[PATCH 02/13] drm/xe: Separate AER reset state from device wedging

[Arvind Yadav <arvind.yadav@intel.com>]

PCI error recovery currently uses xe->wedged.flag to block driver
access. This mixes a temporary AER reset with a permanent device wedge.

If the device wedges during AER recovery, the wedge is not seen as the
first transition. The AER resume callback may then clear the flag and
make the permanently wedged device appear usable again.

Keep the old device blocked while slot reset removes it, and block the
new device until the AER resume callback.

The old AER path took a runtime PM reference to balance
xe_device_wedged_fini(), which drops one when wedged.flag is set. AER no
longer sets that flag, so keeping the Xe-owned reference would leak it.
pcie_do_recovery() holds a PCI-core runtime PM reference across the
error_detected, slot_reset and resume callbacks.

Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Arvind Yadav <arvind.yadav@intel.com>
---
 drivers/gpu/drm/xe/xe_bo.c            |  2 +-
 drivers/gpu/drm/xe/xe_device.c        |  4 ++--
 drivers/gpu/drm/xe/xe_device.h        | 12 ++++++++++++
 drivers/gpu/drm/xe/xe_guc_ct.c        |  4 ++--
 drivers/gpu/drm/xe/xe_guc_pc.c        | 10 +++++-----
 drivers/gpu/drm/xe/xe_guc_rc.c        |  4 ++--
 drivers/gpu/drm/xe/xe_guc_submit.c    |  8 ++++++--
 drivers/gpu/drm/xe/xe_guc_tlb_inval.c |  8 +++++++-
 drivers/gpu/drm/xe/xe_pci_error.c     | 22 +++++++++++-----------
 drivers/gpu/drm/xe/xe_sriov_pf.c      |  2 +-
 10 files changed, 49 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
index dde309821237..b86cd6030ed6 100644
--- a/drivers/gpu/drm/xe/xe_bo.c
+++ b/drivers/gpu/drm/xe/xe_bo.c
@@ -2094,7 +2094,7 @@ static vm_fault_t xe_bo_cpu_fault(struct vm_fault *vmf)
 	int err = 0;
 	int idx;
 
-	if (xe_device_wedged(xe) || !drm_dev_enter(&xe->drm, &idx))
+	if (xe_device_io_blocked(xe) || !drm_dev_enter(&xe->drm, &idx))
 		return ttm_bo_vm_dummy_page(vmf, vmf->vma->vm_page_prot);
 
 	ret = xe_bo_cpu_fault_fastpath(vmf, xe, bo, needs_rpm);
diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
index 74d566693dfd..a92e90acdf0d 100644
--- a/drivers/gpu/drm/xe/xe_device.c
+++ b/drivers/gpu/drm/xe/xe_device.c
@@ -225,7 +225,7 @@ static long xe_drm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	struct xe_device *xe = to_xe_device(file_priv->minor->dev);
 	long ret;
 
-	if (xe_device_wedged(xe))
+	if (xe_device_io_blocked(xe))
 		return -ECANCELED;
 
 	ACQUIRE(xe_pm_runtime_ioctl, pm)(xe);
@@ -243,7 +243,7 @@ static long xe_drm_compat_ioctl(struct file *file, unsigned int cmd, unsigned lo
 	struct xe_device *xe = to_xe_device(file_priv->minor->dev);
 	long ret;
 
-	if (xe_device_wedged(xe))
+	if (xe_device_io_blocked(xe))
 		return -ECANCELED;
 
 	ACQUIRE(xe_pm_runtime_ioctl, pm)(xe);
diff --git a/drivers/gpu/drm/xe/xe_device.h b/drivers/gpu/drm/xe/xe_device.h
index 6c4cfaebc44a..a3f876c60d76 100644
--- a/drivers/gpu/drm/xe/xe_device.h
+++ b/drivers/gpu/drm/xe/xe_device.h
@@ -212,6 +212,18 @@ static inline bool xe_device_wedged(struct xe_device *xe)
 	return atomic_read(&xe->wedged.flag);
 }
 
