Re: [PATCH v2 9/9] drm/xe/pci: Introduce PCIe FLR

["Laguna, Lukasz" <lukasz.laguna@intel.com>]

On 2/27/2026 18:49, Vivi, Rodrigo wrote:
> On Fri, 2026-02-27 at 22:30 +0530, Raag Jadav wrote:
>> With all the pieces in place, we can finally introduce PCIe Function
>> Level
>> Reset (FLR) handling which re-initializes hardware state without the
>> need
>> for reloading the driver from userspace. All VRAM contents are lost
>> along
>> with hardware state, so the driver takes care of recreating the
>> required
>> kernel bos as part of re-initialization, but user still needs to
>> recreate
>> user bos and reload context after PCIe FLR.
>>
>> Signed-off-by: Raag Jadav <raag.jadav@intel.com>
> Cc: Michał Winiarski <michal.winiarski@intel.com>
> Cc: Aravind Iddamsetty <aravind.iddamsetty@linux.intel.com>
>
> Do we really have everything in place? I'm missing the handling of VF
> here. Hence we would have the same deadlock pointed out by Michal when
> Aravind attempted it last time, no?!

This seems to be different from Aravind's previous attempt. Here we 
don't remove the driver and as a result we won't attempt to disable VFs, 
so the deadlock scenario shouldn't apply.

