[PATCH v6 29/30] drm/xe/vf: Rebase CCS save/restore BB GGTT addresses

[Matthew Brost <matthew.brost@intel.com>]

Rebase the CCS save/restore BB's GGTT addresses during VF post-migration
recovery by setting the software ring tail to zero, the LRC ring head to
zero, and rewriting the jump-to-BB instructions.

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Satyanarayana K V P <satyanarayana.k.v.p@intel.com>
---
 drivers/gpu/drm/xe/xe_gt_sriov_vf.c  |  4 ++++
 drivers/gpu/drm/xe/xe_sriov_vf_ccs.c | 28 ++++++++++++++++++++++++++++
 drivers/gpu/drm/xe/xe_sriov_vf_ccs.h |  1 +
 3 files changed, 33 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_vf.c b/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
index d43e18bb8f01..fb4f848c2936 100644
--- a/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
+++ b/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
@@ -34,6 +34,7 @@
 #include "xe_pm.h"
 #include "xe_sriov.h"
 #include "xe_sriov_vf.h"
+#include "xe_sriov_vf_ccs.h"
 #include "xe_tile_sriov_vf.h"
 #include "xe_tlb_inval.h"
 #include "xe_uc_fw.h"
@@ -1153,6 +1154,9 @@ static int vf_post_migration_fixups(struct xe_gt *gt)
 	if (err)
 		return err;
 
+	if (xe_gt_is_main_type(gt))
+		xe_sriov_vf_ccs_rebase(gt_to_xe(gt));
+
 	xe_gt_sriov_vf_default_lrcs_hwsp_rebase(gt);
 	err = xe_guc_contexts_hwsp_rebase(&gt->uc.guc, buf);
 	if (err)
diff --git a/drivers/gpu/drm/xe/xe_sriov_vf_ccs.c b/drivers/gpu/drm/xe/xe_sriov_vf_ccs.c
index 8dec616c37c9..790249801364 100644
--- a/drivers/gpu/drm/xe/xe_sriov_vf_ccs.c
+++ b/drivers/gpu/drm/xe/xe_sriov_vf_ccs.c
@@ -175,6 +175,15 @@ static void ccs_rw_update_ring(struct xe_sriov_vf_ccs_ctx *ctx)
 	struct xe_lrc *lrc = xe_exec_queue_lrc(ctx->mig_q);
 	u32 dw[10], i = 0;
 
+	/*
+	 * XXX: Save/restore fixes — for some reason, the GuC only accepts the
+	 * save/restore context if the LRC head pointer is zero. This is evident
+	 * from repeated VF migrations failing when the LRC head pointer is
+	 * non-zero.
+	 */
+	lrc->ring.tail = 0;
+	xe_lrc_set_ring_head(lrc, 0);
+
 	dw[i++] = MI_ARB_ON_OFF | MI_ARB_ENABLE;
 	dw[i++] = MI_BATCH_BUFFER_START | XE_INSTR_NUM_DW(3);
 	dw[i++] = lower_32_bits(addr);
@@ -186,6 +195,25 @@ static void ccs_rw_update_ring(struct xe_sriov_vf_ccs_ctx *ctx)
 	xe_lrc_set_ring_tail(lrc, lrc->ring.tail);
 }
 
+/**
+ * xe_sriov_vf_ccs_rebase - Rebase GGTT addresses for CCS save / restore
+ * @xe: the &xe_device.
+ */
+void xe_sriov_vf_ccs_rebase(struct xe_device *xe)
+{
+	enum xe_sriov_vf_ccs_rw_ctxs ctx_id;
+
+	if (!IS_VF_CCS_READY(xe))
+		return;
+
+	for_each_ccs_rw_ctx(ctx_id) {
+		struct xe_sriov_vf_ccs_ctx *ctx =
+			&xe->sriov.vf.ccs.contexts[ctx_id];
+
+		ccs_rw_update_ring(ctx);
+	}
+}
+
 static int register_save_restore_context(struct xe_sriov_vf_ccs_ctx *ctx)
 {
 	int ctx_type;
diff --git a/drivers/gpu/drm/xe/xe_sriov_vf_ccs.h b/drivers/gpu/drm/xe/xe_sriov_vf_ccs.h
index 0745c0ff0228..f8ca6efce9ee 100644
--- a/drivers/gpu/drm/xe/xe_sriov_vf_ccs.h
+++ b/drivers/gpu/drm/xe/xe_sriov_vf_ccs.h
@@ -18,6 +18,7 @@ int xe_sriov_vf_ccs_init(struct xe_device *xe);
 int xe_sriov_vf_ccs_attach_bo(struct xe_bo *bo);
 int xe_sriov_vf_ccs_detach_bo(struct xe_bo *bo);
 int xe_sriov_vf_ccs_register_context(struct xe_device *xe);
+void xe_sriov_vf_ccs_rebase(struct xe_device *xe);
 void xe_sriov_vf_ccs_print(struct xe_device *xe, struct drm_printer *p);
 
 static inline bool xe_sriov_vf_ccs_ready(struct xe_device *xe)
-- 
2.34.1