i915/gvt: Save the initial HW state snapshot in i915

Save the initial HW state snapshot in i915 so that the rest code of GVT-g
can be moved into a dedicated module while it can still get a clean
initial HW state saved at the correct time during the initialization of
i915. The futhrer vGPU created by GVT-g will use this HW state as the
initial HW state.

v6:
- Remove the reference of intel_gvt_device_info.(Christoph)
- Refine the save_mmio() function. (Christoph)

Cc: Christoph Hellwig <hch@lst.de>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Vivi Rodrigo <rodrigo.vivi@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20220407071945.72148-3-zhi.a.wang@intel.com

drivers/gpu/drm/i915/i915_drv.h

@@ -432,6 +432,8 @@ struct i915_virtual_gpu {
 	struct mutex lock; /* serialises sending of g2v_notify command pkts */
 	bool active;
 	u32 caps;
+	u32 *initial_mmio;
+	u8 *initial_cfg_space;
 };
 
 struct i915_selftest_stash {

drivers/gpu/drm/i915/intel_gvt.c

@@ -86,6 +86,85 @@ void intel_gvt_sanitize_options(struct drm_i915_private *dev_priv)
 	dev_priv->params.enable_gvt = 0;
 }
 
+static void free_initial_hw_state(struct drm_i915_private *dev_priv)
+{
+	struct i915_virtual_gpu *vgpu = &dev_priv->vgpu;
+
+	vfree(vgpu->initial_mmio);
+	vgpu->initial_mmio = NULL;
+
+	kfree(vgpu->initial_cfg_space);
+	vgpu->initial_cfg_space = NULL;
+}
+
+static void save_mmio(struct intel_gvt_mmio_table_iter *iter, u32 offset,
+		      u32 size)
+{
+	struct drm_i915_private *dev_priv = iter->i915;
+	u32 *mmio, i;
+
+	for (i = offset; i < offset + size; i += 4) {
+		mmio = iter->data + i;
+		*mmio = intel_uncore_read_notrace(to_gt(dev_priv)->uncore,
+						  _MMIO(i));
+	}
+}
+
+static int handle_mmio(struct intel_gvt_mmio_table_iter *iter,
+		       u32 offset, u32 size)
+{
+	if (WARN_ON(!IS_ALIGNED(offset, 4)))
+		return -EINVAL;
+
+	save_mmio(iter, offset, size);
+	return 0;
+}
+
+static int save_initial_hw_state(struct drm_i915_private *dev_priv)
+{
+	struct pci_dev *pdev = to_pci_dev(dev_priv->drm.dev);
+	struct i915_virtual_gpu *vgpu = &dev_priv->vgpu;
+	struct intel_gvt_mmio_table_iter iter;
+	void *mem;
+	int i, ret;
+
+	mem = kzalloc(PCI_CFG_SPACE_EXP_SIZE, GFP_KERNEL);
+	if (!mem)
+		return -ENOMEM;
+
+	vgpu->initial_cfg_space = mem;
+
+	for (i = 0; i < PCI_CFG_SPACE_EXP_SIZE; i += 4)
+		pci_read_config_dword(pdev, i, mem + i);
+
+	mem = vzalloc(2 * SZ_1M);
+	if (!mem) {
+		ret = -ENOMEM;
+		goto err_mmio;
+	}
+
+	vgpu->initial_mmio = mem;
+
+	iter.i915 = dev_priv;
+	iter.data = vgpu->initial_mmio;
+	iter.handle_mmio_cb = handle_mmio;
+
+	ret = intel_gvt_iterate_mmio_table(&iter);
+	if (ret)
+		goto err_iterate;
+
+	return 0;
+
+err_iterate:
+	vfree(vgpu->initial_mmio);
+	vgpu->initial_mmio = NULL;
+err_mmio:
+	kfree(vgpu->initial_cfg_space);
+	vgpu->initial_cfg_space = NULL;
+
+	return ret;
+}
+
 /**
  * intel_gvt_init - initialize GVT components
  * @dev_priv: drm i915 private data
@@ -115,15 +194,23 @@ int intel_gvt_init(struct drm_i915_private *dev_priv)
 		return -EIO;
 	}
 
+	ret = save_initial_hw_state(dev_priv);
+	if (ret) {
+		drm_dbg(&dev_priv->drm, "Fail to save initial HW state\n");
+		goto err_save_hw_state;
+	}
+
 	ret = intel_gvt_init_device(dev_priv);
 	if (ret) {
 		drm_dbg(&dev_priv->drm, "Fail to init GVT device\n");
-		goto bail;
+		goto err_init_device;
 	}
 
 	return 0;
 
-bail:
+err_init_device:
+	free_initial_hw_state(dev_priv);
+err_save_hw_state:
 	dev_priv->params.enable_gvt = 0;
 	return 0;
 }
@@ -147,6 +234,7 @@ void intel_gvt_driver_remove(struct drm_i915_private *dev_priv)
 		return;
 
 	intel_gvt_clean_device(dev_priv);
+	free_initial_hw_state(dev_priv);
 }
 
 /**