Re: [PATCH RFC] pci: Control whether VFs are probed on pci_enable_sriov

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On 01/09/2015 01:25 PM, Bjorn Helgaas wrote:
On Sun, Dec 07, 2014 at 03:08:13PM +0200, Eli Cohen wrote:
Sometimes it is not desirable to probe the virtual fuctions right away,
but rather leave the decision to the host's administrator.

This can save host side resource usage by VF instances which would be
eventually probed to VMs.

Use a parameter to pci_enable_sriov to control that policy, and modify
all current callers such that they retain the same functionality.

Use a one shot flag on struct pci_device which is cleared after the
first probe is ignored so subsequent attempts go through.

Cc: Donald Dutile <ddutile@xxxxxxxxxx>
Signed-off-by: Eli Cohen <eli@xxxxxxxxxxxx>

Seems like we never really reached a consensus here.  Please repost if you
want to continue down this path.

Bjorn

hmmm, seems like I have to increase the power on my nack-phaser.
-dd

---
This approach is used by the mlx5 driver SRIOV implementation, so
sending this to get feedback from the PCI and networking folks.

  drivers/misc/genwqe/card_base.c                      |  2 +-
  drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c    |  2 +-
  drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c      |  2 +-
  drivers/net/ethernet/cisco/enic/enic_main.c          |  2 +-
  drivers/net/ethernet/emulex/benet/be_main.c          |  2 +-
  drivers/net/ethernet/intel/fm10k/fm10k_iov.c         |  2 +-
  drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c   |  2 +-
  drivers/net/ethernet/intel/igb/igb_main.c            |  2 +-
  drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c       |  4 ++--
  drivers/net/ethernet/mellanox/mlx4/main.c            |  2 +-
  drivers/net/ethernet/neterion/vxge/vxge-main.c       |  2 +-
  drivers/net/ethernet/qlogic/qlcnic/qlcnic_sriov_pf.c |  2 +-
  drivers/net/ethernet/sfc/siena_sriov.c               |  2 +-
  drivers/pci/iov.c                                    | 12 +++++++-----
  drivers/pci/pci-driver.c                             | 11 ++++++++---
  drivers/scsi/lpfc/lpfc_init.c                        |  2 +-
  include/linux/pci.h                                  |  5 +++--
  17 files changed, 33 insertions(+), 25 deletions(-)

diff --git a/drivers/misc/genwqe/card_base.c b/drivers/misc/genwqe/card_base.c
index 4cf8f82cfca2..69253ca17506 100644
--- a/drivers/misc/genwqe/card_base.c
+++ b/drivers/misc/genwqe/card_base.c
@@ -1325,7 +1325,7 @@ static int genwqe_sriov_configure(struct pci_dev *dev, int numvfs)

  	if (numvfs > 0) {
  		genwqe_setup_vf_jtimer(cd);
-		rc = pci_enable_sriov(dev, numvfs);
+		rc = pci_enable_sriov(dev, numvfs, 1);
  		if (rc < 0)
  			return rc;
  		return numvfs;
diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c
index c88b20af87df..773b20224a47 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c
@@ -2570,7 +2570,7 @@ int bnx2x_enable_sriov(struct bnx2x *bp)
  	if (rc)
  		return rc;

