anv: Disable constant buffer 0 being relative.

If we are on gen8+ and have context isolation support, just make that
constant buffer address be absolute, so we can use it for push UBOs too.

v2: Do not duplicate constant_buffer_0_is_relative flag (Jason)

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/intel/vulkan/anv_device.c

@@ -430,7 +430,8 @@ anv_physical_device_init(struct anv_physical_device *device,
    device->compiler->shader_debug_log = compiler_debug_log;
    device->compiler->shader_perf_log = compiler_perf_log;
    device->compiler->supports_pull_constants = false;
-   device->compiler->constant_buffer_0_is_relative = true;
+   device->compiler->constant_buffer_0_is_relative =
+      device->info.gen < 8 || !device->has_context_isolation;
 
    isl_device_init(&device->isl_dev, &device->info, swizzled);
 

src/intel/vulkan/genX_state.c

@@ -169,6 +169,33 @@ genX(init_device_state)(struct anv_device *device)
    gen10_emit_wa_lri_to_cache_mode_zero(&batch);
 #endif
 
+   /* Set the "CONSTANT_BUFFER Address Offset Disable" bit, so
+    * 3DSTATE_CONSTANT_XS buffer 0 is an absolute address.
+    *
+    * This is only safe on kernels with context isolation support.
+    */
+   if (GEN_GEN >= 8 &&
+       device->instance->physicalDevice.has_context_isolation) {
+      UNUSED uint32_t tmp_reg;
+#if GEN_GEN >= 9
+      anv_pack_struct(&tmp_reg, GENX(CS_DEBUG_MODE2),
+                      .CONSTANT_BUFFERAddressOffsetDisable = true,
+                      .CONSTANT_BUFFERAddressOffsetDisableMask = true);
+      anv_batch_emit(&batch, GENX(MI_LOAD_REGISTER_IMM), lri) {
+         lri.RegisterOffset = GENX(CS_DEBUG_MODE2_num);
+         lri.DataDWord      = tmp_reg;
+      }
+#elif GEN_GEN == 8
+      anv_pack_struct(&tmp_reg, GENX(INSTPM),
+                      .CONSTANT_BUFFERAddressOffsetDisable = true,
+                      .CONSTANT_BUFFERAddressOffsetDisableMask = true);
+      anv_batch_emit(&batch, GENX(MI_LOAD_REGISTER_IMM), lri) {
+         lri.RegisterOffset = GENX(INSTPM_num);
+         lri.DataDWord      = tmp_reg;
+      }
+#endif
+   }
+
    anv_batch_emit(&batch, GENX(MI_BATCH_BUFFER_END), bbe);
 
    assert(batch.next <= batch.end);