}
 
 static void i915_dump_lrc_obj(struct seq_file *m,
-                             struct intel_engine_cs *ring,
-                             struct drm_i915_gem_object *ctx_obj)
+                             struct intel_context *ctx,
+                             struct intel_engine_cs *ring)
 {
        struct page *page;
        uint32_t *reg_state;
        int j;
+       struct drm_i915_gem_object *ctx_obj = ctx->engine[ring->id].state;
        unsigned long ggtt_offset = 0;
 
        if (ctx_obj == NULL) {
        }
 
        seq_printf(m, "CONTEXT: %s %u\n", ring->name,
-                  intel_execlists_ctx_id(ctx_obj));
+                  intel_execlists_ctx_id(ctx, ring));
 
        if (!i915_gem_obj_ggtt_bound(ctx_obj))
                seq_puts(m, "\tNot bound in GGTT\n");
        list_for_each_entry(ctx, &dev_priv->context_list, link) {
                for_each_ring(ring, dev_priv, i) {
                        if (ring->default_context != ctx)
-                               i915_dump_lrc_obj(m, ring,
-                                                 ctx->engine[i].state);
+                               i915_dump_lrc_obj(m, ctx, ring);
                }
        }
 
 
                seq_printf(m, "\t%d requests in queue\n", count);
                if (head_req) {
-                       struct drm_i915_gem_object *ctx_obj;
-
-                       ctx_obj = head_req->ctx->engine[ring_id].state;
                        seq_printf(m, "\tHead request id: %u\n",
-                                  intel_execlists_ctx_id(ctx_obj));
+                                  intel_execlists_ctx_id(head_req->ctx, ring));
                        seq_printf(m, "\tHead request tail: %u\n",
                                   head_req->tail);
                }
 
        return 0;
 }
 
+static void
+logical_ring_init_platform_invariants(struct intel_engine_cs *ring)
+{
+       struct drm_device *dev = ring->dev;
+
+       ring->disable_lite_restore_wa = (IS_SKL_REVID(dev, 0, SKL_REVID_B0) ||
+                                       IS_BXT_REVID(dev, 0, BXT_REVID_A1)) &&
+                                       (ring->id == VCS || ring->id == VCS2);
+
+       ring->ctx_desc_template = GEN8_CTX_VALID;
+       ring->ctx_desc_template |= GEN8_CTX_ADDRESSING_MODE(dev) <<
+                                  GEN8_CTX_ADDRESSING_MODE_SHIFT;
+       if (IS_GEN8(dev))
+               ring->ctx_desc_template |= GEN8_CTX_L3LLC_COHERENT;
+       ring->ctx_desc_template |= GEN8_CTX_PRIVILEGE;
+
+       /* TODO: WaDisableLiteRestore when we start using semaphore
+        * signalling between Command Streamers */
+       /* ring->ctx_desc_template |= GEN8_CTX_FORCE_RESTORE; */
+
+       /* WaEnableForceRestoreInCtxtDescForVCS:skl */
+       /* WaEnableForceRestoreInCtxtDescForVCS:bxt */
+       if (ring->disable_lite_restore_wa)
+               ring->ctx_desc_template |= GEN8_CTX_FORCE_RESTORE;
+}
+
 /**
- * intel_execlists_ctx_id() - get the Execlists Context ID
- * @ctx_obj: Logical Ring Context backing object.
+ * intel_lr_context_descriptor_update() - calculate & cache the descriptor
+ *                                       descriptor for a pinned context
  *
- * Do not confuse with ctx->id! Unfortunately we have a name overload
- * here: the old context ID we pass to userspace as a handler so that
- * they can refer to a context, and the new context ID we pass to the
- * ELSP so that the GPU can inform us of the context status via
- * interrupts.
+ * @ctx: Context to work on
+ * @ring: Engine the descriptor will be used with
  *
- * Return: 20-bits globally unique context ID.
+ * The context descriptor encodes various attributes of a context,
+ * including its GTT address and some flags. Because it's fairly
+ * expensive to calculate, we'll just do it once and cache the result,
+ * which remains valid until the context is unpinned.
+ *
+ * This is what a descriptor looks like, from LSB to MSB:
+ *    bits 0-11:    flags, GEN8_CTX_* (cached in ctx_desc_template)
+ *    bits 12-31:    LRCA, GTT address of (the HWSP of) this context
+ *    bits 32-51:    ctx ID, a globally unique tag (the LRCA again!)
+ *    bits 52-63:    reserved, may encode the engine ID (for GuC)
  */
-u32 intel_execlists_ctx_id(struct drm_i915_gem_object *ctx_obj)
+static void
+intel_lr_context_descriptor_update(struct intel_context *ctx,
+                                  struct intel_engine_cs *ring)
 {
-       u32 lrca = i915_gem_obj_ggtt_offset(ctx_obj) +
-                       LRC_PPHWSP_PN * PAGE_SIZE;
+       uint64_t lrca, desc;
 