-	rc = pci_enable_sriov(bp->pdev, req_vfs);
+	rc = pci_enable_sriov(bp->pdev, req_vfs, 1);
  	if (rc) {
  		BNX2X_ERR("pci_enable_sriov failed with %d\n", rc);
  		return rc;
diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c
index 3aea82bb9039..6e8afbfd3eba 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c
@@ -6597,7 +6597,7 @@ static int init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
  sriov:
  #ifdef CONFIG_PCI_IOV
  	if (func < ARRAY_SIZE(num_vf) && num_vf[func] > 0)
-		if (pci_enable_sriov(pdev, num_vf[func]) == 0)
+		if (pci_enable_sriov(pdev, num_vf[func], 1) == 0)
  			dev_info(&pdev->dev,
  				 "instantiated %u virtual functions\n",
  				 num_vf[func]);
diff --git a/drivers/net/ethernet/cisco/enic/enic_main.c b/drivers/net/ethernet/cisco/enic/enic_main.c
index 86ee350e57f0..8a8b1d86f18a 100644
--- a/drivers/net/ethernet/cisco/enic/enic_main.c
+++ b/drivers/net/ethernet/cisco/enic/enic_main.c
@@ -2421,7 +2421,7 @@ static int enic_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
  		pci_read_config_word(pdev, pos + PCI_SRIOV_TOTAL_VF,
  			&enic->num_vfs);
  		if (enic->num_vfs) {
-			err = pci_enable_sriov(pdev, enic->num_vfs);
+			err = pci_enable_sriov(pdev, enic->num_vfs, 1);
  			if (err) {
  				dev_err(dev, "SRIOV enable failed, aborting."
  					" pci_enable_sriov() returned %d\n",
diff --git a/drivers/net/ethernet/emulex/benet/be_main.c b/drivers/net/ethernet/emulex/benet/be_main.c
index dc77ec2bdafd..a96491777ac4 100644
--- a/drivers/net/ethernet/emulex/benet/be_main.c
+++ b/drivers/net/ethernet/emulex/benet/be_main.c
@@ -3274,7 +3274,7 @@ static int be_vf_setup(struct be_adapter *adapter)
  	}

  	if (!old_vfs) {
-		status = pci_enable_sriov(adapter->pdev, adapter->num_vfs);
+		status = pci_enable_sriov(adapter->pdev, adapter->num_vfs, 1);
  		if (status) {
  			dev_err(dev, "SRIOV enable failed\n");
  			adapter->num_vfs = 0;
diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_iov.c b/drivers/net/ethernet/intel/fm10k/fm10k_iov.c
index 060190864238..04a3dc5acc28 100644
--- a/drivers/net/ethernet/intel/fm10k/fm10k_iov.c
+++ b/drivers/net/ethernet/intel/fm10k/fm10k_iov.c
@@ -408,7 +408,7 @@ int fm10k_iov_configure(struct pci_dev *pdev, int num_vfs)
  		 */
  		fm10k_disable_aer_comp_abort(pdev);

-		err = pci_enable_sriov(pdev, num_vfs);
+		err = pci_enable_sriov(pdev, num_vfs, 1);
  		if (err) {
  			dev_err(&pdev->dev,
  				"Enable PCI SR-IOV failed: %d\n", err);
diff --git a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
index 668d860275d6..fe56e09725f2 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
@@ -852,7 +852,7 @@ int i40e_alloc_vfs(struct i40e_pf *pf, u16 num_alloc_vfs)

  	/* Check to see if we're just allocating resources for extant VFs */
  	if (pci_num_vf(pf->pdev) != num_alloc_vfs) {
-		ret = pci_enable_sriov(pf->pdev, num_alloc_vfs);
+		ret = pci_enable_sriov(pf->pdev, num_alloc_vfs, 1);
  		if (ret) {
  			dev_err(&pf->pdev->dev,
  				"Failed to enable SR-IOV, error %d.\n", ret);
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index 3c0221620c9d..da01326ef550 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -2742,7 +2742,7 @@ static int igb_enable_sriov(struct pci_dev *pdev, int num_vfs)

  	/* only call pci_enable_sriov() if no VFs are allocated already */
  	if (!old_vfs) {
-		err = pci_enable_sriov(pdev, adapter->vfs_allocated_count);
+		err = pci_enable_sriov(pdev, adapter->vfs_allocated_count, 1);
  		if (err)
  			goto err_out;
  	}
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
index 04eee7c7b653..74b33483a0d1 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
@@ -149,7 +149,7 @@ void ixgbe_enable_sriov(struct ixgbe_adapter *adapter)
  		 */
  		adapter->num_vfs = min_t(unsigned int, adapter->num_vfs, IXGBE_MAX_VFS_DRV_LIMIT);

-		err = pci_enable_sriov(adapter->pdev, adapter->num_vfs);
+		err = pci_enable_sriov(adapter->pdev, adapter->num_vfs, 1);
  		if (err) {
  			e_err(probe, "Failed to enable PCI sriov: %d\n", err);
  			adapter->num_vfs = 0;
@@ -270,7 +270,7 @@ static int ixgbe_pci_sriov_enable(struct pci_dev *dev, int num_vfs)
  	for (i = 0; i < adapter->num_vfs; i++)
  		ixgbe_vf_configuration(dev, (i | 0x10000000));

