[PATCH v6 05/13] 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 v5:
- do not split code into run_vpci_init
- do not check for is_system_domain in vpci_{de}assign_device
- do not use vpci_remove_device_handlers_locked and re-allocate
  pdev->vpci completely
- make vpci_deassign_device void
Since v4:
 - de-assign vPCI from the previous domain on device assignment
 - do not remove handlers in vpci_assign_device as those must not
   exist at that point
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       | 27 +++++++++++++++++++++++++++
 xen/include/xen/vpci.h        | 15 +++++++++++++++
 4 files changed, 52 insertions(+)

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 50dec3bb73d0..88836aab6baf 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -943,6 +943,8 @@ static int deassign_device(struct domain *d, uint16_t seg, uint8_t bus,
     if ( ret )
         goto out;
 
+    vpci_deassign_device(d, pdev);
+
     if ( pdev->domain == hardware_domain  )
         pdev->quarantine = false;
 
@@ -1488,6 +1490,8 @@ static int assign_device(struct domain *d, u16 seg, u8 bus, u8 devfn, u32 flag)
     ASSERT(pdev && (pdev->domain == hardware_domain ||
                     pdev->domain == dom_io));
 
+    vpci_deassign_device(pdev->domain, pdev);
+
     rc = pdev_msix_assign(d, pdev);
     if ( rc )
         goto done;
@@ -1507,6 +1511,8 @@ static int assign_device(struct domain *d, u16 seg, u8 bus, u8 devfn, u32 flag)
                         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 f8a93e61c08f..4e774875fa04 100644
--- a/xen/drivers/vpci/vpci.c
+++ b/xen/drivers/vpci/vpci.c
@@ -99,6 +99,33 @@ int vpci_add_handlers(struct pci_dev *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;
+
+    if ( !has_vpci(d) )
+        return 0;
+
+    rc = vpci_add_handlers(pdev);
+    if ( rc )
+        vpci_deassign_device(d, pdev);
+
+    return rc;
+}
+
+/* Notify vPCI that device is de-assigned from guest. */
+void vpci_deassign_device(struct domain *d, struct pci_dev *pdev)
+{
+    if ( !has_vpci(d) )
+        return;
+
+    vpci_remove_device(pdev);
+}
+#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 f2a7d82ce77b..246307e6f5d5 100644
--- a/xen/include/xen/vpci.h
+++ b/xen/include/xen/vpci.h
@@ -251,6 +251,21 @@ static inline bool __must_check vpci_process_pending(struct vcpu *v)
 }
 #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);
+void 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 void vpci_deassign_device(struct domain *d, struct pci_dev *pdev)
+{
+};
+#endif
+
 #endif
 
 /*
-- 
2.25.1