linux-kernel - [PATCH] PCI: Reset IOV state on FLR to PF

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Date:   Wed, 22 Dec 2021 20:19:57 +0100
From:   Lukasz Maniak <lukasz.maniak@...ux.intel.com>
To:     Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Lukasz Maniak <lukasz.maniak@...ux.intel.com>,
        Łukasz Gieryk <lukasz.gieryk@...ux.intel.com>
Subject: [PATCH] PCI: Reset IOV state on FLR to PF

As per PCI Express specification, FLR to a PF resets the PF state as
well as the SR-IOV extended capability including VF Enable which means
that VFs no longer exist.

Currently, the IOV state is not updated during FLR, resulting in
non-compliant PCI driver behavior.

This patch introduces a simple function, called on the FLR path, that
removes the virtual function devices from the PCI bus and their
corresponding sysfs links with a final clear of the num_vfs value in IOV
state.

Signed-off-by: Lukasz Maniak <lukasz.maniak@...ux.intel.com>
---
 drivers/pci/iov.c | 21 +++++++++++++++++++++
 drivers/pci/pci.c |  2 ++
 drivers/pci/pci.h |  4 ++++
 3 files changed, 27 insertions(+)

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 0267977c9f17..69ee321027b4 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -1013,6 +1013,27 @@ int pci_iov_bus_range(struct pci_bus *bus)
 	return max ? max - bus->number : 0;
 }
 
+/**
+ * pci_reset_iov_state - reset the state of the IOV capability
+ * @dev: the PCI device
+ */
+void pci_reset_iov_state(struct pci_dev *dev)
+{
+	struct pci_sriov *iov = dev->sriov;
+
+	if (!dev->is_physfn)
+		return;
+	if (!iov->num_VFs)
+		return;
+
+	sriov_del_vfs(dev);
+
+	if (iov->link != dev->devfn)
+		sysfs_remove_link(&dev->dev.kobj, "dep_link");
+
+	iov->num_VFs = 0;
+}
+
 /**
  * pci_enable_sriov - enable the SR-IOV capability
  * @dev: the PCI device
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 3d2fb394986a..535f19d37e8d 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4694,6 +4694,8 @@ EXPORT_SYMBOL(pci_wait_for_pending_transaction);
  */
 int pcie_flr(struct pci_dev *dev)
 {
+	pci_reset_iov_state(dev);
+
 	if (!pci_wait_for_pending_transaction(dev))
 		pci_err(dev, "timed out waiting for pending transaction; performing function level reset anyway\n");
 
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 3d60cabde1a1..7bb144fbec76 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -480,6 +480,7 @@ void pci_iov_update_resource(struct pci_dev *dev, int resno);
 resource_size_t pci_sriov_resource_alignment(struct pci_dev *dev, int resno);
 void pci_restore_iov_state(struct pci_dev *dev);
 int pci_iov_bus_range(struct pci_bus *bus);
+void pci_reset_iov_state(struct pci_dev *dev);
 extern const struct attribute_group sriov_pf_dev_attr_group;
 extern const struct attribute_group sriov_vf_dev_attr_group;
 #else
@@ -501,6 +502,9 @@ static inline int pci_iov_bus_range(struct pci_bus *bus)
 {
 	return 0;
 }
+static inline void pci_reset_iov_state(struct pci_dev *dev)
+{
+}
 
 #endif /* CONFIG_PCI_IOV */
 

base-commit: fa55b7dcdc43c1aa1ba12bca9d2dd4318c2a0dbf
-- 
2.25.1