+/*
+ * Return true when device access must be blocked either permanently because
+ * the device is wedged or temporarily while PCI error recovery is running.
+ *
+ * Do not use this helper for one-way wedged-device decisions such as DMA
+ * isolation, IRQ resume suppression or recovery-method reporting.
+ */
+static inline bool xe_device_io_blocked(struct xe_device *xe)
+{
+	return xe_device_wedged(xe) || xe_device_is_in_reset(xe);
+}
+
 #ifdef CONFIG_DRM_XE_DEBUG_PAGE_SIZE
 static inline bool xe_debug_page_size_supported(struct xe_device *xe)
 {
diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
index 5c4733da385c..3c3fe4928fa2 100644
--- a/drivers/gpu/drm/xe/xe_guc_ct.c
+++ b/drivers/gpu/drm/xe/xe_guc_ct.c
@@ -1062,7 +1062,7 @@ static int __guc_ct_send_locked(struct xe_guc_ct *ct, const u32 *action,
 	xe_gt_assert(gt, g2h_len || !num_g2h);
 	lockdep_assert_held(&ct->lock);
 
-	if (xe_device_wedged(ct_to_xe(ct))) {
+	if (xe_device_io_blocked(ct_to_xe(ct))) {
 		ret = -ENOTRECOVERABLE;
 		goto out;
 	}
@@ -1813,7 +1813,7 @@ static int g2h_read(struct xe_guc_ct *ct, u32 *msg, bool fast_path)
 	xe_gt_assert(gt, xe_guc_ct_initialized(ct));
 	lockdep_assert_held(&ct->fast_lock);
 
-	if (xe_device_wedged(xe))
+	if (xe_device_io_blocked(xe))
 		return -ENOTRECOVERABLE;
 
 	if (ct->state == XE_GUC_CT_STATE_DISABLED)
diff --git a/drivers/gpu/drm/xe/xe_guc_pc.c b/drivers/gpu/drm/xe/xe_guc_pc.c
index 097b075bd89a..9fe397296dc4 100644
--- a/drivers/gpu/drm/xe/xe_guc_pc.c
+++ b/drivers/gpu/drm/xe/xe_guc_pc.c
@@ -188,7 +188,7 @@ static int pc_action_reset(struct xe_guc_pc *pc)
 	int ret;
 
 	ret = xe_guc_ct_send(ct, action, ARRAY_SIZE(action), 0, 0);
-	if (ret && !(xe_device_wedged(pc_to_xe(pc)) && ret == -ECANCELED))
+	if (ret && !(xe_device_io_blocked(pc_to_xe(pc)) && ret == -ECANCELED))
 		xe_gt_err(pc_to_gt(pc), "GuC PC reset failed: %pe\n",
 			  ERR_PTR(ret));
 
@@ -212,7 +212,7 @@ static int pc_action_query_task_state(struct xe_guc_pc *pc)
 
 	/* Blocking here to ensure the results are ready before reading them */
 	ret = xe_guc_ct_send_block(ct, action, ARRAY_SIZE(action));
-	if (ret && !(xe_device_wedged(pc_to_xe(pc)) && ret == -ECANCELED))
+	if (ret && !(xe_device_io_blocked(pc_to_xe(pc)) && ret == -ECANCELED))
 		xe_gt_err(pc_to_gt(pc), "GuC PC query task state failed: %pe\n",
 			  ERR_PTR(ret));
 
@@ -235,7 +235,7 @@ static int pc_action_set_param(struct xe_guc_pc *pc, u8 id, u32 value)
 		return -EAGAIN;
 
 	ret = xe_guc_ct_send(ct, action, ARRAY_SIZE(action), 0, 0);
-	if (ret && !(xe_device_wedged(pc_to_xe(pc)) && ret == -ECANCELED))
+	if (ret && !(xe_device_io_blocked(pc_to_xe(pc)) && ret == -ECANCELED))
 		xe_gt_err(pc_to_gt(pc), "GuC PC set param[%u]=%u failed: %pe\n",
 			  id, value, ERR_PTR(ret));
 
@@ -257,7 +257,7 @@ static int pc_action_unset_param(struct xe_guc_pc *pc, u8 id)
 		return -EAGAIN;
 
 	ret = xe_guc_ct_send(ct, action, ARRAY_SIZE(action), 0, 0);
-	if (ret && !(xe_device_wedged(pc_to_xe(pc)) && ret == -ECANCELED))
+	if (ret && !(xe_device_io_blocked(pc_to_xe(pc)) && ret == -ECANCELED))
 		xe_gt_err(pc_to_gt(pc), "GuC PC unset param failed: %pe",
 			  ERR_PTR(ret));
 
