Re: [PATCH v2 03/11] drm/xe/xe_pci_error: Implement PCI error recovery callbacks

[Raag Jadav <raag.jadav@intel.com>]

On Mon, Mar 02, 2026 at 03:51:58PM +0530, Riana Tauro wrote:
> Add error_detected, mmio_enabled, slot_reset and resume
> recovery callbacks to handle PCIe Advanced Error Reporting
> (AER) errors.
> 
> For fatal errors, the device is wedged and becomes
> inaccessible. Return PCI_ERS_RESULT_SLOT_RESET from
> error_detected to request a Secondary Bus Reset (SBR).
> 
> For non-fatal errors, return PCI_ERS_RESULT_CAN_RECOVER from
> error_detected to trigger the mmio_enabled callback. In this callback,
> the device is queried to determine the error cause and attempt
> recovery based on the error type.
> 
> Once the secondary bus reset(SBR) is completed the slot_reset callback
> cleanly removes and reprobe the device to restore functionality.
> 
> Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>
> Cc: Matt Roper <matthew.d.roper@intel.com>
> Signed-off-by: Riana Tauro <riana.tauro@intel.com>
> ---
> v2: re-order linux headers
>     reword error messages
>     do not clear in_recovery after remove
>     return PCI_ERS_RESULT_DISCONNECT if probe fails (Michal)
>     only wedge device do not send uevent (Raag)
>     set recovery flag in error_detected and clear on resume
>     add default switch case (Mallesh)
> ---
>  drivers/gpu/drm/xe/Makefile          |  1 +
>  drivers/gpu/drm/xe/xe_device.h       | 15 +++++
>  drivers/gpu/drm/xe/xe_device_types.h |  3 +
>  drivers/gpu/drm/xe/xe_pci.c          |  3 +
>  drivers/gpu/drm/xe/xe_pci_error.c    | 99 ++++++++++++++++++++++++++++
>  5 files changed, 121 insertions(+)
>  create mode 100644 drivers/gpu/drm/xe/xe_pci_error.c
> 
> diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
> index 1890bbd1b28d..417b030e5ce7 100644
> --- a/drivers/gpu/drm/xe/Makefile
> +++ b/drivers/gpu/drm/xe/Makefile
> @@ -99,6 +99,7 @@ xe-y += xe_bb.o \
>  	xe_page_reclaim.o \
>  	xe_pat.o \
>  	xe_pci.o \
> +	xe_pci_error.o \
>  	xe_pci_rebar.o \
>  	xe_pcode.o \
>  	xe_pm.o \
> diff --git a/drivers/gpu/drm/xe/xe_device.h b/drivers/gpu/drm/xe/xe_device.h
> index 39464650533b..972f43d20f1a 100644
> --- a/drivers/gpu/drm/xe/xe_device.h
> +++ b/drivers/gpu/drm/xe/xe_device.h
> @@ -43,6 +43,21 @@ static inline struct xe_device *ttm_to_xe_device(struct ttm_device *ttm)
>  	return container_of(ttm, struct xe_device, ttm);
>  }
>  
> +static inline bool xe_device_is_in_recovery(struct xe_device *xe)
> +{
> +	return atomic_read(&xe->in_recovery);
> +}
> +
> +static inline void xe_device_set_in_recovery(struct xe_device *xe)
> +{
> +	atomic_set(&xe->in_recovery, 1);
> +}
> +
> +static inline void xe_device_clear_in_recovery(struct xe_device *xe)
> +{
> +	 atomic_set(&xe->in_recovery, 0);
> +}
> +
>  struct xe_device *xe_device_create(struct pci_dev *pdev,
>  				   const struct pci_device_id *ent);
>  int xe_device_probe_early(struct xe_device *xe);
> diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
> index 5599534384fa..616d74792902 100644
> --- a/drivers/gpu/drm/xe/xe_device_types.h
> +++ b/drivers/gpu/drm/xe/xe_device_types.h
> @@ -504,6 +504,9 @@ struct xe_device {
>  		bool inconsistent_reset;
>  	} wedged;
>  
> +	/** @in_recovery: Indicates if device is in recovery */
> +	atomic_t in_recovery;
> +
>  	/** @bo_device: Struct to control async free of BOs */
>  	struct xe_bo_dev {
>  		/** @bo_device.async_free: Free worker */
> diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
> index ad1e5ef2ee89..825489287f28 100644
> --- a/drivers/gpu/drm/xe/xe_pci.c
> +++ b/drivers/gpu/drm/xe/xe_pci.c
> @@ -1313,6 +1313,8 @@ static const struct dev_pm_ops xe_pm_ops = {
>  };
>  #endif
>  
> +extern const struct pci_error_handlers xe_pci_error_handlers;
> +
>  static struct pci_driver xe_pci_driver = {
>  	.name = DRIVER_NAME,
>  	.id_table = pciidlist,
> @@ -1320,6 +1322,7 @@ static struct pci_driver xe_pci_driver = {
>  	.remove = xe_pci_remove,
>  	.shutdown = xe_pci_shutdown,
>  	.sriov_configure = xe_pci_sriov_configure,
> +	.err_handler = &xe_pci_error_handlers,
>  #ifdef CONFIG_PM_SLEEP
>  	.driver.pm = &xe_pm_ops,
>  #endif
> diff --git a/drivers/gpu/drm/xe/xe_pci_error.c b/drivers/gpu/drm/xe/xe_pci_error.c
> new file mode 100644
> index 000000000000..d4896a4a5014
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_pci_error.c
> @@ -0,0 +1,99 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2026 Intel Corporation
> + */
> +#include <linux/pci.h>
> +
> +#include <drm/drm_drv.h>
> +
> +#include "xe_device.h"
> +#include "xe_gt.h"
> +#include "xe_pci.h"
> +#include "xe_uc.h"
> +
> +static void xe_pci_error_handling(struct pci_dev *pdev)
> +{
> +	struct xe_device *xe = pdev_to_xe_device(pdev);
> +	struct xe_gt *gt;
> +	u8 id;
> +
> +	/* Wedge the device to prevent userspace access but don't send the event yet */
> +	atomic_set(&xe->wedged.flag, 1);
> +
> +	for_each_gt(gt, xe, id)
> +		xe_gt_declare_wedged(gt);
> +
> +	pci_disable_device(pdev);
> +}
> +
> +static pci_ers_result_t xe_pci_error_detected(struct pci_dev *pdev, pci_channel_state_t state)
> +{
> +	struct xe_device *xe = pdev_to_xe_device(pdev);
> +
> +	dev_err(&pdev->dev, "Xe Pci error recovery: error detected state %d\n", state);
> +
> +	xe_device_set_in_recovery(xe);

