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s390/pci: Pull search for parent PF out of zpci_iov_setup_virtfn()

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This creates a new zpci_iov_find_parent_pf() function which a future
commit can use to find if a VF has a configured parent PF. Use
zdev->rid instead of zdev->devfn such that the new function can be used
before it has been decided if the RID will be exposed and zdev->devfn is
set. Also handle the hypotheical case that the RID is not available but
there is an otherwise matching zbus.

Fixes: 25f39d3dcb ("s390/pci: Ignore RID for isolated VFs")
Cc: stable@vger.kernel.org
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Niklas Schnelle 2025-02-07 13:30:16 +01:00 • committed by Vasily Gorbik
parent 6166caf3bb
commit 05793884a1
1 changed files with 42 additions and 14 deletions
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56
arch/s390/pci/pci_iov.c
View file

@ -60,18 +60,35 @@ static int zpci_iov_link_virtfn(struct pci_dev *pdev, struct pci_dev *virtfn, in
return 0;
}
int zpci_iov_setup_virtfn(struct zpci_bus *zbus, struct pci_dev *virtfn, int vfn)
/**
* zpci_iov_find_parent_pf - Find the parent PF, if any, of the given function
* @zbus: The bus that the PCI function is on, or would be added on
* @zdev: The PCI function
*
* Finds the parent PF, if it exists and is configured, of the given PCI function
* and increments its refcount. Th PF is searched for on the provided bus so the
* caller has to ensure that this is the correct bus to search. This function may
* be used before adding the PCI function to a zbus.
*
* Return: Pointer to the struct pci_dev of the parent PF or NULL if it not
* found. If the function is not a VF or has no RequesterID information,
* NULL is returned as well.
*/
static struct pci_dev *zpci_iov_find_parent_pf(struct zpci_bus *zbus, struct zpci_dev *zdev)
{
int i, cand_devfn;
struct zpci_dev *zdev;
int i, vfid, devfn, cand_devfn;
struct pci_dev *pdev;
int vfid = vfn - 1; /* Linux' vfid's start at 0 vfn at 1*/
int rc = 0;
if (!zbus->multifunction)
return 0;
/* If the parent PF for the given VF is also configured in the
return NULL;
/* Non-VFs and VFs without RID available don't have a parent */
if (!zdev->vfn || !zdev->rid_available)
return NULL;
/* Linux vfid starts at 0 vfn at 1 */
vfid = zdev->vfn - 1;
devfn = zdev->rid & ZPCI_RID_MASK_DEVFN;
/*
* If the parent PF for the given VF is also configured in the
* instance, it must be on the same zbus.
* We can then identify the parent PF by checking what
* devfn the VF would have if it belonged to that PF using the PF's
@ -85,15 +102,26 @@ int zpci_iov_setup_virtfn(struct zpci_bus *zbus, struct pci_dev *virtfn, int vfn
if (!pdev)
continue;
cand_devfn = pci_iov_virtfn_devfn(pdev, vfid);
if (cand_devfn == virtfn->devfn) {
rc = zpci_iov_link_virtfn(pdev, virtfn, vfid);
/* balance pci_get_slot() */
pci_dev_put(pdev);
break;
}
if (cand_devfn == devfn)
return pdev;
/* balance pci_get_slot() */
pci_dev_put(pdev);
}
}
return NULL;
}
int zpci_iov_setup_virtfn(struct zpci_bus *zbus, struct pci_dev *virtfn, int vfn)
{
struct zpci_dev *zdev = to_zpci(virtfn);
struct pci_dev *pdev_pf;
int rc = 0;
pdev_pf = zpci_iov_find_parent_pf(zbus, zdev);
if (pdev_pf) {
/* Linux' vfids start at 0 while zdev->vfn starts at 1 */
rc = zpci_iov_link_virtfn(pdev_pf, virtfn, zdev->vfn - 1);
pci_dev_put(pdev_pf);
}
return rc;
}