-       /* LRCA is required to be 4K aligned so the more significant 20 bits
-        * are globally unique */
-       return lrca >> 12;
-}
+       lrca = ctx->engine[ring->id].lrc_vma->node.start +
+              LRC_PPHWSP_PN * PAGE_SIZE;
 
-static bool disable_lite_restore_wa(struct intel_engine_cs *ring)
-{
-       struct drm_device *dev = ring->dev;
+       desc = ring->ctx_desc_template;                    /* bits  0-11 */
+       desc |= lrca;                                      /* bits 12-31 */
+       desc |= (lrca >> PAGE_SHIFT) << GEN8_CTX_ID_SHIFT; /* bits 32-51 */
 
-       return (IS_SKL_REVID(dev, 0, SKL_REVID_B0) ||
-               IS_BXT_REVID(dev, 0, BXT_REVID_A1)) &&
-              (ring->id == VCS || ring->id == VCS2);
+       ctx->engine[ring->id].lrc_desc = desc;
 }
 
 uint64_t intel_lr_context_descriptor(struct intel_context *ctx,
                                     struct intel_engine_cs *ring)
 {
-       struct drm_i915_gem_object *ctx_obj = ctx->engine[ring->id].state;
-       uint64_t desc;
-       uint64_t lrca = i915_gem_obj_ggtt_offset(ctx_obj) +
-                       LRC_PPHWSP_PN * PAGE_SIZE;
-
-       WARN_ON(lrca & 0xFFFFFFFF00000FFFULL);
-
-       desc = GEN8_CTX_VALID;
-       desc |= GEN8_CTX_ADDRESSING_MODE(dev) << GEN8_CTX_ADDRESSING_MODE_SHIFT;
-       if (IS_GEN8(ctx_obj->base.dev))
-               desc |= GEN8_CTX_L3LLC_COHERENT;
-       desc |= GEN8_CTX_PRIVILEGE;
-       desc |= lrca;
-       desc |= (u64)intel_execlists_ctx_id(ctx_obj) << GEN8_CTX_ID_SHIFT;
-
-       /* TODO: WaDisableLiteRestore when we start using semaphore
-        * signalling between Command Streamers */
-       /* desc |= GEN8_CTX_FORCE_RESTORE; */
-
-       /* WaEnableForceRestoreInCtxtDescForVCS:skl */
-       /* WaEnableForceRestoreInCtxtDescForVCS:bxt */
-       if (disable_lite_restore_wa(ring))
-               desc |= GEN8_CTX_FORCE_RESTORE;
+       return ctx->engine[ring->id].lrc_desc;
+}
 
-       return desc;
+/**
+ * intel_execlists_ctx_id() - get the Execlists Context ID
+ * @ctx: Context to get the ID for
+ * @ring: Engine to get the ID for
+ *
+ * Do not confuse with ctx->id! Unfortunately we have a name overload
+ * here: the old context ID we pass to userspace as a handler so that
+ * they can refer to a context, and the new context ID we pass to the
+ * ELSP so that the GPU can inform us of the context status via
+ * interrupts.
+ *
+ * The context ID is a portion of the context descriptor, so we can
+ * just extract the required part from the cached descriptor.
+ *
+ * Return: 20-bits globally unique context ID.
+ */
+u32 intel_execlists_ctx_id(struct intel_context *ctx,
+                          struct intel_engine_cs *ring)
+{
+       return intel_lr_context_descriptor(ctx, ring) >> GEN8_CTX_ID_SHIFT;
 }
 
 static void execlists_elsp_write(struct drm_i915_gem_request *rq0,
        uint32_t *reg_state;
 