Lukasz

> We probably need to use the guc relay communication here so PF can
> inform VF of the FLR, then stop all the workload and wedge the device,
> before the AER triggers a kill of the VM, no?!
>
>> ---
>> v2: Spell out Function Level Reset (Jani)
>> ---
>>   drivers/gpu/drm/xe/Makefile     |   1 +
>>   drivers/gpu/drm/xe/xe_pci.c     |   1 +
>>   drivers/gpu/drm/xe/xe_pci.h     |   2 +
>>   drivers/gpu/drm/xe/xe_pci_err.c | 150
>> ++++++++++++++++++++++++++++++++
>>   4 files changed, 154 insertions(+)
>>   create mode 100644 drivers/gpu/drm/xe/xe_pci_err.c
>>
>> diff --git a/drivers/gpu/drm/xe/Makefile
>> b/drivers/gpu/drm/xe/Makefile
>> index 7fc67c320086..bc468a9afc48 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_err.o \
>>   	xe_pci_rebar.o \
>>   	xe_pcode.o \
>>   	xe_pm.o \
>> diff --git a/drivers/gpu/drm/xe/xe_pci.c
>> b/drivers/gpu/drm/xe/xe_pci.c
>> index 0a3bc5067a76..47a2f9de9d61 100644
>> --- a/drivers/gpu/drm/xe/xe_pci.c
>> +++ b/drivers/gpu/drm/xe/xe_pci.c
>> @@ -1301,6 +1301,7 @@ static struct pci_driver xe_pci_driver = {
>>   #ifdef CONFIG_PM_SLEEP
>>   	.driver.pm = &xe_pm_ops,
>>   #endif
>> +	.err_handler = &xe_pci_err_handlers,
>>   };
>>   
>>   /**
>> diff --git a/drivers/gpu/drm/xe/xe_pci.h
>> b/drivers/gpu/drm/xe/xe_pci.h
>> index 11bcc5fe2c5b..85e85e8508c3 100644
>> --- a/drivers/gpu/drm/xe/xe_pci.h
>> +++ b/drivers/gpu/drm/xe/xe_pci.h
>> @@ -8,6 +8,8 @@
>>   
>>   struct pci_dev;
>>   
>> +extern const struct pci_error_handlers xe_pci_err_handlers;
>> +
>>   int xe_register_pci_driver(void);
>>   void xe_unregister_pci_driver(void);
>>   struct xe_device *xe_pci_to_pf_device(struct pci_dev *pdev);
>> 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..16fc6a9f8289
>> --- /dev/null
>> +++ b/drivers/gpu/drm/xe/xe_pci_err.c
>> @@ -0,0 +1,150 @@
>> +// SPDX-License-Identifier: MIT
>> +/*
>> + * Copyright © 2026 Intel Corporation
>> + */
>> +
>> +#include "xe_bo_evict.h"
>> +#include "xe_device.h"
>> +#include "xe_gt.h"
>> +#include "xe_gt_idle.h"
>> +#include "xe_i2c.h"
>> +#include "xe_irq.h"
>> +#include "xe_late_bind_fw.h"
>> +#include "xe_pci.h"
>> +#include "xe_pcode.h"
>> +#include "xe_printk.h"
>> +#include "xe_pxp.h"
>> +#include "xe_wa.h"
>> +
>> +static int xe_flr_prepare(struct xe_device *xe)
>> +{
>> +	struct xe_gt *gt;
>> +	int err;
>> +	u8 id;
>> +
>> +	err = xe_pxp_pm_suspend(xe->pxp);
>> +	if (err)
>> +		return err;
>> +
>> +	xe_late_bind_wait_for_worker_completion(&xe->late_bind);
>> +
>> +	for_each_gt(gt, xe, id)
>> +		xe_gt_flr_prepare(gt);
>> +
>> +	xe_irq_disable(xe);
>> +
>> +	// TODO: Drop all user bos
>> +	xe_bo_pci_dev_remove_pinned(xe);
>> +
>> +	return 0;
>> +}
>> +
>> +static int xe_flr_done(struct xe_device *xe)
>> +{
>> +	struct xe_tile *tile;
>> +	struct xe_gt *gt;
>> +	int err;
>> +	u8 id;
>> +
>> +	for_each_gt(gt, xe, id)
>> +		xe_gt_idle_disable_c6(gt);
>> +
>> +	for_each_tile(tile, xe, id)
>> +		xe_wa_apply_tile_workarounds(tile);
>> +
>> +	err = xe_pcode_ready(xe, true);
>> +	if (err)
>> +		return err;
>> +
>> +	xe_device_assert_lmem_ready(xe);
>> +
>> +	err = xe_bo_restore_map(xe);
>> +	if (err)
>> +		return err;
>> +
>> +	for_each_gt(gt, xe, id) {
>> +		err = xe_gt_flr_done(gt);
>> +		if (err)
>> +			return err;
>> +	}
>> +
>> +	xe_i2c_pm_resume(xe, true);
>> +
>> +	xe_irq_resume(xe);
>> +
>> +	for_each_gt(gt, xe, id) {
>> +		err = xe_gt_resume(gt);
>> +		if (err)
>> +			return err;
>> +	}
>> +
>> +	xe_pxp_pm_resume(xe->pxp);
>> +
>> +	xe_late_bind_fw_load(&xe->late_bind);
>> +
>> +	return 0;
>> +}
>> +
>> +static void xe_pci_reset_prepare(struct pci_dev *pdev)
>> +{
>> +	struct xe_device *xe = pdev_to_xe_device(pdev);
>> +
>> +	/* TODO: Extend support as a follow-up */
>> +	if (!IS_DGFX(xe) || IS_SRIOV_VF(xe) || pci_num_vf(pdev) ||
>> xe->info.probe_display) {
>> +		xe_err(xe, "PCIe FLR not supported\n");
>> +		return;
>> +	}
>> +
>> +	/* Wedge the device to prevent userspace access but don't
>> send the event yet */
>> +	atomic_set(&xe->wedged.flag, 1);
>> +
>> +	/*
>> +	 * The hardware could be in corrupted state and access
>> unreliable, but we try to
>> +	 * update data structures and cleanup any pending work to
>> avoid side effects during
>> +	 * PCIe FLR. This will be similar to xe_pm_suspend() flow
>> but without migration.
>> +	 */
>> +	if (xe_flr_prepare(xe)) {
>> +		xe_err(xe, "Failed to prepare for PCIe FLR\n");
>> +		return;
>> +	}
>> +
>> +	xe_info(xe, "Prepared for PCIe FLR\n");
>> +}
>> +
>> +static void xe_pci_reset_done(struct pci_dev *pdev)
>> +{
>> +	struct xe_device *xe = pdev_to_xe_device(pdev);
>> +
>> +	/* TODO: Extend support as a follow-up */
>> +	if (!IS_DGFX(xe) || IS_SRIOV_VF(xe) || pci_num_vf(pdev) ||
>> xe->info.probe_display)
>> +		return;
>> +
>> +	if (!xe_device_wedged(xe)) {
>> +		xe_err(xe, "Device in unexpected state, re-
>> initialization aborted\n");
>> +		return;
>> +	}
>> +
>> +	/*
>> +	 * We already have the data structures intact, so try to re-
>> initialize the device.
>> +	 * This will be similar to xe_pm_resume() flow, except we'll
>> also need to recreate
>> +	 * all VRAM contents.
>> +	 */
>> +	if (xe_flr_done(xe)) {
>> +		xe_err(xe, "Re-initialization failed\n");
>> +		return;
>> +	}
>> +
>> +	/* Unwedge to allow userspace access */
>> +	atomic_set(&xe->wedged.flag, 0);
>> +
>> +	xe_info(xe, "Re-initialization success\n");
>> +}
>> +
>> +/*
>> + * PCIe Function Level Reset (FLR) support only.
>> + * TODO: Add PCIe error handlers using similar flow.
>> + */
>> +const struct pci_error_handlers xe_pci_err_handlers = {
>> +	.reset_prepare = xe_pci_reset_prepare,
>> +	.reset_done = xe_pci_reset_done,
>> +};