PCI/IOV: Reset total_VFs limit after detaching PF driver

The TotalVFs register in the SR-IOV capability is the hardware limit on the
number of VFs.  A PF driver can limit the number of VFs further with
pci_sriov_set_totalvfs().  When the PF driver is removed, reset any VF
limit that was imposed by the driver because that limit may not apply to
other drivers.

Before 8d85a7a4f2c9 ("PCI/IOV: Allow PF drivers to limit total_VFs to 0"),
pci_sriov_set_totalvfs(pdev, 0) meant "we can enable TotalVFs virtual
functions", and the nfp driver used that to remove the VF limit when the
driver unloads.

8d85a7a4f2c9 broke that because instead of removing the VF limit,
pci_sriov_set_totalvfs(pdev, 0) actually sets the limit to zero, and that
limit persists even if another driver is loaded.

We could fix that by making the nfp driver reset the limit when it unloads,
but it seems more robust to do it in the PCI core instead of relying on the
driver.

The regression scenario is:

  nfp_pci_probe (driver 1)
  ...
  nfp_pci_remove
    pci_sriov_set_totalvfs(pf->pdev, 0)   # limits VFs to 0

  ...
  nfp_pci_probe (driver 2)
    nfp_rtsym_read_le("nfd_vf_cfg_max_vfs")
    # no VF limit from firmware

Now driver 2 is broken because the VF limit is still 0 from driver 1.

Fixes: 8d85a7a4f2c9 ("PCI/IOV: Allow PF drivers to limit total_VFs to 0")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
[bhelgaas: changelog, rename functions]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index d0d73dbbd5ca4123fce20254a0bf6495dcbe1d9e..0f04ae648cf14bcc590ce55b5b91a5635b02c500 100644 (file)
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -574,6 +574,22 @@ void pci_iov_release(struct pci_dev *dev)
                sriov_release(dev);
 }
 
+/**
+ * pci_iov_remove - clean up SR-IOV state after PF driver is detached
+ * @dev: the PCI device
+ */
+void pci_iov_remove(struct pci_dev *dev)
+{
+       struct pci_sriov *iov = dev->sriov;
+
+       if (!dev->is_physfn)
+               return;
+
+       iov->driver_max_VFs = iov->total_VFs;
+       if (iov->num_VFs)
+               pci_warn(dev, "driver left SR-IOV enabled after remove\n");
+}
+
 /**
  * pci_iov_update_resource - update a VF BAR
  * @dev: the PCI device

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index c125d53033c69cafe42734c32935561547abbdba..6792292b5fc7055ab145703a3e718e50d0d4751c 100644 (file)
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -445,6 +445,7 @@ static int pci_device_remove(struct device *dev)
                }
                pcibios_free_irq(pci_dev);
                pci_dev->driver = NULL;
+               pci_iov_remove(pci_dev);
        }
 
        /* Undo the runtime PM settings in local_pci_probe() */

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index c358e7a07f3faf2abbfff9de4b9e219ae6558e58..882f1f9596dfffa644e624b3a42a120999f06581 100644 (file)
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -311,6 +311,7 @@ static inline void pci_restore_ats_state(struct pci_dev *dev)
 #ifdef CONFIG_PCI_IOV
 int pci_iov_init(struct pci_dev *dev);
 void pci_iov_release(struct pci_dev *dev);
+void pci_iov_remove(struct pci_dev *dev);
 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);
@@ -323,6 +324,9 @@ static inline int pci_iov_init(struct pci_dev *dev)
 }
 static inline void pci_iov_release(struct pci_dev *dev)
 
+{
+}
+static inline void pci_iov_remove(struct pci_dev *dev)
 {
 }
 static inline void pci_restore_iov_state(struct pci_dev *dev)