Re: [PATCH v3 4/4] drm/xe/FLR: Support PCIe FLR

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On 22-04-2024 12:27, Aravind Iddamsetty wrote:
PCI subsystem provides callbacks to inform the driver about a request to
do function level reset by user, initiated by writing to sysfs entry
/sys/bus/pci/devices/.../reset. This will allow the driver to handle FLR
without the need to do unbind and rebind as the driver needs to
reinitialize the device afresh post FLR.

v2:
1. separate out gt idle and pci save/restore to a separate patch (Lucas)
2. Fixed the warnings seen around xe_guc_submit_stop, xe_guc_puc_fini

v3: declare xe_pci_err_handlers as static(Michal)

Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Cc: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
Cc: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Signed-off-by: Aravind Iddamsetty <aravind.iddamsetty@xxxxxxxxxxxxxxx>
---
  drivers/gpu/drm/xe/Makefile          |  1 +
  drivers/gpu/drm/xe/xe_device_types.h |  3 +
  drivers/gpu/drm/xe/xe_guc_pc.c       |  4 ++
  drivers/gpu/drm/xe/xe_pci.c          |  9 ++-
  drivers/gpu/drm/xe/xe_pci.h          |  2 +
  drivers/gpu/drm/xe/xe_pci_err.c      | 88 ++++++++++++++++++++++++++++
  drivers/gpu/drm/xe/xe_pci_err.h      | 13 ++++
  7 files changed, 119 insertions(+), 1 deletion(-)
  create mode 100644 drivers/gpu/drm/xe/xe_pci_err.c
  create mode 100644 drivers/gpu/drm/xe/xe_pci_err.h

diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
index 8bc62bfbc679..693971a1fac0 100644
--- a/drivers/gpu/drm/xe/Makefile
+++ b/drivers/gpu/drm/xe/Makefile
@@ -117,6 +117,7 @@ xe-y += xe_bb.o \
  	xe_module.o \
  	xe_pat.o \
  	xe_pci.o \
+	xe_pci_err.o \
  	xe_pcode.o \
  	xe_pm.o \
  	xe_preempt_fence.o \
diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
index 0a66555229e9..8c749b378a92 100644
--- a/drivers/gpu/drm/xe/xe_device_types.h
+++ b/drivers/gpu/drm/xe/xe_device_types.h
@@ -465,6 +465,9 @@ struct xe_device {
  	/** @pci_state: PCI state of device */
  	struct pci_saved_state *pci_state;
+ /** @pci_device_is_reset: device went through PCIe FLR */
+	bool pci_device_is_reset;
+
  	/* private: */
#if IS_ENABLED(CONFIG_DRM_XE_DISPLAY)
diff --git a/drivers/gpu/drm/xe/xe_guc_pc.c b/drivers/gpu/drm/xe/xe_guc_pc.c
index 509649d0e65e..efba0fbe2f5c 100644
--- a/drivers/gpu/drm/xe/xe_guc_pc.c
+++ b/drivers/gpu/drm/xe/xe_guc_pc.c
@@ -902,6 +902,10 @@ static void xe_guc_pc_fini(struct drm_device *drm, void *arg)
  		return;
  	}
+ /* We already have done this before going through a reset, so skip here */
+	if (xe->pci_device_is_reset)
+		return;
+
  	XE_WARN_ON(xe_force_wake_get(gt_to_fw(pc_to_gt(pc)), XE_FORCEWAKE_ALL));
  	XE_WARN_ON(xe_guc_pc_gucrc_disable(pc));
  	XE_WARN_ON(xe_guc_pc_stop(pc));
diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
index a62300990e19..b5a582afc9e7 100644
--- a/drivers/gpu/drm/xe/xe_pci.c
+++ b/drivers/gpu/drm/xe/xe_pci.c
@@ -23,6 +23,7 @@
  #include "xe_macros.h"
  #include "xe_mmio.h"
  #include "xe_module.h"
+#include "xe_pci_err.h"
  #include "xe_pci_types.h"
  #include "xe_pm.h"
  #include "xe_sriov.h"
@@ -738,7 +739,7 @@ static void xe_pci_remove(struct pci_dev *pdev)
  	pci_set_drvdata(pdev, NULL);
  }
-static int xe_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
+int xe_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
  {
  	const struct xe_device_desc *desc = (const void *)ent->driver_data;
  	const struct xe_subplatform_desc *subplatform_desc;
@@ -986,6 +987,11 @@ static const struct dev_pm_ops xe_pm_ops = {
  };
  #endif
+static const struct pci_error_handlers xe_pci_err_handlers = {
+	.reset_prepare = xe_pci_reset_prepare,
+	.reset_done = xe_pci_reset_done,
+};
+
  static struct pci_driver xe_pci_driver = {
  	.name = DRIVER_NAME,
  	.id_table = pciidlist,
@@ -995,6 +1001,7 @@ static struct pci_driver xe_pci_driver = {
  #ifdef CONFIG_PM_SLEEP
  	.driver.pm = &xe_pm_ops,
  #endif
+	.err_handler = &xe_pci_err_handlers,
  };
int xe_register_pci_driver(void)
diff --git a/drivers/gpu/drm/xe/xe_pci.h b/drivers/gpu/drm/xe/xe_pci.h
index 73b90a430d1f..9faf5380a09e 100644
--- a/drivers/gpu/drm/xe/xe_pci.h
+++ b/drivers/gpu/drm/xe/xe_pci.h
@@ -7,8 +7,10 @@
  #define _XE_PCI_H_
struct pci_dev;
+struct pci_device_id;
int xe_register_pci_driver(void);
  void xe_unregister_pci_driver(void);
  void xe_load_pci_state(struct pci_dev *pdev);
+int xe_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent);
  #endif
diff --git a/drivers/gpu/drm/xe/xe_pci_err.c b/drivers/gpu/drm/xe/xe_pci_err.c
new file mode 100644
index 000000000000..5306925ea2fa
--- /dev/null
+++ b/drivers/gpu/drm/xe/xe_pci_err.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2024 Intel Corporation
+ */
+
+#include <linux/pci.h>
+#include <drm/drm_drv.h>
+
+#include "xe_device.h"
+#include "xe_gt.h"
+#include "xe_gt_printk.h"
+#include "xe_pci.h"
+#include "xe_pci_err.h"
+#include "xe_pm.h"
+#include "xe_uc.h"
+
+/**
+ * xe_pci_reset_prepare - Called when user issued a PCIe reset
+ * via /sys/bus/pci/devices/.../reset.
+ * @pdev: PCI device struct
+ */
+void xe_pci_reset_prepare(struct pci_dev *pdev)
+{
+	struct xe_device *xe = pci_get_drvdata(pdev);
+	struct xe_gt *gt;
+	int id, err;
+
+	pci_warn(pdev, "preparing for PCIe reset\n");
+
+	drm_warn(&xe->drm, "removing device access to userspace\n");
+	drm_dev_unplug(&xe->drm);
+
+	xe_pm_runtime_get(xe);
+	/* idle the GTs */
+	for_each_gt(gt, xe, id) {
+		err = xe_force_wake_get(gt_to_fw(gt), XE_FORCEWAKE_ALL);
+		if (err)
+			goto reset;
+		xe_uc_reset_prepare(&gt->uc);
+		xe_gt_idle(gt);
+		err = xe_force_wake_put(gt_to_fw(gt), XE_FORCEWAKE_ALL);
+		XE_WARN_ON(err);
+	}
+	xe_pm_runtime_put(xe);
Is xe_save_pci_state() needed here?

