[PATCH 1/2 V3] PCI: introduce device assignment interface and refactory related code

[Ethan Zhao <ethan.zhao@oracle.com>]

This patch introduces two new device assignment functions

pci_iov_assign_device(),
pci_iov_deassign_device()

along with the existed one

pci_vfs_assigned()

They construct the VFs assignment management interface, used to assign/
deassign device to VM and query the VFs reference counter. instead of
direct manipulation of device flag.

This patch refashioned the related code and make them atomic.

v3: change the naming of device assignment helpers, because they work
for all kind of PCI device, not only SR-IOV (david.vrabel@citrix.com)

v2: reorder the patchset and make it bisectable and atomic, steps clear
between interface defination and implemenation according to the
suggestion from alex.williamson@redhat.com

Signed-off-by: Ethan Zhao <ethan.zhao@oracle.com>
---
 drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c |   17 ++---------------
 drivers/pci/iov.c                                  |   20 ++++++++++++++++++++
 drivers/xen/xen-pciback/pci_stub.c                 |    4 ++--
 include/linux/pci.h                                |    4 ++++
 virt/kvm/assigned-dev.c                            |    2 +-
 virt/kvm/iommu.c                                   |    4 ++--
 6 files changed, 31 insertions(+), 20 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
index 02c11a7..781040e 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
@@ -693,22 +693,9 @@ complete_reset:
 static bool i40e_vfs_are_assigned(struct i40e_pf *pf)
 {
 	struct pci_dev *pdev = pf->pdev;
-	struct pci_dev *vfdev;
-
-	/* loop through all the VFs to see if we own any that are assigned */
-	vfdev = pci_get_device(PCI_VENDOR_ID_INTEL, I40E_DEV_ID_VF , NULL);
-	while (vfdev) {
-		/* if we don't own it we don't care */
-		if (vfdev->is_virtfn && pci_physfn(vfdev) == pdev) {
-			/* if it is assigned we cannot release it */
-			if (vfdev->dev_flags & PCI_DEV_FLAGS_ASSIGNED)
-				return true;
-		}
 
-		vfdev = pci_get_device(PCI_VENDOR_ID_INTEL,
-				       I40E_DEV_ID_VF,
-				       vfdev);
-	}
+	if (pci_vfs_assigned(pdev))
+		return true;
 
 	return false;
 }
diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index de7a747..090f827 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -644,6 +644,26 @@ int pci_vfs_assigned(struct pci_dev *dev)
 EXPORT_SYMBOL_GPL(pci_vfs_assigned);
 
 /**
+ * pci_iov_assign_device - assign device to VM
+ * @pdev: the device to be assigned.
+ */
+void pci_iov_assign_device(struct pci_dev *pdev)
+{
+	pdev->dev_flags |= PCI_DEV_FLAGS_ASSIGNED;
+}
+EXPORT_SYMBOL_GPL(pci_iov_assign_device);
+
+/**
+ * pci_iov_deassign_device - deasign device from VM
+ * @pdev: the device to be deassigned.
+ */
+void pci_iov_deassign_device(struct pci_dev *pdev)
+{
+	pdev->dev_flags &= ~PCI_DEV_FLAGS_ASSIGNED;
+}
+EXPORT_SYMBOL_GPL(pci_iov_deassign_device);
+
+/**
  * 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/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
index 62fcd48..27e00d1 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -133,7 +133,7 @@ static void pcistub_device_release(struct kref *kref)
 	xen_pcibk_config_free_dyn_fields(dev);
 	xen_pcibk_config_free_dev(dev);
 
-	dev->dev_flags &= ~PCI_DEV_FLAGS_ASSIGNED;
+	pci_iov_deassign_device(dev);
 	pci_dev_put(dev);
 
 	kfree(psdev);
@@ -404,7 +404,7 @@ static int pcistub_init_device(struct pci_dev *dev)
 	dev_dbg(&dev->dev, "reset device\n");
 	xen_pcibk_reset_device(dev);
 
-	dev->dev_flags |= PCI_DEV_FLAGS_ASSIGNED;
+	pci_iov_assign_device(dev);
 	return 0;
 
 config_release:
diff --git a/include/linux/pci.h b/include/linux/pci.h
index aab57b4..5ece6d6 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1603,6 +1603,8 @@ 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);
+void pci_iov_assign_device(struct pci_dev *dev);
+void pci_iov_deassign_device(struct pci_dev *dev);
 #else
 static inline int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn)
 { return -ENODEV; }
@@ -1614,6 +1616,8 @@ static inline int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs)
 { return 0; }
 static inline int pci_sriov_get_totalvfs(struct pci_dev *dev)
 { return 0; }
+static inline void pci_iov_assign_device(struct pci_dev *dev) { }
+static inline void pci_iov_deassign_device(struct pci_dev *dev) { }
 #endif
 
 #if defined(CONFIG_HOTPLUG_PCI) || defined(CONFIG_HOTPLUG_PCI_MODULE)
diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
index bf06577..7fac58d 100644
--- a/virt/kvm/assigned-dev.c
+++ b/virt/kvm/assigned-dev.c
@@ -302,7 +302,7 @@ static void kvm_free_assigned_device(struct kvm *kvm,
 	else
 		pci_restore_state(assigned_dev->dev);
 
-	assigned_dev->dev->dev_flags &= ~PCI_DEV_FLAGS_ASSIGNED;
+	pci_iov_deassign_device(assigned_dev->dev);
 
 	pci_release_regions(assigned_dev->dev);
 	pci_disable_device(assigned_dev->dev);
diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
index 0df7d4b..641ee73 100644
--- a/virt/kvm/iommu.c
+++ b/virt/kvm/iommu.c
@@ -194,7 +194,7 @@ int kvm_assign_device(struct kvm *kvm,
 			goto out_unmap;
 	}
 
-	pdev->dev_flags |= PCI_DEV_FLAGS_ASSIGNED;
+	pci_iov_assign_device(pdev);
 
 	dev_info(&pdev->dev, "kvm assign device\n");
 
@@ -220,7 +220,7 @@ int kvm_deassign_device(struct kvm *kvm,
 
 	iommu_detach_device(domain, &pdev->dev);
 
-	pdev->dev_flags &= ~PCI_DEV_FLAGS_ASSIGNED;
+	pci_iov_deassign_device(pdev);
 
 	dev_info(&pdev->dev, "kvm deassign device\n");
 
-- 
1.7.1