drm/i915/gvt: scan VM ctx pages

Logical Context is actually a big batch buffer consisting of multiple
LRI commands + saved registers. It comprises Ring Context (the first
0x50 dwords) and Engine Context. The registers defined in Engine Context
are command accessible, and safe to execute in VM Context.
This patch
1. stops copy Ring Context and only copys Engine Context from VM Context
2. audits VM Engine Contexts to disallow undesired LRIs
(if accessing registers out of Engine Context that hardware generates).

Cc: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Wang Zhi <zhi.a.wang@intel.com>
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20201223034500.16983-1-yan.y.zhao@intel.comReviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>

drivers/gpu/drm/i915/gvt/cmd_parser.c

@@ -3193,6 +3193,58 @@ void intel_gvt_update_reg_whitelist(struct intel_vgpu *vgpu)
 	}
 }
 
+int intel_gvt_scan_engine_context(struct intel_vgpu_workload *workload)
+{
+	struct intel_vgpu *vgpu = workload->vgpu;
+	unsigned long gma_head, gma_tail, gma_start, ctx_size;
+	struct parser_exec_state s;
+	int ring_id = workload->engine->id;
+	struct intel_context *ce = vgpu->submission.shadow[ring_id];
+	int ret;
+
+	GEM_BUG_ON(atomic_read(&ce->pin_count) < 0);
+
+	ctx_size = workload->engine->context_size - PAGE_SIZE;
+
+	/* Only ring contxt is loaded to HW for inhibit context, no need to
+	 * scan engine context
+	 */
+	if (is_inhibit_context(ce))
+		return 0;
+
+	gma_start = i915_ggtt_offset(ce->state) + LRC_STATE_PN*PAGE_SIZE;
+	gma_head = 0;
+	gma_tail = ctx_size;
+
+	s.buf_type = RING_BUFFER_CTX;
+	s.buf_addr_type = GTT_BUFFER;
+	s.vgpu = workload->vgpu;
+	s.engine = workload->engine;
+	s.ring_start = gma_start;
+	s.ring_size = ctx_size;
+	s.ring_head = gma_start + gma_head;
+	s.ring_tail = gma_start + gma_tail;
+	s.rb_va = ce->lrc_reg_state;
+	s.workload = workload;
+	s.is_ctx_wa = false;
+	s.is_init_ctx = false;
+
+	/* don't scan the first RING_CTX_SIZE(0x50) dwords, as it's ring
+	 * context
+	 */
+	ret = ip_gma_set(&s, gma_start + gma_head + RING_CTX_SIZE);
+	if (ret)
+		goto out;
+
+	ret = command_scan(&s, gma_head, gma_tail,
+		gma_start, ctx_size);
+out:
+	if (ret)
+		gvt_vgpu_err("scan shadow ctx error\n");
+
+	return ret;
+}
+
 static int init_cmd_table(struct intel_gvt *gvt)
 {
 	unsigned int gen_type = intel_gvt_get_device_type(gvt);

drivers/gpu/drm/i915/gvt/cmd_parser.h

@@ -52,4 +52,6 @@ int intel_gvt_scan_and_shadow_wa_ctx(struct intel_shadow_wa_ctx *wa_ctx);
 
 void intel_gvt_update_reg_whitelist(struct intel_vgpu *vgpu);
 
+int intel_gvt_scan_engine_context(struct intel_vgpu_workload *workload);
+
 #endif

drivers/gpu/drm/i915/gvt/reg.h

@@ -133,4 +133,6 @@
 #define RING_GFX_MODE(base)	_MMIO((base) + 0x29c)
 #define VF_GUARDBAND		_MMIO(0x83a4)
 
+
+#define BCS_TILE_REGISTER_VAL_OFFSET (0x43*4)
 #endif

drivers/gpu/drm/i915/gvt/scheduler.c

@@ -137,6 +137,7 @@ static int populate_shadow_context(struct intel_vgpu_workload *workload)
 	int i;
 	bool skip = false;
 	int ring_id = workload->engine->id;
+	int ret;
 
 	GEM_BUG_ON(!intel_context_is_pinned(ctx));
 
@@ -163,16 +164,24 @@ static int populate_shadow_context(struct intel_vgpu_workload *workload)
 		COPY_REG(bb_per_ctx_ptr);
 		COPY_REG(rcs_indirect_ctx);
 		COPY_REG(rcs_indirect_ctx_offset);
-	}
+	} else if (workload->engine->id == BCS0)
+		intel_gvt_hypervisor_read_gpa(vgpu,
+				workload->ring_context_gpa +
+				BCS_TILE_REGISTER_VAL_OFFSET,
+				(void *)shadow_ring_context +
+				BCS_TILE_REGISTER_VAL_OFFSET, 4);
 #undef COPY_REG
 #undef COPY_REG_MASKED
 
+	/* don't copy Ring Context (the first 0x50 dwords),
+	 * only copy the Engine Context part from guest
+	 */
 	intel_gvt_hypervisor_read_gpa(vgpu,
 			workload->ring_context_gpa +
-			sizeof(*shadow_ring_context),
+			RING_CTX_SIZE,
 			(void *)shadow_ring_context +
-			sizeof(*shadow_ring_context),
-			I915_GTT_PAGE_SIZE - sizeof(*shadow_ring_context));
+			RING_CTX_SIZE,
+			I915_GTT_PAGE_SIZE - RING_CTX_SIZE);
 
 	sr_oa_regs(workload, (u32 *)shadow_ring_context, false);
 
@@ -239,6 +248,11 @@ static int populate_shadow_context(struct intel_vgpu_workload *workload)
 		gpa_size = I915_GTT_PAGE_SIZE;
 		dst = context_base + (i << I915_GTT_PAGE_SHIFT);
 	}
+	ret = intel_gvt_scan_engine_context(workload);
+	if (ret) {
+		gvt_vgpu_err("invalid cmd found in guest context pages\n");
+		return ret;
+	}
 	s->last_ctx[ring_id].valid = true;
 	return 0;
 }