@@ -1357,7 +1357,7 @@ static void xe_guc_pc_fini_hw(void *arg)
 	struct xe_guc_pc *pc = arg;
 	struct xe_device *xe = pc_to_xe(pc);
 
-	if (xe_device_wedged(xe))
+	if (xe_device_io_blocked(xe))
 		return;
 
 	xe_guc_pc_stop(pc);
diff --git a/drivers/gpu/drm/xe/xe_guc_rc.c b/drivers/gpu/drm/xe/xe_guc_rc.c
index 99fa127b261f..eb5ec443f7ee 100644
--- a/drivers/gpu/drm/xe/xe_guc_rc.c
+++ b/drivers/gpu/drm/xe/xe_guc_rc.c
@@ -40,7 +40,7 @@ static int guc_action_setup_gucrc(struct xe_guc *guc, u32 control)
 	int ret;
 
 	ret = xe_guc_ct_send(&guc->ct, action, ARRAY_SIZE(action), 0, 0);
-	if (ret && !(xe_device_wedged(guc_to_xe(guc)) && ret == -ECANCELED))
+	if (ret && !(xe_device_io_blocked(guc_to_xe(guc)) && ret == -ECANCELED))
 		xe_gt_err(guc_to_gt(guc),
 			  "GuC RC setup %s(%u) failed (%pe)\n",
 			   control == GUCRC_HOST_CONTROL ? "HOST_CONTROL" :
@@ -73,7 +73,7 @@ static void xe_guc_rc_fini_hw(void *arg)
 	struct xe_device *xe = guc_to_xe(guc);
 	struct xe_gt *gt = guc_to_gt(guc);
 
-	if (xe_device_wedged(xe))
+	if (xe_device_io_blocked(xe))
 		return;
 
 	CLASS(xe_force_wake, fw_ref)(gt_to_fw(gt), XE_FW_GT);
diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
index 99d8c807ff05..a307af458cf8 100644
--- a/drivers/gpu/drm/xe/xe_guc_submit.c
+++ b/drivers/gpu/drm/xe/xe_guc_submit.c
@@ -2452,7 +2452,7 @@ static int guc_exec_queue_wait_suspend_done(struct xe_exec_queue *q, bool blocki
 						       WAIT_COND, HZ * 5);
 	}
 
-	if (!blocking && vf_recovery(guc) && !xe_device_wedged(xe))
+	if (!blocking && vf_recovery(guc) && !xe_device_io_blocked(xe))
 		return -EAGAIN;
 
 	if (!ret)
@@ -2694,7 +2694,11 @@ int xe_guc_submit_reset_prepare(struct xe_guc *guc)
 
 void xe_guc_submit_reset_wait(struct xe_guc *guc)
 {
-	wait_event(guc->ct.wq, xe_device_wedged(guc_to_xe(guc)) ||
+	/*
+	 * AER sets in_reset before declaring the GT wedged, which wakes this
+	 * waitqueue.
+	 */
+	wait_event(guc->ct.wq, xe_device_io_blocked(guc_to_xe(guc)) ||
 		   !xe_guc_read_stopped(guc));
 }
 
diff --git a/drivers/gpu/drm/xe/xe_guc_tlb_inval.c b/drivers/gpu/drm/xe/xe_guc_tlb_inval.c
index 046d0655122f..646e13671cd9 100644
--- a/drivers/gpu/drm/xe/xe_guc_tlb_inval.c
+++ b/drivers/gpu/drm/xe/xe_guc_tlb_inval.c
@@ -34,6 +34,9 @@ static int send_tlb_inval(struct xe_guc *guc, const u32 *action, int len)
 
 	xe_gt_assert(gt, action[1]);	/* Seqno */
 
+	if (xe_device_io_blocked(guc_to_xe(guc)))
+		return -ECANCELED;
+
 	xe_gt_stats_incr(gt, XE_GT_STATS_ID_TLB_INVAL, 1);
 	return xe_guc_ct_send(&guc->ct, action, len,
 			      G2H_LEN_DW_TLB_INVALIDATE, 1);
@@ -69,6 +72,9 @@ static int send_tlb_inval_ggtt(struct xe_tlb_inval *tlb_inval, u32 seqno)
 	 * signals waiters.
 	 */
 
