On Sat, Apr 20, 2013 at 9:31 PM, Jeff Kirsher
<jeffrey.t.kirsher@xxxxxxxxx> wrote:
> On Sat, 2013-04-20 at 02:49 -0700, Jeff Kirsher wrote:
>> From: Alexander Duyck <alexander.h.duyck@xxxxxxxxx>
>>
>> This function is meant to add a helper function that will determine if a PF
>> has any VFs that are currently assigned to a guest. We currently have been
>> implementing this function per driver, and going forward I would like to avoid
>> that by making this function generic and using this helper.
>>
>> Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxx>
>> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@xxxxxxxxx>
>
> Adding linux-pci mailing list and Bjorn to the CC.
>
> Bjorn- David Miller needs a signoff by PCI maintainer.
>
>> ---
>> drivers/pci/iov.c | 41 +++++++++++++++++++++++++++++++++++++++++
>> include/linux/pci.h | 5 +++++
>> 2 files changed, 46 insertions(+)
>>
>> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
>> index ee599f2..fd99720 100644
>> --- a/drivers/pci/iov.c
>> +++ b/drivers/pci/iov.c
>> @@ -729,6 +729,47 @@ int pci_num_vf(struct pci_dev *dev)
>> EXPORT_SYMBOL_GPL(pci_num_vf);
>>
>> /**
>> + * pci_vfs_assigned - returns number of VFs are assigned to a guest
>> + * @dev: the PCI device
>> + *
>> + * Returns number of VFs belonging to this device that are assigned to a guest.
>> + * If device is not a physical function returns -ENODEV.
>> + */
>> +int pci_vfs_assigned(struct pci_dev *dev)
I guess the idea here is to replace be_find_vfs(),
igb_vfs_are_assigned(), ixgbe_vfs_are_assigned(), etc. It does seem
good to reduce duplicated code.
I'm trying to figure out why this is safe -- there's no explicit
synchronization between the iteration through PCI devices looking for
matching VFs and the device assignment/deassignment paths that set or
clear PCI_DEV_FLAGS_ASSIGNED, so on the face of it, it looks like
things could change between calling pci_vfs_assigned() and using the
result to make a decision.
Most of the calls would be in .remove() functions, so maybe there's
some sort of synchronization in that path that makes this safe.
Bjorn
>> +{
>> + struct pci_dev *vfdev;
>> + unsigned int vfs_assigned = 0;
>> + unsigned short dev_id;
>> +
>> + /* only search if we are a PF */
>> + if (!dev->is_physfn)
>> + return -ENODEV;
>> +
>> + /*
>> + * determine the device ID for the VFs, the vendor ID will be the
>> + * same as the PF so there is no need to check for that one
>> + */
>> + pci_read_config_word(dev, dev->sriov->pos + PCI_SRIOV_VF_DID, &dev_id);
>> +
>> + /* loop through all the VFs to see if we own any that are assigned */
>> + vfdev = pci_get_device(dev->vendor, dev_id, NULL);
>> + while (vfdev) {
>> + /*
>> + * It is considered assigned if it is a virtual function with
>> + * our dev as the physical function and the assigned bit is set
>> + */
>> + if (vfdev->is_virtfn && (vfdev->physfn == dev) &&
>> + (vfdev->dev_flags & PCI_DEV_FLAGS_ASSIGNED))
>> + vfs_assigned++;
>> +
>> + vfdev = pci_get_device(dev->vendor, dev_id, vfdev);
>> + }
>> +
>> + return vfs_assigned;
>> +}
>> +EXPORT_SYMBOL_GPL(pci_vfs_assigned);
>> +
>> +/**
>> * pci_sriov_set_totalvfs -- reduce the TotalVFs available
>> * @dev: the PCI PF device
>> * @numvfs: number that should be used for TotalVFs supported
>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>> index 2461033a..03b4d3c 100644
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -1643,6 +1643,7 @@ extern int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn);
>> extern void pci_disable_sriov(struct pci_dev *dev);
>> extern irqreturn_t pci_sriov_migration(struct pci_dev *dev);
>> extern int pci_num_vf(struct pci_dev *dev);
>> +extern int pci_vfs_assigned(struct pci_dev *dev);
>> extern int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs);
>> extern int pci_sriov_get_totalvfs(struct pci_dev *dev);
>> #else
>> @@ -1661,6 +1662,10 @@ static inline int pci_num_vf(struct pci_dev *dev)
>> {
>> return 0;
>> }
>> +static inline int pci_vfs_assigned(struct pci_dev *dev)
>> +{
>> + return 0;
>> +}
>> static inline int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs)
>> {
>> return 0;
>
>
--
To unsubscribe from this list: send the line "unsubscribe linux-pci" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