-	err = pci_enable_sriov(dev, num_vfs);
+	err = pci_enable_sriov(dev, num_vfs, 1);
  	if (err) {
  		e_dev_warn("Failed to enable PCI sriov: %d\n", err);
  		return err;
diff --git a/drivers/net/ethernet/mellanox/mlx4/main.c b/drivers/net/ethernet/mellanox/mlx4/main.c
index 3044f9e623cb..ae38b556ec13 100644
--- a/drivers/net/ethernet/mellanox/mlx4/main.c
+++ b/drivers/net/ethernet/mellanox/mlx4/main.c
@@ -2350,7 +2350,7 @@ static u64 mlx4_enable_sriov(struct mlx4_dev *dev, struct pci_dev *pdev,
  					 existing_vfs, total_vfs);
  		} else {
  			mlx4_warn(dev, "Enabling SR-IOV with %d VFs\n", total_vfs);
-			err = pci_enable_sriov(pdev, total_vfs);
+			err = pci_enable_sriov(pdev, total_vfs, 1);
  		}
  		if (err) {
  			mlx4_err(dev, "Failed to enable SR-IOV, continuing without SR-IOV (err = %d)\n",
diff --git a/drivers/net/ethernet/neterion/vxge/vxge-main.c b/drivers/net/ethernet/neterion/vxge/vxge-main.c
index cc0485e3c621..c341e73fc68c 100644
--- a/drivers/net/ethernet/neterion/vxge/vxge-main.c
+++ b/drivers/net/ethernet/neterion/vxge/vxge-main.c
@@ -4495,7 +4495,7 @@ vxge_probe(struct pci_dev *pdev, const struct pci_device_id *pre)
  	/* Enable SRIOV mode, if firmware has SRIOV support and if it is a PF */
  	if (is_sriov(function_mode) && !is_sriov_initialized(pdev) &&
  	   (ll_config->intr_type != INTA)) {
-		ret = pci_enable_sriov(pdev, num_vfs);
+		ret = pci_enable_sriov(pdev, num_vfs, 1);
  		if (ret)
  			vxge_debug_ll_config(VXGE_ERR,
  				"Failed in enabling SRIOV mode: %d\n", ret);
diff --git a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_sriov_pf.c b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_sriov_pf.c
index a29538b86edf..b483705a1ef1 100644
--- a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_sriov_pf.c
+++ b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_sriov_pf.c
@@ -570,7 +570,7 @@ static int qlcnic_sriov_pf_enable(struct qlcnic_adapter *adapter, int num_vfs)
  	if (!qlcnic_sriov_enable_check(adapter))
  		return 0;

-	err = pci_enable_sriov(adapter->pdev, num_vfs);
+	err = pci_enable_sriov(adapter->pdev, num_vfs, 1);
  	if (err)
  		qlcnic_sriov_pf_cleanup(adapter);

diff --git a/drivers/net/ethernet/sfc/siena_sriov.c b/drivers/net/ethernet/sfc/siena_sriov.c
index a8bbbad68a88..6804ed04cfcd 100644
--- a/drivers/net/ethernet/sfc/siena_sriov.c
+++ b/drivers/net/ethernet/sfc/siena_sriov.c
@@ -1332,7 +1332,7 @@ int efx_siena_sriov_init(struct efx_nic *efx)

  	/* At this point we must be ready to accept VFDI requests */

-	rc = pci_enable_sriov(efx->pci_dev, efx->vf_count);
+	rc = pci_enable_sriov(efx->pci_dev, efx->vf_count, 1);
  	if (rc)
  		goto fail_pci;

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 4d109c07294a..f6aba5beea78 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -57,7 +57,7 @@ static void virtfn_remove_bus(struct pci_bus *physbus, struct pci_bus *virtbus)
  		pci_remove_bus(virtbus);
  }

-static int virtfn_add(struct pci_dev *dev, int id, int reset)
+static int virtfn_add(struct pci_dev *dev, int id, int reset, int probe)
  {
  	int i;
  	int rc = -ENOMEM;
@@ -85,6 +85,7 @@ static int virtfn_add(struct pci_dev *dev, int id, int reset)
  	virtfn->physfn = pci_dev_get(dev);
  	virtfn->is_virtfn = 1;
  	virtfn->multifunction = 0;
+	virtfn->probe_vf = probe;