This looks similar to wedged.flag. If we rather stop exec queues and
cancel/flush all pending work properly, perhaps we won't be needing
this. Let me explore what can be done here.

> +	switch (state) {
> +	case pci_channel_io_normal:
> +		return PCI_ERS_RESULT_CAN_RECOVER;
> +	case pci_channel_io_frozen:
> +		xe_pci_error_handling(pdev);
> +		return PCI_ERS_RESULT_NEED_RESET;
> +	case pci_channel_io_perm_failure:
> +		return PCI_ERS_RESULT_DISCONNECT;
> +	default:
> +		dev_err(&pdev->dev, "Unknown state %d\n", state);
> +		return PCI_ERS_RESULT_NEED_RESET;
> +	}
> +}
> +
> +static pci_ers_result_t xe_pci_error_mmio_enabled(struct pci_dev *pdev)
> +{
> +	dev_err(&pdev->dev, "Xe Pci error recovery: MMIO enabled\n");
> +
> +	return PCI_ERS_RESULT_NEED_RESET;
> +}
> +
> +static pci_ers_result_t xe_pci_error_slot_reset(struct pci_dev *pdev)
> +{
> +	const struct pci_device_id *ent = pci_match_id(pdev->driver->id_table, pdev);
> +	struct xe_device *xe = pdev_to_xe_device(pdev);
> +
> +	dev_err(&pdev->dev, "Xe Pci error recovery: Slot reset\n");
> +
> +	pci_restore_state(pdev);
> +
> +	if (pci_enable_device(pdev)) {
> +		dev_err(&pdev->dev,
> +			"Cannot re-enable PCI device after reset\n");
> +		return PCI_ERS_RESULT_DISCONNECT;
> +	}
> +
> +	/*
> +	 * Secondary Bus Reset wipes out all device memory
> +	 * requiring XE KMD to perform a device removal and reprobe.
> +	 */
> +	pdev->driver->remove(pdev);

A bit fishy, but does the job for now ;)

Raag

> +	if (!pdev->driver->probe(pdev, ent))
> +		return PCI_ERS_RESULT_RECOVERED;
> +
> +	return PCI_ERS_RESULT_DISCONNECT;
> +}
> +
> +static void xe_pci_error_resume(struct pci_dev *pdev)
> +{
> +	struct xe_device *xe = pdev_to_xe_device(pdev);
> +
> +	dev_info(&pdev->dev, "Xe Pci error recovery: Recovered\n");
> +
> +	xe_device_clear_in_recovery(xe);
> +}
> +
> +const struct pci_error_handlers xe_pci_error_handlers = {
> +	.error_detected	= xe_pci_error_detected,
> +	.mmio_enabled	= xe_pci_error_mmio_enabled,
> +	.slot_reset	= xe_pci_error_slot_reset,
> +	.resume		= xe_pci_error_resume,
> +};
> -- 
> 2.47.1
>