[PATCH V2 1/4] drm/xe/xe3p_lpg: flush shrinker bo cachelines manually

[Tejas Upadhyay <tejas.upadhyay@intel.com>]

XA, new pat_index introduced post xe3p_lpg, is memory shared between the
CPU and GPU is treated differently from other GPU memory when the Media
engine is power-gated.

XA is *always* flushed, like at the end-of-submssion (and maybe other
places), just that internally as an optimisation hw doesn't need to make
that a full flush (which will also include XA) when Media is
off/powergated, since it doesn't need to worry about GT caches vs Media
coherency, and only CPU vs GPU coherency, so can make that flush a
targeted XA flush, since stuff tagged with XA now means it's shared with
the CPU. The main implication is that we now need to somehow flush non-XA
before freeing system memory pages, otherwise dirty cachelines could be
flushed after the free (like if Media suddenly turns on and does a full flush)

V3(Thomas/MattA/MattR): Restrict userptr with non-xa, then no need to flush manually
V2(MattA): Expand commit description

Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
---
 drivers/gpu/drm/xe/xe_bo.c     |  3 ++-
 drivers/gpu/drm/xe/xe_device.c | 23 +++++++++++++++++++++++
 drivers/gpu/drm/xe/xe_device.h |  1 +
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
index d6c2cb959cdd..d2ee9701eae6 100644
--- a/drivers/gpu/drm/xe/xe_bo.c
+++ b/drivers/gpu/drm/xe/xe_bo.c
@@ -689,7 +689,8 @@ static int xe_bo_trigger_rebind(struct xe_device *xe, struct xe_bo *bo,
 
 		if (!xe_vm_in_fault_mode(vm)) {
 			drm_gpuvm_bo_evict(vm_bo, true);
-			continue;
+			if (!xe_device_is_l2_flush_optimized(xe))
+				continue;
 		}
 
 		if (!idle) {
diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
index 4b68a2d55651..94c9f17da4b4 100644
--- a/drivers/gpu/drm/xe/xe_device.c
+++ b/drivers/gpu/drm/xe/xe_device.c
@@ -1097,6 +1097,29 @@ static void tdf_request_sync(struct xe_device *xe)
 	}
 }
 
+/**
+ * xe_device_is_l2_flush_optimized - if L2 flush is optimized by HW
+ * @xe: The device to check.
+ *
+ * Return: true if the HW device optimizing L2 flush, false otherwise.
+ */
+bool xe_device_is_l2_flush_optimized(struct xe_device *xe)
+{
+	/* XA is *always* flushed, like at the end-of-submssion (and maybe other
+	 * places), just that internally as an optimisation hw doesn't need to make
+	 * that a full flush (which will also include XA) when Media is
+	 * off/powergated, since it doesn't need to worry about GT caches vs Media
+	 * coherency, and only CPU vs GPU coherency, so can make that flush a
+	 * targeted XA flush, since stuff tagged with XA now means it's shared with
+	 * the CPU. The main implication is that we now need to somehow flush non-XA before
+	 * freeing system memory pages, otherwise dirty cachelines could be flushed after the free
+	 * (like if Media suddenly turns on and does a full flush)
+	 */
+	if (GRAPHICS_VER(xe) >= 35 && !IS_DGFX(xe))
+		return true;
+	return false;
+}
+
 void xe_device_l2_flush(struct xe_device *xe)
 {
 	struct xe_gt *gt;
diff --git a/drivers/gpu/drm/xe/xe_device.h b/drivers/gpu/drm/xe/xe_device.h
index 39464650533b..dfbf96e12d2e 100644
--- a/drivers/gpu/drm/xe/xe_device.h
+++ b/drivers/gpu/drm/xe/xe_device.h
@@ -184,6 +184,7 @@ void xe_device_snapshot_print(struct xe_device *xe, struct drm_printer *p);
 u64 xe_device_canonicalize_addr(struct xe_device *xe, u64 address);
 u64 xe_device_uncanonicalize_addr(struct xe_device *xe, u64 address);
 
+bool xe_device_is_l2_flush_optimized(struct xe_device *xe);
 void xe_device_td_flush(struct xe_device *xe);
 void xe_device_l2_flush(struct xe_device *xe);
 
-- 
2.52.0