On Wed, Sep 22, 2021 at 04:59:30PM -0500, Bjorn Helgaas wrote:

On Wed, Sep 22, 2021 at 01:38:50PM +0300, Leon Romanovsky wrote:

quoted

From: Jason Gunthorpe <jgg@nvidia.com>

The PCI core uses the VF index internally, often called the vf_id,
during the setup of the VF, eg pci_iov_add_virtfn().

This index is needed for device drivers that implement live migration
for their internal operations that configure/control their VFs.

Specifically, mlx5_vfio_pci driver that is introduced in coming patches
from this series needs it and not the bus/device/function which is
exposed today.

Add pci_iov_vf_id() which computes the vf_id by reversing the math that
was used to create the bus/device/function.

Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

mlx5_core_sriov_set_msix_vec_count() looks like it does basically the
same thing as pci_iov_vf_id() by iterating through VFs until it finds
one with a matching devfn (although it *doesn't* check for a matching
bus number, which seems like a bug).

Maybe that should use pci_iov_vf_id()?

Yes, I gave same comment internally and we decided to simply reduce the
amount of changes in mlx5_core to have less distractions and submit as a
followup. Most likely will add this hunk in v1.

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/sriov.c b/drivers/net/ethernet/mellanox/mlx5/core/sriov.c
index e8185b69ac6c..b66be0b4244a 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/sriov.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/sriov.c

@@ -209,15 +209,8 @@ int mlx5_core_sriov_set_msix_vec_count(struct pci_dev *vf, int msix_vec_count)
        /* Reversed translation of PCI VF function number to the internal
         * function_id, which exists in the name of virtfn symlink.
         */
-       for (id = 0; id < pci_num_vf(pf); id++) {
-               if (!sriov->vfs_ctx[id].enabled)
-                       continue;
-
-               if (vf->devfn == pci_iov_virtfn_devfn(pf, id))
-                       break;
-       }
-
-       if (id == pci_num_vf(pf) || !sriov->vfs_ctx[id].enabled)
+       id = pci_iov_vf_id(vf);
+       if (id < 0 || !sriov->vfs_ctx[id].enabled)
                return -EINVAL;

        return mlx5_set_msix_vec_count(dev, id + 1, msix_vec_count);

Thanks

quoted

---
 drivers/pci/iov.c   | 14 ++++++++++++++
 include/linux/pci.h |  7 ++++++-
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index dafdc652fcd0..e7751fa3fe0b 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c

@@ -33,6 +33,20 @@ int pci_iov_virtfn_devfn(struct pci_dev *dev, int vf_id)
 }
 EXPORT_SYMBOL_GPL(pci_iov_virtfn_devfn);
 
+int pci_iov_vf_id(struct pci_dev *dev)
+{
+	struct pci_dev *pf;
+
+	if (!dev->is_virtfn)
+		return -EINVAL;
+
+	pf = pci_physfn(dev);
+	return (((dev->bus->number << 8) + dev->devfn) -
+		((pf->bus->number << 8) + pf->devfn + pf->sriov->offset)) /
+	       pf->sriov->stride;
+}
+EXPORT_SYMBOL_GPL(pci_iov_vf_id);
+
 /*
  * Per SR-IOV spec sec 3.3.10 and 3.3.11, First VF Offset and VF Stride may
  * change when NumVFs changes.

diff --git a/include/linux/pci.h b/include/linux/pci.h
index cd8aa6fce204..4d6c73506e18 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h

@@ -2153,7 +2153,7 @@ void __iomem *pci_ioremap_wc_bar(struct pci_dev *pdev, int bar);
 #ifdef CONFIG_PCI_IOV
 int pci_iov_virtfn_bus(struct pci_dev *dev, int id);
 int pci_iov_virtfn_devfn(struct pci_dev *dev, int id);
-
+int pci_iov_vf_id(struct pci_dev *dev);
 int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn);
 void pci_disable_sriov(struct pci_dev *dev);
 

@@ -2181,6 +2181,11 @@ static inline int pci_iov_virtfn_devfn(struct pci_dev *dev, int id)
 {
 	return -ENOSYS;
 }
+static inline int pci_iov_vf_id(struct pci_dev *dev)
+{
+	return -ENOSYS;
+}
+

Drop the blank line to match the surrounding stubs.

Sure, thanks

quoted

 static inline int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn)
 { return -ENODEV; }