		#define PXP43_INIT_SESSION_VALID BIT(0)
+		#define PXP43_INIT_SESSION_APPTYPE BIT(1)
+		#define PXP43_INIT_SESSION_APPID GENMASK(17, 2)
+	u32 protection_mode;
+		#define PXP43_INIT_SESSION_PROTECTION_ARB 0x2
+	u32 sub_session_id;
+	u32 init_flags;
+	u32 rsvd[12];
+} __packed;
+
+/* PXP-Input-Packet: Init PXP session */
+struct pxp43_create_arb_out {
+	struct pxp_cmd_header header;
+	u32 rsvd[8];
+} __packed;
+
 /* PXP-Input-Packet: Invalidate Stream Key */
 struct pxp43_inv_stream_key_in {
 	struct pxp_cmd_header header;

drivers/gpu/drm/xe/xe_pxp_submit.c

@@ -16,6 +16,7 @@
 #include "xe_gt.h"
 #include "xe_lrc.h"
 #include "xe_map.h"
+#include "xe_pxp.h"
 #include "xe_pxp_types.h"
 #include "xe_sched_job.h"
 #include "xe_vm.h"
@@ -490,6 +491,52 @@ static int gsccs_send_message(struct xe_pxp_gsc_client_resources *gsc_res,
 	return ret;
 }
 
+/**
+ * xe_pxp_submit_session_init - submits a PXP GSC session initialization
+ * @gsc_res: the pxp client resources
+ * @id: the session to initialize
+ *
+ * Submit a message to the GSC FW to initialize (i.e. start) a PXP session.
+ *
+ * Returns 0 if the submission is successful, an errno value otherwise.
+ */
+int xe_pxp_submit_session_init(struct xe_pxp_gsc_client_resources *gsc_res, u32 id)
+{
+	struct xe_device *xe = gsc_res->vm->xe;
+	struct pxp43_create_arb_in msg_in = {0};
+	struct pxp43_create_arb_out msg_out = {0};
+	int ret;
+
+	msg_in.header.api_version = PXP_APIVER(4, 3);
+	msg_in.header.command_id = PXP43_CMDID_INIT_SESSION;
+	msg_in.header.stream_id = (FIELD_PREP(PXP43_INIT_SESSION_APPID, id) |
+				   FIELD_PREP(PXP43_INIT_SESSION_VALID, 1) |
+				   FIELD_PREP(PXP43_INIT_SESSION_APPTYPE, 0));
+	msg_in.header.buffer_len = sizeof(msg_in) - sizeof(msg_in.header);
+
+	if (id == DRM_XE_PXP_HWDRM_DEFAULT_SESSION)
+		msg_in.protection_mode = PXP43_INIT_SESSION_PROTECTION_ARB;
+
+	ret = gsccs_send_message(gsc_res, &msg_in, sizeof(msg_in),
+				 &msg_out, sizeof(msg_out));
+	if (ret) {
+		drm_err(&xe->drm, "Failed to init PXP session %u (%pe)\n", id, ERR_PTR(ret));
+	} else if (msg_out.header.status != 0) {
+		ret = -EIO;
+
+		if (is_fw_err_platform_config(msg_out.header.status))
+			drm_info_once(&xe->drm,
+				      "Failed to init PXP session %u due to BIOS/SOC, s=0x%x(%s)\n",
+				      id, msg_out.header.status,
+				      fw_err_to_string(msg_out.header.status));
+		else
+			drm_dbg(&xe->drm, "Failed to init PXP session %u, s=0x%x\n",
+				id, msg_out.header.status);
+	}
+
+	return ret;
+}
+
 /**
  * xe_pxp_submit_session_invalidation - submits a PXP GSC invalidation
  * @gsc_res: the pxp client resources

drivers/gpu/drm/xe/xe_pxp_submit.h

@@ -14,6 +14,7 @@ struct xe_pxp_gsc_client_resources;
 int xe_pxp_allocate_execution_resources(struct xe_pxp *pxp);
 void xe_pxp_destroy_execution_resources(struct xe_pxp *pxp);
 
+int xe_pxp_submit_session_init(struct xe_pxp_gsc_client_resources *gsc_res, u32 id);
 int xe_pxp_submit_session_termination(struct xe_pxp *pxp, u32 id);
 int xe_pxp_submit_session_invalidation(struct xe_pxp_gsc_client_resources *gsc_res,
 				       u32 id);