[Intel-gfx] [PATCH v2] drm/i915/gvt: Fix cached atomics setting for Windows VM

[Zhenyu Wang]

We've seen recent regression with host and windows VM running
simultaneously that cause gpu hang or even crash. Finally bisect to
commit 58586680ffad ("drm/i915: Disable atomics in L3 for gen9"),
which seems cached atomics behavior difference caused regression
issue.

This tries to add new scratch register handler and add those in mmio
save/restore list for context switch. No gpu hang produced with this one.

Cc: stable at vger.kernel.org # 5.12+
Cc: "Xu, Terrence" <terrence.xu at intel.com>
Cc: "Bloomfield, Jon" <jon.bloomfield at intel.com>
Cc: "Ekstrand, Jason" <jason.ekstrand at intel.com>
Fixes: 58586680ffad ("drm/i915: Disable atomics in L3 for gen9")
Signed-off-by: Zhenyu Wang <zhenyuw at linux.intel.com>
---
 drivers/gpu/drm/i915/gvt/handlers.c     | 1 +
 drivers/gpu/drm/i915/gvt/mmio_context.c | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/gvt/handlers.c b/drivers/gpu/drm/i915/gvt/handlers.c
index 06024d321a1a..cde0a477fb49 100644
--- a/drivers/gpu/drm/i915/gvt/handlers.c
+++ b/drivers/gpu/drm/i915/gvt/handlers.c
@@ -3149,6 +3149,7 @@ static int init_bdw_mmio_info(struct intel_gvt *gvt)
 	MMIO_DFH(_MMIO(0xb100), D_BDW, F_CMD_ACCESS, NULL, NULL);
 	MMIO_DFH(_MMIO(0xb10c), D_BDW, F_CMD_ACCESS, NULL, NULL);
 	MMIO_D(_MMIO(0xb110), D_BDW);
+	MMIO_D(GEN9_SCRATCH_LNCF1, D_BDW_PLUS);
 
 	MMIO_F(_MMIO(0x24d0), 48, F_CMD_ACCESS | F_CMD_WRITE_PATCH, 0, 0,
 		D_BDW_PLUS, NULL, force_nonpriv_write);
diff --git a/drivers/gpu/drm/i915/gvt/mmio_context.c b/drivers/gpu/drm/i915/gvt/mmio_context.c
index b8ac80765461..f776c470914d 100644
--- a/drivers/gpu/drm/i915/gvt/mmio_context.c
+++ b/drivers/gpu/drm/i915/gvt/mmio_context.c
@@ -105,6 +105,8 @@ static struct engine_mmio gen9_engine_mmio_list[] __cacheline_aligned = {
 	{RCS0, COMMON_SLICE_CHICKEN2, 0xffff, true}, /* 0x7014 */
 	{RCS0, GEN9_CS_DEBUG_MODE1, 0xffff, false}, /* 0x20ec */
 	{RCS0, GEN8_L3SQCREG4, 0, false}, /* 0xb118 */
+	{RCS0, GEN9_SCRATCH1, 0, false}, /* 0xb11c */
+	{RCS0, GEN9_SCRATCH_LNCF1, 0, false}, /* 0xb008 */
 	{RCS0, GEN7_HALF_SLICE_CHICKEN1, 0xffff, true}, /* 0xe100 */
 	{RCS0, HALF_SLICE_CHICKEN2, 0xffff, true}, /* 0xe180 */
 	{RCS0, HALF_SLICE_CHICKEN3, 0xffff, true}, /* 0xe184 */
-- 
2.32.0.rc2