drm/i915/gvt: vGPU interrupt virtualization.

This patch introduces vGPU interrupt emulation framework.

The vGPU intrerrupt emulation framework is an event-based interrupt
emulation framework. It's responsible for emulating GEN hardware interrupts
during emulating other HW behaviour.

It consists several components:

- Descriptions of interrupt register bit
- Upper level <-> lower level interrupt mapping
- GEN HW IER/IMR/IIR register emulation routines
- Event-based interrupt propagation interface

When a GVT-g component wants to inject an interrupt to a VM during a
emulation, first it should specify the event needs to be emulated and the
framework will deal with the rest of emulation:

- Generating related virtual IIR bit according to virtual IER and IMRs,
- Generate related virtual upper level virtual IIR bit accodring to the
per-platform interrupt mapping
- Injecting a MSI to VM

Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
diff --git a/drivers/gpu/drm/i915/gvt/hypercall.h b/drivers/gpu/drm/i915/gvt/hypercall.h
index eff8af5..f43614e 100644
--- a/drivers/gpu/drm/i915/gvt/hypercall.h
+++ b/drivers/gpu/drm/i915/gvt/hypercall.h
@@ -41,6 +41,7 @@
 	int (*detect_host)(void);
 	int (*attach_vgpu)(void *vgpu, unsigned long *handle);
 	void (*detach_vgpu)(unsigned long handle);
+	int (*inject_msi)(unsigned long handle, u32 addr, u16 data);
 };
 
 extern struct intel_gvt_mpt xengt_mpt;