[PATCH v8 04/13] vpci: add hooks for PCI device assign/de-assign

[Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>]

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 v8:
- removed vpci_deassign_device
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
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 | 21 +++++++++++++++++++++
 xen/drivers/vpci/vpci.c       | 18 ++++++++++++++++++
 xen/include/xen/vpci.h        | 15 +++++++++++++++
 4 files changed, 58 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 6f8692cd9c..265d359704 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -885,6 +885,10 @@ static int deassign_device(struct domain *d, uint16_t seg, 
uint8_t bus,
     if ( ret )
         goto out;
 
+    write_lock(&pdev->domain->pci_lock);
+    vpci_deassign_device(pdev);
+    write_unlock(&pdev->domain->pci_lock);
+
     if ( pdev->domain == hardware_domain  )
         pdev->quarantine = false;
 
@@ -1484,6 +1488,10 @@ 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;
 
+    write_lock(&pdev->domain->pci_lock);
+    vpci_deassign_device(pdev);
+    write_unlock(&pdev->domain->pci_lock);
+
     rc = pdev_msix_assign(d, pdev);
     if ( rc )
         goto done;
@@ -1509,6 +1517,19 @@ static int assign_device(struct domain *d, u16 seg, u8 
bus, u8 devfn, u32 flag)
         rc = iommu_call(hd->platform_ops, assign_device, d, devfn,
                         pci_to_dev(pdev), flag);
     }
+    if ( rc )
+        goto done;
+
+    devfn = pdev->devfn;
+    write_lock(&pdev->domain->pci_lock);
+    rc = vpci_assign_device(pdev);
+    write_unlock(&pdev->domain->pci_lock);
+    if ( rc && deassign_device(d, seg, bus, devfn) )
+    {
+        printk(XENLOG_ERR "%pd: %pp was left partially assigned\n",
+               d, &PCI_SBDF(seg, bus, devfn));
+        domain_crash(d);
+    }
 
  done:
     if ( rc )
diff --git a/xen/drivers/vpci/vpci.c b/xen/drivers/vpci/vpci.c
index a6d2cf8660..a97710a806 100644
--- a/xen/drivers/vpci/vpci.c
+++ b/xen/drivers/vpci/vpci.c
@@ -107,6 +107,24 @@ 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;
+
+    if ( !has_vpci(pdev->domain) )
+        return 0;
+
+    rc = vpci_add_handlers(pdev);
+    if ( rc )
+        vpci_deassign_device(pdev);
+
+    return rc;
+}
+#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 0b8a2a3c74..44296623e1 100644
--- a/xen/include/xen/vpci.h
+++ b/xen/include/xen/vpci.h
@@ -264,6 +264,21 @@ 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);
+#define vpci_deassign_device vpci_remove_device
+#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
 
 /*
-- 
2.41.0