drm/i915/gvt: enter failsafe mode when guest requires more resources

Windows guest will notitfy GVT-g to request more resources through g2v
interface, when its resources are not enough.
This patch is to handle this case and let vgpu enter failsafe mode to
avoid too many error messages.
Signed-off-by: Min He <min.he@intel.com>
Signed-off-by: Pei Zhang <pei.zhang@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

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

@@ -453,6 +453,7 @@ struct intel_gvt_ops {
 
 enum {
 	GVT_FAILSAFE_UNSUPPORTED_GUEST,
+	GVT_FAILSAFE_INSUFFICIENT_RESOURCE,
 };
 
 #include "mpt.h"

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

@@ -157,6 +157,8 @@ static void enter_failsafe_mode(struct intel_vgpu *vgpu, int reason)
 	case GVT_FAILSAFE_UNSUPPORTED_GUEST:
 		pr_err("Detected your guest driver doesn't support GVT-g.\n");
 		break;
+	case GVT_FAILSAFE_INSUFFICIENT_RESOURCE:
+		pr_err("Graphics resource is not enough for the guest\n");
 	default:
 		break;
 	}
@@ -1106,6 +1108,9 @@ static int pvinfo_mmio_write(struct intel_vgpu *vgpu, unsigned int offset,
 	case _vgtif_reg(execlist_context_descriptor_lo):
 	case _vgtif_reg(execlist_context_descriptor_hi):
 		break;
+	case _vgtif_reg(rsv5[0])..._vgtif_reg(rsv5[3]):
+		enter_failsafe_mode(vgpu, GVT_FAILSAFE_INSUFFICIENT_RESOURCE);
+		break;
 	default:
 		gvt_err("invalid pvinfo write offset %x bytes %x data %x\n",
 				offset, bytes, data);