drm/xe/xe3p_lpg: flush shrinker bo cachelines manually

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)

V4: Add comments for L2 flush path
V3(Thomas/MattA/MattR): Restrict userptr with non-xa, then no need to
                        flush manually
V2(MattA): Expand commit description

Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patch.msgid.link/20260305121902.1892593-7-tejas.upadhyay@intel.com
Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>

drivers/gpu/drm/xe/xe_bo.c

@@ -689,7 +689,12 @@ 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;
+			/*
+			 * L2 cache may not be flushed, so ensure that is done in
+			 * xe_vm_invalidate_vma() below
+			 */
+			if (!xe_device_is_l2_flush_optimized(xe))
+				continue;
 		}
 
 		if (!idle) {

drivers/gpu/drm/xe/xe_device.c

@@ -1094,6 +1094,29 @@ 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;

drivers/gpu/drm/xe/xe_device.h

@@ -188,6 +188,7 @@ 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);