        BUG_ON(!ctx_obj);
-       WARN_ON(!i915_gem_obj_is_pinned(ctx_obj));
-       WARN_ON(!i915_gem_obj_is_pinned(rb_obj));
 
        page = i915_gem_object_get_dirty_page(ctx_obj, LRC_STATE_PN);
        reg_state = kmap_atomic(page);
                                            execlist_link);
 
        if (head_req != NULL) {
-               struct drm_i915_gem_object *ctx_obj =
-                               head_req->ctx->engine[ring->id].state;
-               if (intel_execlists_ctx_id(ctx_obj) == request_id) {
+               if (intel_execlists_ctx_id(head_req->ctx, ring) == request_id) {
                        WARN(head_req->elsp_submitted == 0,
                             "Never submitted head request\n");
 
                }
        }
 
-       if (disable_lite_restore_wa(ring)) {
+       if (ring->disable_lite_restore_wa) {
                /* Prevent a ctx to preempt itself */
                if ((status & GEN8_CTX_STATUS_ACTIVE_IDLE) &&
                    (submit_contexts != 0))
 }
 
 static int intel_lr_context_do_pin(struct intel_engine_cs *ring,
-               struct drm_i915_gem_object *ctx_obj,
-               struct intel_ringbuffer *ringbuf)
+                                  struct intel_context *ctx)
 {
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
-       int ret = 0;
+       struct drm_i915_gem_object *ctx_obj = ctx->engine[ring->id].state;
+       struct intel_ringbuffer *ringbuf = ctx->engine[ring->id].ringbuf;
+       int ret;
 
        WARN_ON(!mutex_is_locked(&ring->dev->struct_mutex));
+
        ret = i915_gem_obj_ggtt_pin(ctx_obj, GEN8_LR_CONTEXT_ALIGN,
                        PIN_OFFSET_BIAS | GUC_WOPCM_TOP);
        if (ret)
        if (ret)
                goto unpin_ctx_obj;
 
+       ctx->engine[ring->id].lrc_vma = i915_gem_obj_to_ggtt(ctx_obj);
+       intel_lr_context_descriptor_update(ctx, ring);
        ctx_obj->dirty = true;
 
        /* Invalidate GuC TLB. */
 {
        int ret = 0;
        struct intel_engine_cs *ring = rq->ring;
-       struct drm_i915_gem_object *ctx_obj = rq->ctx->engine[ring->id].state;
-       struct intel_ringbuffer *ringbuf = rq->ringbuf;
 
        if (rq->ctx->engine[ring->id].pin_count++ == 0) {
-               ret = intel_lr_context_do_pin(ring, ctx_obj, ringbuf);
+               ret = intel_lr_context_do_pin(ring, rq->ctx);
                if (ret)
                        goto reset_pin_count;
        }
                if (--rq->ctx->engine[ring->id].pin_count == 0) {
                        intel_unpin_ringbuffer_obj(ringbuf);
                        i915_gem_object_ggtt_unpin(ctx_obj);
+                       rq->ctx->engine[ring->id].lrc_vma = NULL;
+                       rq->ctx->engine[ring->id].lrc_desc = 0;
                }
        }
 }
                ring->status_page.obj = NULL;
        }
 
+       ring->disable_lite_restore_wa = false;
+       ring->ctx_desc_template = 0;
+
        lrc_destroy_wa_ctx_obj(ring);
        ring->dev = NULL;
 }
        INIT_LIST_HEAD(&ring->execlist_retired_req_list);
        spin_lock_init(&ring->execlist_lock);
 
+       logical_ring_init_platform_invariants(ring);
+
        ret = i915_cmd_parser_init_ring(ring);
        if (ret)
                goto error;
                goto error;
 
        /* As this is the default context, always pin it */
-       ret = intel_lr_context_do_pin(
-                       ring,
-                       ring->default_context->engine[ring->id].state,
-                       ring->default_context->engine[ring->id].ringbuf);
+       ret = intel_lr_context_do_pin(ring, ring->default_context);
        if (ret) {
                DRM_ERROR(
                        "Failed to pin and map ringbuffer %s: %d\n",