Re: [PATCH v2] drm/xe/pf: Implement pci_driver.sriov_configure callback

["Nilawar, Badal" <badal.nilawar@intel.com>]

On 26-04-2024 20:37, Piotr Piórkowski wrote:
> Michal Wajdeczko <michal.wajdeczko@intel.com> wrote on pią [2024-kwi-26 15:22:17 +0200]:
>> The PCI subsystem already exposes the "sriov_numvfs" attribute
>> that users can use to enable or disable SR-IOV VFs. Add custom
>> implementation of the .sriov_configure callback defined by the
>> pci_driver to perform additional steps, including fair VFs
>> provisioning with the resources, as required by our platforms.
>>
>> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
>> Cc: Piotr Piórkowski <piotr.piorkowski@intel.com>
>> ---
>> v2: check result of VFs provisioning (Piotr)
>>      use xe_sriov_pf_get_totalvfs consistently (Piotr)
>>      prefer VFID instead of plain a VF number (Piotr)
>> ---
>>   drivers/gpu/drm/xe/Makefile       |   1 +
>>   drivers/gpu/drm/xe/xe_pci.c       |   4 +
>>   drivers/gpu/drm/xe/xe_pci_sriov.c | 138 ++++++++++++++++++++++++++++++
>>   drivers/gpu/drm/xe/xe_pci_sriov.h |  13 +++
>>   4 files changed, 156 insertions(+)
>>   create mode 100644 drivers/gpu/drm/xe/xe_pci_sriov.c
>>   create mode 100644 drivers/gpu/drm/xe/xe_pci_sriov.h
>>
>> diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
>> index a67977edff5b..6acde66f0827 100644
>> --- a/drivers/gpu/drm/xe/Makefile
>> +++ b/drivers/gpu/drm/xe/Makefile
>> @@ -169,6 +169,7 @@ xe-$(CONFIG_PCI_IOV) += \
>>   	xe_lmtt.o \
>>   	xe_lmtt_2l.o \
>>   	xe_lmtt_ml.o \
>> +	xe_pci_sriov.o \
>>   	xe_sriov_pf.o
>>   
>>   # include helpers for tests even when XE is built-in
>> diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
>> index a0cf5dd803c2..f3efde939df4 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_sriov.h"
>>   #include "xe_pci_types.h"
>>   #include "xe_pm.h"
>>   #include "xe_sriov.h"
>> @@ -952,6 +953,9 @@ static struct pci_driver xe_pci_driver = {
>>   	.probe = xe_pci_probe,
>>   	.remove = xe_pci_remove,
>>   	.shutdown = xe_pci_shutdown,
>> +#ifdef CONFIG_PCI_IOV
>> +	.sriov_configure = xe_pci_sriov_configure,
>> +#endif
>>   #ifdef CONFIG_PM_SLEEP
>>   	.driver.pm = &xe_pm_ops,
>>   #endif
>> diff --git a/drivers/gpu/drm/xe/xe_pci_sriov.c b/drivers/gpu/drm/xe/xe_pci_sriov.c
>> new file mode 100644
>> index 000000000000..75248fdd6cee
>> --- /dev/null
>> +++ b/drivers/gpu/drm/xe/xe_pci_sriov.c
>> @@ -0,0 +1,138 @@
>> +// SPDX-License-Identifier: MIT
>> +/*
>> + * Copyright © 2023-2024 Intel Corporation
>> + */
>> +
>> +#include "xe_assert.h"
>> +#include "xe_device.h"
>> +#include "xe_gt_sriov_pf_config.h"
>> +#include "xe_pci_sriov.h"
>> +#include "xe_pm.h"
>> +#include "xe_sriov.h"
>> +#include "xe_sriov_pf_helpers.h"
>> +#include "xe_sriov_printk.h"
>> +
>> +static int pf_provision_vfs(struct xe_device *xe, unsigned int num_vfs)
>> +{
>> +	struct xe_gt *gt;
>> +	unsigned int id;
>> +	int result = 0, err;
>> +
>> +	for_each_gt(gt, xe, id) {
>> +		err = xe_gt_sriov_pf_config_set_fair(gt, VFID(1), num_vfs);
>> +		result = result ?: err;
>> +	}
>> +
>> +	return result;
>> +}
>> +
>> +static void pf_unprovision_vfs(struct xe_device *xe, unsigned int num_vfs)
>> +{
>> +	struct xe_gt *gt;
>> +	unsigned int id;
>> +	unsigned int n;
>> +
>> +	for_each_gt(gt, xe, id)
>> +		for (n = 1; n <= num_vfs; n++)
>> +			xe_gt_sriov_pf_config_release(gt, n, true);
>> +}
>> +
>> +static int pf_enable_vfs(struct xe_device *xe, int num_vfs)
>> +{
>> +	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
>> +	int total_vfs = xe_sriov_pf_get_totalvfs(xe);
>> +	int err;
>> +
>> +	xe_assert(xe, IS_SRIOV_PF(xe));
>> +	xe_assert(xe, num_vfs > 0);
>> +	xe_assert(xe, num_vfs <= total_vfs);
>> +	xe_sriov_dbg(xe, "enabling %u VF%s\n", num_vfs, str_plural(num_vfs));
>> +
>> +	/*
>> +	 * hold additional reference to the runtime PM as long as VFs are
>> +	 * enabled to keep GuC alive - will be released in pf_disable_vfs()
>> +	 */
AFAIK PF shouldn't be placed in lower power state than VF. With that in 
above comment we should mention PF alive rather than GuC alive.
>> +	xe_pm_runtime_get(xe);
>> +
>> +	err = pf_provision_vfs(xe, num_vfs);
>> +	if (err < 0)
>> +		goto failed;
>> +
>> +	err = pci_enable_sriov(pdev, num_vfs);
>> +	if (err < 0)
>> +		goto failed;
>> +
>> +	xe_sriov_info(xe, "Enabled %u of %u VF%s\n",
>> +		      num_vfs, total_vfs, str_plural(total_vfs));
>> +	return num_vfs;
>> +
>> +failed:
>> +	pf_unprovision_vfs(xe, num_vfs);
>> +	xe_pm_runtime_put(xe);
>> +
>> +	xe_sriov_notice(xe, "Failed to enable %u VF%s (%pe)\n",
>> +			num_vfs, str_plural(num_vfs), ERR_PTR(err));
>> +	return err;
>> +}
>> +
>> +static int pf_disable_vfs(struct xe_device *xe)
>> +{
>> +	struct device *dev = xe->drm.dev;
>> +	struct pci_dev *pdev = to_pci_dev(dev);
>> +	u16 num_vfs = pci_num_vf(pdev);
>> +
>> +	xe_assert(xe, IS_SRIOV_PF(xe));
>> +	xe_sriov_dbg(xe, "disabling %u VF%s\n", num_vfs, str_plural(num_vfs));
>> +
>> +	if (!num_vfs)
>> +		return 0;
>> +
>> +	pci_disable_sriov(pdev);
>> +
>> +	pf_unprovision_vfs(xe, num_vfs);
>> +
>> +	/* not needed anymore - see pf_enable_vfs() */
>> +	xe_pm_runtime_put(xe);
>> +
>> +	xe_sriov_info(xe, "Disabled %u VF%s\n", num_vfs, str_plural(num_vfs));
>> +	return 0;
>> +}
>> +
>> +/**
>> + * xe_pci_sriov_configure - Configure SR-IOV (enable/disable VFs).
>> + * @pdev: the &pci_dev
>> + * @num_vfs: number of VFs to enable or zero to disable all VFs
>> + *
>> + * This is the Xe implementation of struct pci_driver.sriov_configure callback.
>> + *
>> + * This callback will be called by the PCI subsystem to enable or disable SR-IOV
>> + * Virtual Functions (VFs) as requested by the used via the PCI sysfs interface.
>> + *
>> + * Return: number of configured VFs or a negative error code on failure.
>> + */
>> +int xe_pci_sriov_configure(struct pci_dev *pdev, int num_vfs)
>> +{
>> +	struct xe_device *xe = pdev_to_xe_device(pdev);
>> +	int ret;
>> +
>> +	if (!IS_SRIOV_PF(xe))
>> +		return -ENODEV;
>> +
>> +	if (num_vfs < 0)
>> +		return -EINVAL;
>> +
>> +	if (num_vfs > xe_sriov_pf_get_totalvfs(xe))
>> +		return -ERANGE;
>> +
>> +	if (num_vfs && pci_num_vf(pdev))
>> +		return -EBUSY;
>> +
>> +	xe_pm_runtime_get(xe);
I think this is not needed as rpm ref is already being held and released 
in vfs enable and disble function.