+	if (xe_device_io_blocked(xe))
+		return -ECANCELED;
+
 	if (xe_guc_ct_enabled(&guc->ct) && guc->submission_state.enabled) {
 		u32 action[] = {
 			XE_GUC_ACTION_TLB_INVALIDATION,
@@ -77,7 +83,7 @@ static int send_tlb_inval_ggtt(struct xe_tlb_inval *tlb_inval, u32 seqno)
 		};
 
 		return send_tlb_inval(guc, action, ARRAY_SIZE(action));
-	} else if (xe_device_uc_enabled(xe) && !xe_device_wedged(xe)) {
+	} else if (xe_device_uc_enabled(xe)) {
 		struct xe_mmio *mmio = &gt->mmio;
 
 		if (IS_SRIOV_VF(xe))
diff --git a/drivers/gpu/drm/xe/xe_pci_error.c b/drivers/gpu/drm/xe/xe_pci_error.c
index 79ce0c671549..d82256d8721f 100644
--- a/drivers/gpu/drm/xe/xe_pci_error.c
+++ b/drivers/gpu/drm/xe/xe_pci_error.c
@@ -9,7 +9,6 @@
 #include "xe_gt.h"
 #include "xe_log.h"
 #include "xe_pci.h"
-#include "xe_pm.h"
 #include "xe_printk.h"
 #include "xe_ras.h"
 #include "xe_survivability_mode.h"
@@ -20,14 +19,15 @@ static void prepare_device_for_reset(struct pci_dev *pdev)
 	struct xe_gt *gt;
 	u8 id;
 
+
 	/*
-	 * Wedge the device to prevent userspace access but do not send the uevent.
-	 * xe_device_wedged_fini() releases runtime pm if wedged flag is set, so acquire a runtime
-	 * pm reference to avoid underflow.
+	 * Block device access while PCI error recovery is in progress.
+	 *
+	 * The old runtime PM reference balanced xe_device_wedged_fini() while
+	 * AER set wedged.flag. AER no longer sets that flag, and
+	 * pcie_do_recovery() holds its own runtime PM reference across the
+	 * recovery callbacks.
 	 */
-	if (!atomic_xchg(&xe->wedged.flag, 1))
-		xe_pm_runtime_get_noresume(xe);
-
 	xe_device_set_in_reset(xe);
 
 	for_each_gt(gt, xe, id)
@@ -116,7 +116,6 @@ static pci_ers_result_t xe_pci_error_slot_reset(struct pci_dev *pdev)
 	 * TODO: optimize by re-initializing only the hardware state and re-creating
 	 * kernel BOs.
 	 */
-	xe_device_clear_in_reset(xe);
 	pdev->driver->remove(pdev);
 	devres_release_group(&pdev->dev, xe->devres_group);
 
@@ -125,8 +124,8 @@ static pci_ers_result_t xe_pci_error_slot_reset(struct pci_dev *pdev)
 
 	xe = pdev_to_xe_device(pdev);
 
-	/* Wedge the device to prevent I/O operations till the resume callback */
-	atomic_set(&xe->wedged.flag, 1);
+	/* Block the new instance until the resume callback. */
+	xe_device_set_in_reset(xe);
 
 	return PCI_ERS_RESULT_RECOVERED;
 }
@@ -137,7 +136,8 @@ static void xe_pci_error_resume(struct pci_dev *pdev)
 
 	xe_info(xe, "PCI error: resume\n");
 
-	atomic_set(&xe->wedged.flag, 0);
+	/* Resume I/O operations. */
+	xe_device_clear_in_reset(xe);
 }
 
 const struct pci_error_handlers xe_pci_error_handlers = {
diff --git a/drivers/gpu/drm/xe/xe_sriov_pf.c b/drivers/gpu/drm/xe/xe_sriov_pf.c
index 33bd754d138f..568b7ed7c380 100644
--- a/drivers/gpu/drm/xe/xe_sriov_pf.c
+++ b/drivers/gpu/drm/xe/xe_sriov_pf.c
@@ -157,7 +157,7 @@ int xe_sriov_pf_wait_ready(struct xe_device *xe)
 	unsigned int id;
 	int err;
 
-	if (xe_device_wedged(xe))
+	if (xe_device_io_blocked(xe))
 		return -ECANCELED;
 
 	for_each_gt(gt, xe, id) {
-- 
2.43.0