[PATCH v4 04/11] 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.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
---
Since v3:
 - remove toolstack roll-back description from the commit message
   as error are to be handled with proper cleanup in Xen itself
 - remove __must_check
 - remove redundant rc check while assigning devices
 - fix redundant CONFIG_HAS_VPCI check for CONFIG_HAS_VPCI_GUEST_SUPPORT
 - use REGISTER_VPCI_INIT machinery to run required steps on device
   init/assign: add run_vpci_init helper
Since v2:
- define CONFIG_HAS_VPCI_GUEST_SUPPORT so dead code is not compiled
  for x86
Since v1:
 - constify struct pci_dev where possible
 - do not open code is_system_domain()
 - extended the commit message
---
 xen/drivers/Kconfig           |  4 +++
 xen/drivers/passthrough/pci.c |  6 ++++
 xen/drivers/vpci/vpci.c       | 57 ++++++++++++++++++++++++++++++-----
 xen/include/xen/vpci.h        | 16 ++++++++++
 4 files changed, 75 insertions(+), 8 deletions(-)

diff --git a/xen/drivers/Kconfig b/xen/drivers/Kconfig
index db94393f47a6..780490cf8e39 100644
--- a/xen/drivers/Kconfig
+++ b/xen/drivers/Kconfig
@@ -15,4 +15,8 @@ source "drivers/video/Kconfig"
 config HAS_VPCI
 	bool
 
+config HAS_VPCI_GUEST_SUPPORT
+	bool
+	depends on HAS_VPCI
+
 endmenu
diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
index a9d31293ac09..529a4f50aa80 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -873,6 +873,10 @@ 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;
 
@@ -1445,6 +1449,8 @@ 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);
     }
 
+    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 d7f033a0811f..5f086398a98c 100644
--- a/xen/drivers/vpci/vpci.c
+++ b/xen/drivers/vpci/vpci.c
@@ -63,11 +63,25 @@ void vpci_remove_device(struct pci_dev *pdev)
     pdev->vpci = NULL;
 }
 
-int vpci_add_handlers(struct pci_dev *pdev)
+static int run_vpci_init(struct pci_dev *pdev)
 {
     unsigned int i;
     int rc = 0;
 
+    for ( i = 0; i < NUM_VPCI_INIT; i++ )
+    {
+        rc = __start_vpci_array[i](pdev);
+        if ( rc )
+            break;
+    }
+
+    return rc;
+}
+
+int vpci_add_handlers(struct pci_dev *pdev)
+{
+    int rc;
+
     if ( !has_vpci(pdev->domain) )
         return 0;
 
@@ -81,18 +95,45 @@ int vpci_add_handlers(struct pci_dev *pdev)
     INIT_LIST_HEAD(&pdev->vpci->handlers);
     spin_lock_init(&pdev->vpci->lock);
 
-    for ( i = 0; i < NUM_VPCI_INIT; i++ )
-    {
-        rc = __start_vpci_array[i](pdev);
-        if ( rc )
-            break;
-    }
-
+    rc = run_vpci_init(pdev);
     if ( rc )
         vpci_remove_device(pdev);
 
     return rc;
 }
+
+#ifdef CONFIG_HAS_VPCI_GUEST_SUPPORT
+/* Notify vPCI that device is assigned to guest. */
+int vpci_assign_device(struct domain *d, struct pci_dev *pdev)
+{
+    int rc;
+
+    /* It only makes sense to assign for hwdom or guest domain. */
+    if ( is_system_domain(d) || !has_vpci(d) )
+        return 0;
+
+    vpci_remove_device_handlers(pdev);
+
+    rc = run_vpci_init(pdev);
+    if ( rc )
+        vpci_deassign_device(d, pdev);
+
+    return rc;
+}
+
+/* Notify vPCI that device is de-assigned from guest. */
+int vpci_deassign_device(struct domain *d, struct pci_dev *pdev)
+{
+    /* It only makes sense to de-assign from hwdom or guest domain. */
+    if ( is_system_domain(d) || !has_vpci(d) )
+        return 0;
+
+    vpci_remove_device_handlers(pdev);
+
+    return 0;
+}
+#endif /* CONFIG_HAS_VPCI_GUEST_SUPPORT */
+
 #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 1883b9d08a70..a016b4197801 100644
--- a/xen/include/xen/vpci.h
+++ b/xen/include/xen/vpci.h
@@ -262,6 +262,22 @@ static inline void vpci_cancel_pending(const struct pci_dev *pdev)
 }
 #endif
 
+#ifdef CONFIG_HAS_VPCI_GUEST_SUPPORT
+/* Notify vPCI that device is assigned/de-assigned to/from guest. */
+int vpci_assign_device(struct domain *d, struct pci_dev *pdev);
+int vpci_deassign_device(struct domain *d, struct pci_dev *pdev);
+#else
+static inline int vpci_assign_device(struct domain *d, struct pci_dev *pdev)
+{
+    return 0;
+};
+
+static inline int vpci_deassign_device(struct domain *d, struct pci_dev *pdev)
+{
+    return 0;
+};
+#endif
+
 #endif
 
 /*
-- 
2.25.1