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

["Ghimiray, Himal Prasad" <himal.prasad.ghimiray@intel.com>]

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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@intel.com>
> Cc: Lucas De Marchi<lucas.demarchi@intel.com>
> Cc: Michal Wajdeczko<michal.wajdeczko@intel.com>
>
> Reviewed-by: Rodrigo Vivi<rodrigo.vivi@intel.com>
> Signed-off-by: Aravind Iddamsetty<aravind.iddamsetty@linux.intel.com>
> ---
>   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);
> +
> +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);
> +}


LGTM

Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>


> 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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