drm/i915/gvt: emulate vgpu engine reset control behavior

When SW wishes to reset the render engine, it will program
engine's reset control register and wait response from HW.
We need emulate the behavior of this register so guest i915
driver could walk through the engine reset flow. The registers
are not emulated in gvt yet, this patch add the emulation
logic.

v2: add more desc info in commit message.

Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
Signed-off-by: Du, Changbin <changbin.du@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

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

@@ -1398,6 +1398,23 @@ static int gvt_reg_tlb_control_handler(struct intel_vgpu *vgpu,
 	return rc;
 }
 
+static int ring_reset_ctl_write(struct intel_vgpu *vgpu,
+	unsigned int offset, void *p_data, unsigned int bytes)
+{
+	u32 data;
+
+	write_vreg(vgpu, offset, p_data, bytes);
+	data = vgpu_vreg(vgpu, offset);
+
+	if (data & _MASKED_BIT_ENABLE(RESET_CTL_REQUEST_RESET))
+		data |= RESET_CTL_READY_TO_RESET;
+	else if (data & _MASKED_BIT_DISABLE(RESET_CTL_REQUEST_RESET))
+		data &= ~RESET_CTL_READY_TO_RESET;
+
+	vgpu_vreg(vgpu, offset) = data;
+	return 0;
+}
+
 #define MMIO_F(reg, s, f, am, rm, d, r, w) do { \
 	ret = new_mmio_info(gvt, INTEL_GVT_MMIO_OFFSET(reg), \
 		f, s, am, rm, d, r, w); \
@@ -2304,6 +2321,15 @@ static int init_broadwell_mmio_info(struct intel_gvt *gvt)
 
 	MMIO_RING_D(RING_ACTHD_UDW, D_BDW_PLUS);
 
+#define RING_REG(base) (base + 0xd0)
+	MMIO_RING_F(RING_REG, 4, F_RO, 0,
+		~_MASKED_BIT_ENABLE(RESET_CTL_REQUEST_RESET), D_BDW_PLUS, NULL,
+		ring_reset_ctl_write);
+	MMIO_F(RING_REG(GEN8_BSD2_RING_BASE), 4, F_RO, 0,
+		~_MASKED_BIT_ENABLE(RESET_CTL_REQUEST_RESET), D_BDW_PLUS, NULL,
+		ring_reset_ctl_write);
+#undef RING_REG
+
 #define RING_REG(base) (base + 0x230)
 	MMIO_RING_DFH(RING_REG, D_BDW_PLUS, 0, NULL, elsp_mmio_write);
 	MMIO_DH(RING_REG(GEN8_BSD2_RING_BASE), D_BDW_PLUS, NULL, elsp_mmio_write);