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

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Message-ID: <7i7dbkht3y2cqjtv6ojabph34c5o7s6qmddgax2wf2iv2hk4fl@35smvs5brdld>
Date: Wed, 26 Nov 2025 19:21:50 +0100
From: Michał Winiarski <michal.winiarski@...el.com>
To: Alex Williamson <alex@...zbot.org>
CC: 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>, Michal Wajdeczko <michal.wajdeczko@...el.com>,
	<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 Tue, Nov 25, 2025 at 11:34:03AM -0700, Alex Williamson wrote:
> On Tue, 25 Nov 2025 00:08:40 +0100
> Michał Winiarski <michal.winiarski@...el.com> wrote:
> > +/**
> > + * xe_sriov_vfio_wait_flr_done() - Wait for VF FLR completion.
> > + * @xe: the PF &xe_device obtained by calling xe_sriov_vfio_get_pf()
> > + * @vfid: the VF identifier (can't be 0)
> > + *
> > + * This function will wait until VF FLR is processed by PF on all tiles (or
> > + * until timeout occurs).
> > + *
> > + * Return: 0 on success or a negative error code on failure.
> > + */
> > +int xe_sriov_vfio_wait_flr_done(struct xe_device *xe, unsigned int vfid)
> > +{
> > +	if (!IS_SRIOV_PF(xe))
> > +		return -EPERM;
> > +	if (vfid == PFID || vfid > xe_sriov_pf_num_vfs(xe))
> > +		return -EINVAL;
> > +
> > +	guard(xe_pm_runtime_noresume)(xe);
> > +
> > +	return xe_sriov_pf_control_wait_flr(xe, vfid);
> > +}
> > +EXPORT_SYMBOL_FOR_MODULES(xe_sriov_vfio_wait_flr_done, "xe-vfio-pci");
> > +
> > +/**
> > + * xe_sriov_vfio_suspend_device() - Suspend VF.
> > + * @xe: the PF &xe_device obtained by calling xe_sriov_vfio_get_pf()
> > + * @vfid: the VF identifier (can't be 0)
> > + *
> > + * This function will pause VF on all tiles/GTs.
> > + *
> > + * Return: 0 on success or a negative error code on failure.
> > + */
> > +int xe_sriov_vfio_suspend_device(struct xe_device *xe, unsigned int vfid)
> > +{
> > +	if (!IS_SRIOV_PF(xe))
> > +		return -EPERM;
> > +	if (vfid == PFID || vfid > xe_sriov_pf_num_vfs(xe))
> > +		return -EINVAL;
> > +
> > +	guard(xe_pm_runtime_noresume)(xe);
> > +
> > +	return xe_sriov_pf_control_pause_vf(xe, vfid);
> > +}
> > +EXPORT_SYMBOL_FOR_MODULES(xe_sriov_vfio_suspend_device, "xe-vfio-pci");
> > +
> > +/**
> > + * xe_sriov_vfio_resume_device() - Resume VF.
> > + * @xe: the PF &xe_device obtained by calling xe_sriov_vfio_get_pf()
> > + * @vfid: the VF identifier (can't be 0)
> > + *
> > + * This function will resume VF on all tiles.
> > + *
> > + * Return: 0 on success or a negative error code on failure.
> > + */
> > +int xe_sriov_vfio_resume_device(struct xe_device *xe, unsigned int vfid)
> > +{
> > +	if (!IS_SRIOV_PF(xe))
> > +		return -EPERM;
> > +	if (vfid == PFID || vfid > xe_sriov_pf_num_vfs(xe))
> > +		return -EINVAL;
> > +
> > +	guard(xe_pm_runtime_noresume)(xe);
> > +
> > +	return xe_sriov_pf_control_resume_vf(xe, vfid);
> > +}
> > +EXPORT_SYMBOL_FOR_MODULES(xe_sriov_vfio_resume_device, "xe-vfio-pci");
> > +
> > +/**
> > + * xe_sriov_vfio_stop_copy_enter() - Initiate a VF device migration data save.
> > + * @xe: the PF &xe_device obtained by calling xe_sriov_vfio_get_pf()
> > + * @vfid: the VF identifier (can't be 0)
> > + *
> > + * Return: 0 on success or a negative error code on failure.