Regards,
Badal Nilawar> +
+reset:
+	pci_disable_device(pdev);
+}
+
+/**
+ * xe_pci_reset_done - Called when PCIe reset is done.
+ * @pdev: PCI device struct
+ */
+void xe_pci_reset_done(struct pci_dev *pdev)
+{
+	const struct pci_device_id *ent = pci_match_id(pdev->driver->id_table, pdev);
+	struct xe_device *xe = pci_get_drvdata(pdev);
+
+	dev_info(&pdev->dev,
+		 "device went through PCIe reset, reenabling the device\n");
+
+	if (pci_enable_device(pdev)) {
+		dev_err(&pdev->dev,
+			"Cannot re-enable PCI device after reset\n");
+		return;
+	}
+	pci_set_master(pdev);
+	xe_load_pci_state(pdev);
+
+	xe->pci_device_is_reset = true;
+	/*
+	 * We want to completely clean the driver and even destroy
+	 * the xe private data and reinitialize afresh similar to
+	 * probe
+	 */
+	pdev->driver->remove(pdev);
+	if (pci_dev_msi_enabled(pdev))
+		pci_free_irq_vectors(pdev);
+
+	devm_drm_dev_release_action(&xe->drm);
+	pci_disable_device(pdev);
+
+	/*
+	 * if this fails the driver might be in a stale state, only option is
+	 * to unbind and rebind
+	 */
+	xe_pci_probe(pdev, ent);
+}
diff --git a/drivers/gpu/drm/xe/xe_pci_err.h b/drivers/gpu/drm/xe/xe_pci_err.h
new file mode 100644
index 000000000000..95a4c8ce9cf1
--- /dev/null
+++ b/drivers/gpu/drm/xe/xe_pci_err.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2024 Intel Corporation
+ */
+
+#ifndef _XE_PCI_ERR_H_
+#define _XE_PCI_ERR_H_
+
+struct pci_dev;
+
+void xe_pci_reset_prepare(struct pci_dev *pdev);
+void xe_pci_reset_done(struct pci_dev *pdev);
+#endif



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