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    SubjectRe: [PATCH] PCI: Reset IOV state on FLR to PF
    On Wed, Dec 22, 2021 at 08:19:57PM +0100, Lukasz Maniak wrote:
    > 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.

    Can you add a specific reference to the spec, please?

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

    And include a little detail about what problem is observed? How would
    a user know this problem is occurring?

    > 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@linux.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
    >

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