[PATCH V7 02/11] vpci: add hooks for PCI device assign/de-assign

[Oleksandr Tyshchenko <olekstysh@xxxxxxxxx>]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>

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@xxxxxxxx>
---
Since v6:
- do not pass struct domain to vpci_{assign|deassign}_device as
  pdev->domain can be used
- do not leave the device assigned (pdev->domain == new domain) in case
  vpci_assign_device fails: try to de-assign and if this also fails, then
  crash the domain
- re-work according to the new locking scheme (ASSERTs)
- OT: rebased
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 | 11 +++++++++++
 xen/drivers/vpci/vpci.c       | 31 +++++++++++++++++++++++++++++++
 xen/include/xen/vpci.h        | 15 +++++++++++++++
 4 files changed, 61 insertions(+)

diff --git a/xen/drivers/Kconfig b/xen/drivers/Kconfig
index db94393f47..780490cf8e 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 f93922acc8..56af1dbd97 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -1019,6 +1019,8 @@ static int deassign_device(struct domain *d, uint16_t 
seg, uint8_t bus,
     if ( ret )
         goto out;
 
+    vpci_deassign_device(pdev);
+
     if ( pdev->domain == hardware_domain  )
         pdev->quarantine = false;
 
@@ -1558,6 +1560,7 @@ static int assign_device(struct domain *d, u16 seg, u8 
bus, u8 devfn, u32 flag)
 {
     const struct domain_iommu *hd = dom_iommu(d);
     struct pci_dev *pdev;
+    uint8_t old_devfn;
     int rc = 0;
 
     if ( !is_iommu_enabled(d) )
@@ -1577,6 +1580,8 @@ static int assign_device(struct domain *d, u16 seg, u8 
bus, u8 devfn, u32 flag)
     if ( pdev->broken && d != hardware_domain && d != dom_io )
         goto done;
 
+    vpci_deassign_device(pdev);
+
     rc = pdev_msix_assign(d, pdev);
     if ( rc )
         goto done;
@@ -1594,6 +1599,8 @@ static int assign_device(struct domain *d, u16 seg, u8 
bus, u8 devfn, u32 flag)
                           pci_to_dev(pdev), flag)) )
         goto done;
 
+    old_devfn = devfn;
+
     for ( ; pdev->phantom_stride; rc = 0 )
     {
         devfn += pdev->phantom_stride;
@@ -1603,6 +1610,10 @@ static int assign_device(struct domain *d, u16 seg, u8 
bus, u8 devfn, u32 flag)
                         pci_to_dev(pdev), flag);
     }
 
+    rc = vpci_assign_device(pdev);
+    if ( rc && deassign_device(d, seg, bus, old_devfn) )
+        domain_crash(d);
+
  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 674c9b347d..d187901422 100644
--- a/xen/drivers/vpci/vpci.c
+++ b/xen/drivers/vpci/vpci.c
@@ -92,6 +92,37 @@ 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 pci_dev *pdev)
+{
+    int rc;
+
+    ASSERT(pcidevs_write_locked());
+
+    if ( !has_vpci(pdev->domain) )
+        return 0;
+
+    rc = vpci_add_handlers(pdev);
+    if ( rc )
+        vpci_deassign_device(pdev);
+
+    return rc;
+}
+
+/* Notify vPCI that device is de-assigned from guest. */
+void vpci_deassign_device(struct pci_dev *pdev)
+{
+    ASSERT(pcidevs_write_locked());
+
+    if ( !has_vpci(pdev->domain) )
+        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 7ab39839ff..e5501b9207 100644
--- a/xen/include/xen/vpci.h
+++ b/xen/include/xen/vpci.h
@@ -254,6 +254,21 @@ 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 pci_dev *pdev);
+void vpci_deassign_device(struct pci_dev *pdev);
+#else
+static inline int vpci_assign_device(struct pci_dev *pdev)
+{
+    return 0;
+};
+
+static inline void vpci_deassign_device(struct pci_dev *pdev)
+{
+};
+#endif
+
 #endif
 
 /*
-- 
2.25.1