drm/xe/pf: Implement pci_driver.sriov_configure callback

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>
Cc: Badal Nilawar <badal.nilawar@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Piotr Piórkowski <piotr.piorkowski@intel.com> #v2
Reviewed-by: Badal Nilawar <badal.nilawar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240506184121.2615-1-michal.wajdeczko@intel.com

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

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"
@@ -960,6 +961,9 @@ 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

drivers/gpu/drm/xe/xe_pci_sriov.c

@@ -0,0 +1,143 @@
+// 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));
+
+	/*
+	 * We must hold additional reference to the runtime PM to keep PF in D0
+	 * during VFs lifetime, as our VFs do not implement the PM capability.
+	 *
+	 * With PF being in D0 state, all VFs will also behave as in D0 state.
+	 * This will also keep GuC alive with all VFs' configurations.
+	 *
+	 * We will release this additional PM reference in pf_disable_vfs().
+	 */
+	xe_pm_runtime_get_noresume(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);
+	if (num_vfs > 0)
+		ret = pf_enable_vfs(xe, num_vfs);
+	else
+		ret = pf_disable_vfs(xe);
+	xe_pm_runtime_put(xe);
+
+	return ret;
+}

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