> > + */
> > +int xe_sriov_vfio_stop_copy_enter(struct xe_device *xe, unsigned int vfid)
> > +{
> > +	if (!IS_SRIOV_PF(xe))
> > +		return -EPERM;
> > +	if (vfid == PFID || vfid > xe_sriov_pf_num_vfs(xe))
> > +		return -EINVAL;
> > +
> > +	guard(xe_pm_runtime_noresume)(xe);
> > +
> > +	return xe_sriov_pf_control_trigger_save_vf(xe, vfid);
> > +}
> > +EXPORT_SYMBOL_FOR_MODULES(xe_sriov_vfio_stop_copy_enter, "xe-vfio-pci");
> > +
> > +/**
> > + * xe_sriov_vfio_stop_copy_exit() - Finish a VF device migration data save.
> > + * @xe: the PF &xe_device obtained by calling xe_sriov_vfio_get_pf()
> > + * @vfid: the VF identifier (can't be 0)
> > + *
> > + * Return: 0 on success or a negative error code on failure.
> > + */
> > +int xe_sriov_vfio_stop_copy_exit(struct xe_device *xe, unsigned int vfid)
> > +{
> > +	if (!IS_SRIOV_PF(xe))
> > +		return -EPERM;
> > +	if (vfid == PFID || vfid > xe_sriov_pf_num_vfs(xe))
> > +		return -EINVAL;
> > +
> > +	guard(xe_pm_runtime_noresume)(xe);
> > +
> > +	return xe_sriov_pf_control_finish_save_vf(xe, vfid);
> > +}
> > +EXPORT_SYMBOL_FOR_MODULES(xe_sriov_vfio_stop_copy_exit, "xe-vfio-pci");
> > +
> > +/**
> > + * xe_sriov_vfio_resume_data_enter() - Initiate a VF device migration data restore.
> > + * @xe: the PF &xe_device obtained by calling xe_sriov_vfio_get_pf()
> > + * @vfid: the VF identifier (can't be 0)
> > + *
> > + * Return: 0 on success or a negative error code on failure.
> > + */
> > +int xe_sriov_vfio_resume_data_enter(struct xe_device *xe, unsigned int vfid)
> > +{
> > +	if (!IS_SRIOV_PF(xe))
> > +		return -EPERM;
> > +	if (vfid == PFID || vfid > xe_sriov_pf_num_vfs(xe))
> > +		return -EINVAL;
> > +
> > +	guard(xe_pm_runtime_noresume)(xe);
> > +
> > +	return xe_sriov_pf_control_trigger_restore_vf(xe, vfid);
> > +}
> > +EXPORT_SYMBOL_FOR_MODULES(xe_sriov_vfio_resume_data_enter, "xe-vfio-pci");
> > +
> > +/**
> > + * xe_sriov_vfio_resume_data_exit() - Finish a VF device migration data restore.
> > + * @xe: the PF &xe_device obtained by calling xe_sriov_vfio_get_pf()
> > + * @vfid: the VF identifier (can't be 0)
> > + *
> > + * Return: 0 on success or a negative error code on failure.
> > + */
> > +int xe_sriov_vfio_resume_data_exit(struct xe_device *xe, unsigned int vfid)
> > +{
> > +	if (!IS_SRIOV_PF(xe))
> > +		return -EPERM;
> > +	if (vfid == PFID || vfid > xe_sriov_pf_num_vfs(xe))
> > +		return -EINVAL;
> > +
> > +	guard(xe_pm_runtime_noresume)(xe);
> > +
> > +	return xe_sriov_pf_control_finish_restore_vf(xe, vfid);
> > +}
> > +EXPORT_SYMBOL_FOR_MODULES(xe_sriov_vfio_resume_data_exit, "xe-vfio-pci");
> > +
> > +/**
> > + * xe_sriov_vfio_error() - Move VF device to error state.
> > + * @xe: the PF &xe_device obtained by calling xe_sriov_vfio_get_pf()
> > + * @vfid: the VF identifier (can't be 0)
> > + *
> > + * Reset is needed to move it out of error state.
> > + *
> > + * Return: 0 on success or a negative error code on failure.