  	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
  		res = dev->resource + PCI_IOV_RESOURCES + i;
@@ -170,7 +171,7 @@ static void virtfn_remove(struct pci_dev *dev, int id, int reset)
  	pci_dev_put(dev);
  }

-static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
+static int sriov_enable(struct pci_dev *dev, int nr_virtfn, int probe_vfs)
  {
  	int rc;
  	int i, j;
@@ -255,7 +256,7 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
  		initial = nr_virtfn;

  	for (i = 0; i < initial; i++) {
-		rc = virtfn_add(dev, i, 0);
+		rc = virtfn_add(dev, i, 0, probe_vfs);
  		if (rc)
  			goto failed;
  	}
@@ -558,17 +559,18 @@ int pci_iov_bus_range(struct pci_bus *bus)
   * pci_enable_sriov - enable the SR-IOV capability
   * @dev: the PCI device
   * @nr_virtfn: number of virtual functions to enable
+ * @probe_vfs: in zero, don't probe new VFs, otherwise probe if suitable driver available
   *
   * Returns 0 on success, or negative on failure.
   */
-int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn)
+int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn, int probe_vfs)
  {
  	might_sleep();

  	if (!dev->is_physfn)
  		return -ENOSYS;

-	return sriov_enable(dev, nr_virtfn);
+	return sriov_enable(dev, nr_virtfn, probe_vfs);
  }
  EXPORT_SYMBOL_GPL(pci_enable_sriov);

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 2b3c89425bb5..d5b93339b8a4 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -397,9 +397,14 @@ static int pci_device_probe(struct device *dev)
  	drv = to_pci_driver(dev->driver);
  	pci_dev = to_pci_dev(dev);
  	pci_dev_get(pci_dev);
-	error = __pci_device_probe(drv, pci_dev);
-	if (error)
-		pci_dev_put(pci_dev);
+	if (!pci_dev->is_virtfn || pci_dev->probe_vf) {
+		error = __pci_device_probe(drv, pci_dev);
+		if (error)
+			pci_dev_put(pci_dev);
+	}
+	/* one shot blocking of probe */
+	if (pci_dev->is_virtfn && !pci_dev->probe_vf)
+		pci_dev->probe_vf = 1;

  	return error;
  }
diff --git a/drivers/scsi/lpfc/lpfc_init.c b/drivers/scsi/lpfc/lpfc_init.c
index 0b2c53af85c7..2f81f471b8f3 100644
--- a/drivers/scsi/lpfc/lpfc_init.c
+++ b/drivers/scsi/lpfc/lpfc_init.c
@@ -4797,7 +4797,7 @@ lpfc_sli_probe_sriov_nr_virtfn(struct lpfc_hba *phba, int nr_vfn)
  		return -EINVAL;
  	}

-	rc = pci_enable_sriov(pdev, nr_vfn);
+	rc = pci_enable_sriov(pdev, nr_vfn, 1);
  	if (rc) {
  		lpfc_printf_log(phba, KERN_WARNING, LOG_INIT,
  				"2806 Failed to enable sriov on this device "
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 4c8ac5fcc224..beb2640ba18d 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -373,6 +373,7 @@ struct pci_dev {
  	phys_addr_t rom; /* Physical address of ROM if it's not from the BAR */
  	size_t romlen; /* Length of ROM if it's not from the BAR */
  	char *driver_override; /* Driver name to force a match */
+	int probe_vf; /* probe this device */
  };

  static inline struct pci_dev *pci_physfn(struct pci_dev *dev)
@@ -1655,14 +1656,14 @@ int pci_ext_cfg_avail(void);
  void __iomem *pci_ioremap_bar(struct pci_dev *pdev, int bar);

  #ifdef CONFIG_PCI_IOV
-int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn);
+int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn, int probe_vfs);
  void pci_disable_sriov(struct pci_dev *dev);
  int pci_num_vf(struct pci_dev *dev);
  int pci_vfs_assigned(struct pci_dev *dev);
  int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs);
  int pci_sriov_get_totalvfs(struct pci_dev *dev);
  #else
-static inline int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn)
+static inline int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn, int nr_virt_probe)
  { return -ENODEV; }
  static inline void pci_disable_sriov(struct pci_dev *dev) { }
  static inline int pci_num_vf(struct pci_dev *dev) { return 0; }
--
2.1.3


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