[PATCH 1/2] drm/xe: Fix tlb invalidation when wedging

[Lucas De Marchi]

If GuC fails to load, the driver wedges, but in the process it tries to
do stuff that may not be initialized yet. This moves the
xe_gt_tlb_invalidation_init() to be done earlier: as its own doc says,
it's a software-only initialization and should had been named with the
_early() suffix.

Move it to be called by xe_gt_init_early(), so the locks and seqno are
initialized, avoiding a NULL ptr deref when wedging:

	xe 0000:03:00.0: [drm] *ERROR* GT0: load failed: status: Reset = 0, BootROM = 0x50, UKernel = 0x00, MIA = 0x00, Auth = 0x01
	xe 0000:03:00.0: [drm] *ERROR* GT0: firmware signature verification failed
	xe 0000:03:00.0: [drm] *ERROR* CRITICAL: Xe has declared device 0000:03:00.0 as wedged.
	...
	BUG: kernel NULL pointer dereference, address: 0000000000000000
	#PF: supervisor read access in kernel mode
	#PF: error_code(0x0000) - not-present page
	PGD 0 P4D 0
	Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI
	CPU: 9 UID: 0 PID: 3908 Comm: modprobe Tainted: G     U  W          6.13.0-rc4-xe+ #3
	Tainted: [U]=USER, [W]=WARN
	Hardware name: Intel Corporation Alder Lake Client Platform/AlderLake-S ADP-S DDR5 UDIMM CRB, BIOS ADLSFWI1.R00.3275.A00.2207010640 07/01/2022
	RIP: 0010:xe_gt_tlb_invalidation_reset+0x75/0x110 [xe]

This can be easily triggered by poking the GuC binary to force a
signature failure. There will still be an extra message,

	xe 0000:03:00.0: [drm] *ERROR* GT0: GuC mmio request 0x4100: no reply 0x4100

but that's better than a NULL ptr deref.

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/3956
Fixes: 7dbe8af13c18 ("drm/xe: Wedge the entire device")
Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
---
 drivers/gpu/drm/xe/xe_gt.c                  | 8 ++++----
 drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c | 4 ++--
 drivers/gpu/drm/xe/xe_gt_tlb_invalidation.h | 3 ++-
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_gt.c b/drivers/gpu/drm/xe/xe_gt.c
index 41ab7fbebc193..26e64530ada27 100644
--- a/drivers/gpu/drm/xe/xe_gt.c
+++ b/drivers/gpu/drm/xe/xe_gt.c
@@ -387,6 +387,10 @@ int xe_gt_init_early(struct xe_gt *gt)
 	xe_force_wake_init_gt(gt, gt_to_fw(gt));
 	spin_lock_init(&gt->global_invl_lock);
 
+	err = xe_gt_tlb_invalidation_init_early(gt);
+	if (err)
+		return err;
+
 	return 0;
 }
 
@@ -588,10 +592,6 @@ int xe_gt_init(struct xe_gt *gt)
 		xe_hw_fence_irq_init(&gt->fence_irq[i]);
 	}
 
-	err = xe_gt_tlb_invalidation_init(gt);
-	if (err)
-		return err;
-
 	err = xe_gt_pagefault_init(gt);
 	if (err)
 		return err;
diff --git a/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c b/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
index 665927b80e9ea..257b500e17037 100644
--- a/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
+++ b/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
@@ -106,7 +106,7 @@ static void xe_gt_tlb_fence_timeout(struct work_struct *work)
 }
 
 /**
- * xe_gt_tlb_invalidation_init - Initialize GT TLB invalidation state
+ * xe_gt_tlb_invalidation_init_early - Initialize GT TLB invalidation state
  * @gt: graphics tile
  *
  * Initialize GT TLB invalidation state, purely software initialization, should
@@ -114,7 +114,7 @@ static void xe_gt_tlb_fence_timeout(struct work_struct *work)
  *
  * Return: 0 on success, negative error code on error.
  */
-int xe_gt_tlb_invalidation_init(struct xe_gt *gt)
+int xe_gt_tlb_invalidation_init_early(struct xe_gt *gt)
 {
 	gt->tlb_invalidation.seqno = 1;
 	INIT_LIST_HEAD(&gt->tlb_invalidation.pending_fences);
diff --git a/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.h b/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.h
index 00b1c6c01e8d9..672acfcdf0d70 100644
--- a/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.h
+++ b/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.h
@@ -14,7 +14,8 @@ struct xe_gt;
 struct xe_guc;
 struct xe_vma;
 
-int xe_gt_tlb_invalidation_init(struct xe_gt *gt);
+int xe_gt_tlb_invalidation_init_early(struct xe_gt *gt);
+
 void xe_gt_tlb_invalidation_reset(struct xe_gt *gt);
 int xe_gt_tlb_invalidation_ggtt(struct xe_gt *gt);
 int xe_gt_tlb_invalidation_vma(struct xe_gt *gt,
-- 
2.47.0