> > + */
> > +int xe_sriov_vfio_error(struct xe_device *xe, unsigned int vfid)
> > +{
> > +	if (!IS_SRIOV_PF(xe))
> > +		return -EPERM;
> > +	if (vfid == PFID || vfid > xe_sriov_pf_num_vfs(xe))
> > +		return -EINVAL;
> > +
> > +	guard(xe_pm_runtime_noresume)(xe);
> > +
> > +	return xe_sriov_pf_control_stop_vf(xe, vfid);
> > +}
> > +EXPORT_SYMBOL_FOR_MODULES(xe_sriov_vfio_error, "xe-vfio-pci");
> > +
> > +/**
> > + * xe_sriov_vfio_data_read() - Read migration data from the VF device.
> > + * @xe: the PF &xe_device obtained by calling xe_sriov_vfio_get_pf()
> > + * @vfid: the VF identifier (can't be 0)
> > + * @buf: start address of userspace buffer
> > + * @len: requested read size from userspace
> > + *
> > + * Return: number of bytes that has been successfully read,
> > + *	   0 if no more migration data is available, -errno on failure.
> > + */
> > +ssize_t xe_sriov_vfio_data_read(struct xe_device *xe, unsigned int vfid,
> > +				char __user *buf, size_t len)
> > +{
> > +	if (!IS_SRIOV_PF(xe))
> > +		return -EPERM;
> > +	if (vfid == PFID || vfid > xe_sriov_pf_num_vfs(xe))
> > +		return -EINVAL;
> > +
> > +	guard(xe_pm_runtime_noresume)(xe);
> > +
> > +	return xe_sriov_pf_migration_read(xe, vfid, buf, len);
> > +}
> > +EXPORT_SYMBOL_FOR_MODULES(xe_sriov_vfio_data_read, "xe-vfio-pci");
> > +
> > +/**
> > + * xe_sriov_vfio_data_write() - Write migration data to the VF device.
> > + * @xe: the PF &xe_device obtained by calling xe_sriov_vfio_get_pf()
> > + * @vfid: the VF identifier (can't be 0)
> > + * @buf: start address of userspace buffer
> > + * @len: requested write size from userspace
> > + *
> > + * Return: number of bytes that has been successfully written, -errno on failure.
> > + */
> > +ssize_t xe_sriov_vfio_data_write(struct xe_device *xe, unsigned int vfid,
> > +				 const char __user *buf, size_t len)
> > +{
> > +	if (!IS_SRIOV_PF(xe))
> > +		return -EPERM;
> > +	if (vfid == PFID || vfid > xe_sriov_pf_num_vfs(xe))
> > +		return -EINVAL;
> > +
> > +	guard(xe_pm_runtime_noresume)(xe);
> > +
> > +	return xe_sriov_pf_migration_write(xe, vfid, buf, len);
> > +}
> > +EXPORT_SYMBOL_FOR_MODULES(xe_sriov_vfio_data_write, "xe-vfio-pci");
> > +
> > +/**
> > + * xe_sriov_vfio_stop_copy_size() - Get a size estimate of VF device migration data.
> > + * @xe: the PF &xe_device obtained by calling xe_sriov_vfio_get_pf()
> > + * @vfid: the VF identifier (can't be 0)
> > + *
> > + * Return: migration data size in bytes or a negative error code on failure.
> > + */
> > +ssize_t xe_sriov_vfio_stop_copy_size(struct xe_device *xe, unsigned int vfid)
> > +{
> > +	if (!IS_SRIOV_PF(xe))
> > +		return -EPERM;
> > +	if (vfid == PFID || vfid > xe_sriov_pf_num_vfs(xe))
> > +		return -EINVAL;
> > +
> > +	guard(xe_pm_runtime_noresume)(xe);
> > +
> > +	return xe_sriov_pf_migration_size(xe, vfid);
> > +}
> > +EXPORT_SYMBOL_FOR_MODULES(xe_sriov_vfio_stop_copy_size, "xe-vfio-pci");
> 
> The duplicated testing and identical structure of most of the above
> functions suggests a helper, if not full on definition by macro.
> Thanks,
> 
> Alex

I'll convert it to use macro definition for everything except
xe_sriov_vfio_data_write/xe_sriov_vfio_data_read.

Thanks,
-Michał