drm/xe/lrc: Prepare WA BB setup for more users

The post context restore (WA BB) is a mechanism in HW that may be used
for things other than the utilization setup. Create a new function
called setup_wa_bb() that wraps any function writing useful commands in
the buffer.

Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Link: https://lore.kernel.org/r/20250604-wa-bb-fix-v1-2-0dfc5dafcef0@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

diff --git a/drivers/gpu/drm/xe/xe_lrc.c b/drivers/gpu/drm/xe/xe_lrc.c
index bf7c3981897def4dfee84c8d2ad91035ec9de5f0..529c6a972a55bd57b5c5dd3116213e2a675572d9 100644 (file)
--- a/drivers/gpu/drm/xe/xe_lrc.c
+++ b/drivers/gpu/drm/xe/xe_lrc.c
@@ -914,9 +914,8 @@ static void xe_lrc_finish(struct xe_lrc *lrc)
 }
 
 /*
- * xe_lrc_setup_utilization() - Setup wa bb to assist in calculating active
- * context run ticks.
- * @lrc: Pointer to the lrc.
+ * wa_bb_setup_utilization() - Write commands to wa bb to assist
+ * in calculating active context run ticks.
  *
  * Context Timestamp (CTX_TIMESTAMP) in the LRC accumulates the run ticks of the
  * context, but only gets updated when the context switches out. In order to
@@ -941,18 +940,13 @@ static void xe_lrc_finish(struct xe_lrc *lrc)
  * store it in the PPHSWP.
  */
 #define CONTEXT_ACTIVE 1ULL
-static int xe_lrc_setup_utilization(struct xe_lrc *lrc)
+static ssize_t wa_bb_setup_utilization(struct xe_lrc *lrc, struct xe_hw_engine *hwe,
+                                      u32 *batch, size_t max_len)
 {
-       u32 *cmd, *buf = NULL;
+       u32 *cmd = batch;
 
-       if (lrc->bb_per_ctx_bo->vmap.is_iomem) {
-               buf = kmalloc(lrc->bb_per_ctx_bo->size, GFP_KERNEL);
-               if (!buf)
-                       return -ENOMEM;
-               cmd = buf;
-       } else {
-               cmd = lrc->bb_per_ctx_bo->vmap.vaddr;
-       }
+       if (xe_gt_WARN_ON(lrc->gt, max_len < 12))
+               return -ENOSPC;
 
        *cmd++ = MI_STORE_REGISTER_MEM | MI_SRM_USE_GGTT | MI_SRM_ADD_CS_OFFSET;
        *cmd++ = ENGINE_ID(0).addr;
@@ -971,6 +965,49 @@ static int xe_lrc_setup_utilization(struct xe_lrc *lrc)
                *cmd++ = upper_32_bits(CONTEXT_ACTIVE);
        }
 
+       return cmd - batch;
+}
+
+struct wa_bb_setup {
+       ssize_t (*setup)(struct xe_lrc *lrc, struct xe_hw_engine *hwe,
+                        u32 *batch, size_t max_size);
+};
+
+static int setup_wa_bb(struct xe_lrc *lrc, struct xe_hw_engine *hwe)
+{
+       const size_t max_size = lrc->bb_per_ctx_bo->size;
+       static const struct wa_bb_setup funcs[] = {
+               { .setup = wa_bb_setup_utilization },
+       };
+       ssize_t remain;
+       u32 *cmd, *buf = NULL;
+
+       if (lrc->bb_per_ctx_bo->vmap.is_iomem) {
+               buf = kmalloc(max_size, GFP_KERNEL);
+               if (!buf)
+                       return -ENOMEM;
+               cmd = buf;
+       } else {
+               cmd = lrc->bb_per_ctx_bo->vmap.vaddr;
+       }
+
+       remain = max_size / sizeof(*cmd);
+
+       for (size_t i = 0; i < ARRAY_SIZE(funcs); i++) {
+               ssize_t len = funcs[i].setup(lrc, hwe, cmd, remain);
+
+               remain -= len;
+
+               /*
+                * There should always be at least 1 additional dword for
+                * the end marker
+                */
+               if (len < 0 || xe_gt_WARN_ON(lrc->gt, remain < 1))
+                       goto fail;
+
+               cmd += len;
+       }
+
        *cmd++ = MI_BATCH_BUFFER_END;
 
        if (buf) {
@@ -983,6 +1020,10 @@ static int xe_lrc_setup_utilization(struct xe_lrc *lrc)
                             xe_bo_ggtt_addr(lrc->bb_per_ctx_bo) | 1);
 
        return 0;
+
+fail:
+       kfree(buf);
+       return -ENOSPC;
 }
 
 #define PVC_CTX_ASID           (0x2e + 1)
@@ -1139,7 +1180,7 @@ static int xe_lrc_init(struct xe_lrc *lrc, struct xe_hw_engine *hwe,
        map = __xe_lrc_start_seqno_map(lrc);
        xe_map_write32(lrc_to_xe(lrc), &map, lrc->fence_ctx.next_seqno - 1);
 
-       err = xe_lrc_setup_utilization(lrc);
+       err = setup_wa_bb(lrc, hwe);
        if (err)
                goto err_lrc_finish;