Regards,
Badal
>> +	if (num_vfs > 0)
>> +		ret = pf_enable_vfs(xe, num_vfs);
>> +	else
>> +		ret = pf_disable_vfs(xe);
>> +	xe_pm_runtime_put(xe);
>> +
>> +	return ret;
>> +}
>> diff --git a/drivers/gpu/drm/xe/xe_pci_sriov.h b/drivers/gpu/drm/xe/xe_pci_sriov.h
>> new file mode 100644
>> index 000000000000..3b8bfbf7e1d9
>> --- /dev/null
>> +++ b/drivers/gpu/drm/xe/xe_pci_sriov.h
>> @@ -0,0 +1,13 @@
>> +/* SPDX-License-Identifier: MIT */
>> +/*
>> + * Copyright © 2023-2024 Intel Corporation
>> + */
>> +
>> +#ifndef _XE_PCI_SRIOV_H_
>> +#define _XE_PCI_SRIOV_H_
>> +
>> +struct pci_dev;
>> +
>> +int xe_pci_sriov_configure(struct pci_dev *pdev, int num_vfs);
>> +
>> +#endif
> 
> 
> LGTM:
> Reviewed-by: Piotr Piórkowski <piotr.piorkowski@intel.com>
> 
>> -- 
>> 2.43.0
>>
>