linux-kernel - Re: [PATCH v6 3/4] drm/xe/pf: Export helpers for VFIO

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Message-ID: <c4ff85ca-58fc-4f96-ad6a-808ba06c08fa@intel.com>
Date: Tue, 25 Nov 2025 15:38:17 +0100
From: Michal Wajdeczko <michal.wajdeczko@...el.com>
To: Michał Winiarski <michal.winiarski@...el.com>, "Alex
 Williamson" <alex@...zbot.org>, Lucas De Marchi <lucas.demarchi@...el.com>,
	Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
	"Rodrigo Vivi" <rodrigo.vivi@...el.com>, Jason Gunthorpe <jgg@...pe.ca>,
	Yishai Hadas <yishaih@...dia.com>, Kevin Tian <kevin.tian@...el.com>, Shameer
 Kolothum <skolothumtho@...dia.com>, <intel-xe@...ts.freedesktop.org>,
	<linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>, Matthew Brost
	<matthew.brost@...el.com>
CC: <dri-devel@...ts.freedesktop.org>, Jani Nikula
	<jani.nikula@...ux.intel.com>, Joonas Lahtinen
	<joonas.lahtinen@...ux.intel.com>, Tvrtko Ursulin <tursulin@...ulin.net>,
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, "Lukasz
 Laguna" <lukasz.laguna@...el.com>, Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH v6 3/4] drm/xe/pf: Export helpers for VFIO



On 11/25/2025 12:08 AM, Michał Winiarski wrote:
> Device specific VFIO driver variant for Xe will implement VF migration.
> Export everything that's needed for migration ops.
> 
> Signed-off-by: Michał Winiarski <michal.winiarski@...el.com>
> ---
>  drivers/gpu/drm/xe/Makefile        |   2 +
>  drivers/gpu/drm/xe/xe_sriov_vfio.c | 276 +++++++++++++++++++++++++++++
>  include/drm/intel/xe_sriov_vfio.h  |  30 ++++
>  3 files changed, 308 insertions(+)
>  create mode 100644 drivers/gpu/drm/xe/xe_sriov_vfio.c
>  create mode 100644 include/drm/intel/xe_sriov_vfio.h
> 
> diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
> index b848da79a4e18..0938b00a4c7fe 100644
> --- a/drivers/gpu/drm/xe/Makefile
> +++ b/drivers/gpu/drm/xe/Makefile
> @@ -184,6 +184,8 @@ xe-$(CONFIG_PCI_IOV) += \
>  	xe_sriov_pf_sysfs.o \
>  	xe_tile_sriov_pf_debugfs.o
>  
> +xe-$(CONFIG_XE_VFIO_PCI) += xe_sriov_vfio.o

hmm, shouldn't we also check for CONFIG_PCI_IOV ?
otherwise, some PF functions might not be available
or there some other implicit rule in Kconfig?

> +
>  # include helpers for tests even when XE is built-in
>  ifdef CONFIG_DRM_XE_KUNIT_TEST
>  xe-y += tests/xe_kunit_helpers.o
> diff --git a/drivers/gpu/drm/xe/xe_sriov_vfio.c b/drivers/gpu/drm/xe/xe_sriov_vfio.c
> new file mode 100644
> index 0000000000000..785f9a5027d10
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_sriov_vfio.c
> @@ -0,0 +1,276 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2025 Intel Corporation
> + */
> +
> +#include <drm/intel/xe_sriov_vfio.h>
> +#include <linux/cleanup.h>
> +
> +#include "xe_pci.h"
> +#include "xe_pm.h"
> +#include "xe_sriov_pf_control.h"
> +#include "xe_sriov_pf_helpers.h"
> +#include "xe_sriov_pf_migration.h"
> +
> +/**
> + * xe_sriov_vfio_get_pf() - Get PF &xe_device.
> + * @pdev: the VF &pci_dev device
> + *
> + * Return: pointer to PF &xe_device, NULL otherwise.
> + */
> +struct xe_device *xe_sriov_vfio_get_pf(struct pci_dev *pdev)
> +{
> +	return xe_pci_to_pf_device(pdev);
> +}
> +EXPORT_SYMBOL_FOR_MODULES(xe_sriov_vfio_get_pf, "xe-vfio-pci");
> +
> +/**
> + * xe_sriov_vfio_migration_supported() - Check if migration is supported.
> + * @xe: the PF &xe_device obtained by calling xe_sriov_vfio_get_pf()
> + *
> + * Return: true if migration is supported, false otherwise.
> + */
> +bool xe_sriov_vfio_migration_supported(struct xe_device *xe)
> +{

hmm, I'm wondering if maybe we should also check for NULL xe in all those
functions, as above helper function might return NULL in some unlikely case

but maybe this is too defensive

> +	if (!IS_SRIOV_PF(xe))
> +		return -EPERM;
> +
> +	return xe_sriov_pf_migration_supported(xe);
> +}
> +EXPORT_SYMBOL_FOR_MODULES(xe_sriov_vfio_migration_supported, "xe-vfio-pci");
> +

everything else lgtm, so:

Reviewed-by: Michal Wajdeczko <michal.wajdeczko@...el.com>