[PATCH v2 02/11] vpci: Add hooks for PCI device assign/de-assign

[Oleksandr Andrushchenko <andr2000@gmail.com>]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

When a PCI device gets assigned/de-assigned some work on vPCI side needs
to be done for that device. Introduce a pair of hooks so vPCI can handle
that.

Please note, that in the current design the error path is handled by
the toolstack via XEN_DOMCTL_assign_device/XEN_DOMCTL_deassign_device,
so this is why it is acceptable not to de-assign devices if vPCI's
assign fails, e.g. the roll back will be handled on deassign_device when
it is called by the toolstack.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

---
Since v1:
 - constify struct pci_dev where possible
 - do not open code is_system_domain()
 - extended the commit message
---
 xen/drivers/passthrough/pci.c |  9 +++++++++
 xen/drivers/vpci/vpci.c       | 21 +++++++++++++++++++++
 xen/include/xen/vpci.h        | 18 ++++++++++++++++++
 3 files changed, 48 insertions(+)

diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
index fc3469bc12dc..e1da283d73ad 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -872,6 +872,10 @@ static int deassign_device(struct domain *d, uint16_t seg, uint8_t bus,
     if ( ret )
         goto out;
 
+    ret = vpci_deassign_device(d, pdev);
+    if ( ret )
+        goto out;
+
     if ( pdev->domain == hardware_domain  )
         pdev->quarantine = false;
 
@@ -1431,6 +1435,11 @@ static int assign_device(struct domain *d, u16 seg, u8 bus, u8 devfn, u32 flag)
         rc = hd->platform_ops->assign_device(d, devfn, pci_to_dev(pdev), flag);
     }
 
+    if ( rc )
+        goto done;
+
+    rc = vpci_assign_device(d, pdev);
+
  done:
     if ( rc )
         printk(XENLOG_G_WARNING "%pd: assign (%pp) failed (%d)\n",
diff --git a/xen/drivers/vpci/vpci.c b/xen/drivers/vpci/vpci.c
index 1666402d55b8..a8fed3d2c42e 100644
--- a/xen/drivers/vpci/vpci.c
+++ b/xen/drivers/vpci/vpci.c
@@ -86,6 +86,27 @@ int __hwdom_init vpci_add_handlers(struct pci_dev *pdev)
 
     return rc;
 }
+
+/* Notify vPCI that device is assigned to guest. */
+int vpci_assign_device(struct domain *d, const struct pci_dev *dev)
+{
+    /* It only makes sense to assign for hwdom or guest domain. */
+    if ( is_system_domain(d) || !has_vpci(d) )
+        return 0;
+
+    return 0;
+}
+
+/* Notify vPCI that device is de-assigned from guest. */
+int vpci_deassign_device(struct domain *d, const struct pci_dev *dev)
+{
+    /* It only makes sense to de-assign from hwdom or guest domain. */
+    if ( is_system_domain(d) || !has_vpci(d) )
+        return 0;
+
+    return 0;
+}
+
 #endif /* __XEN__ */
 
 static int vpci_register_cmp(const struct vpci_register *r1,
diff --git a/xen/include/xen/vpci.h b/xen/include/xen/vpci.h
index 2e910d0b1f90..b9485b2aea1b 100644
--- a/xen/include/xen/vpci.h
+++ b/xen/include/xen/vpci.h
@@ -26,6 +26,12 @@ typedef int vpci_register_init_t(struct pci_dev *dev);
 /* Add vPCI handlers to device. */
 int __must_check vpci_add_handlers(struct pci_dev *dev);
 
+/* Notify vPCI that device is assigned/de-assigned to/from guest. */
+int __must_check vpci_assign_device(struct domain *d,
+                                    const struct pci_dev *dev);
+int __must_check vpci_deassign_device(struct domain *d,
+                                      const struct pci_dev *dev);
+
 /* Remove all handlers and free vpci related structures. */
 void vpci_remove_device(struct pci_dev *pdev);
 /* Remove all handlers for the device given. */
@@ -220,6 +226,18 @@ static inline int vpci_add_handlers(struct pci_dev *pdev)
     return 0;
 }
 
+static inline int vpci_assign_device(struct domain *d,
+                                     const struct pci_dev *dev)
+{
+    return 0;
+};
+
+static inline int vpci_deassign_device(struct domain *d,
+                                       const struct pci_dev *dev)
+{
+    return 0;
+};
+
 static inline void vpci_dump_msi(void) { }
 
 static inline uint32_t vpci_read(pci_sbdf_t sbdf, unsigned int reg,
-- 
2.25.1