vtd: do FLR before xc.domain_destroy()

When we "xm destroy" a guest with assigned devices, in
xen/common/domain.c:domain_kill(), we relinquish guest's memory first,
then invoke domain_destroy() -> complete_domain_destroy() ->
arch_domain_destroy() -> pci_release_devices()/iommu_domain_destroy().

Between relinquish_memory() and domain_destroy(), a device may be
issuing DMA request and access guest's relinquished  memory.

We can do_FLR() to quiesce devices before xc.domain_destroy().

Signed-off-by: Dexuan Cui <dexuan.cui@intel.com>

tools/python/xen/util/pci.py

@@ -40,6 +40,7 @@ DEV_TYPE_PCIe_BRIDGE    = 1
 DEV_TYPE_PCI_BRIDGE     = 2
 DEV_TYPE_PCI            = 3    
 
+PCI_VENDOR_ID = 0x0
 PCI_STATUS = 0x6
 PCI_CLASS_DEVICE = 0x0a
 PCI_CLASS_BRIDGE_PCI = 0x0604
@@ -69,6 +70,11 @@ PCI_PM_CTRL_NO_SOFT_RESET = 0x0004
 PCI_PM_CTRL_STATE_MASK = 0x0003
 PCI_D3hot = 3
 
+VENDOR_INTEL  = 0x8086
+PCI_CAP_ID_VENDOR_SPECIFIC_CAP = 0x09
+PCI_CLASS_ID_USB = 0x0c03
+PCI_USB_FLRCTRL = 0x4
+
 PCI_CAP_ID_AF = 0x13
 PCI_AF_CAPs   = 0x3
 PCI_AF_CAPs_TP_FLR = 0x3
@@ -487,7 +493,7 @@ class PciDevice:
     def do_Dstate_transition(self):
         pos = self.find_cap_offset(PCI_CAP_ID_PM)
         if pos == 0:
-            return 
+            return False
         
         (pci_list, cfg_list) = save_pci_conf_space([self.name])
         
@@ -504,6 +510,31 @@ class PciDevice:
         time.sleep(0.010)
 
         restore_pci_conf_space((pci_list, cfg_list))
+        return True
+
+    def do_vendor_specific_FLR_method(self):
+        pos = self.find_cap_offset(PCI_CAP_ID_VENDOR_SPECIFIC_CAP)
+        if pos == 0:
+            return
+
+        vendor_id = self.pci_conf_read16(PCI_VENDOR_ID)
+        if vendor_id != VENDOR_INTEL:
+            return
+
+        class_id = self.pci_conf_read16(PCI_CLASS_DEVICE)
+        if class_id != PCI_CLASS_ID_USB:
+            return
+
+        (pci_list, cfg_list) = save_pci_conf_space([self.name])
+
+        self.pci_conf_write8(pos + PCI_USB_FLRCTRL, 1)
+        time.sleep(0.010)
+
+        restore_pci_conf_space((pci_list, cfg_list))
+
+    def do_FLR_for_integrated_device(self):
+        if not self.do_Dstate_transition():
+            self.do_vendor_specific_FLR_method()
 
     def find_all_the_multi_functions(self):
         sysfs_mnt = find_sysfs_mnt()
@@ -676,7 +707,7 @@ class PciDevice:
                 restore_pci_conf_space((pci_list, cfg_list))
             else:
                 if self.bus == 0:
-                    self.do_Dstate_transition()
+                    self.do_FLR_for_integrated_device()
                 else:
                     funcs = self.find_all_the_multi_functions()
                     self.devs_check_driver(funcs)
@@ -697,7 +728,7 @@ class PciDevice:
                 restore_pci_conf_space((pci_list, cfg_list))
             else:
                 if self.bus == 0:
-                    self.do_Dstate_transition()
+                    self.do_FLR_for_integrated_device()
                 else:
                     devs = self.find_coassigned_devices(False)
                     # Remove the element 0 which is a bridge

tools/python/xen/xend/XendDomain.py

@@ -419,6 +419,8 @@ class XendDomain:
                 except VmError:
                     log.exception("Unable to recreate domain")
                     try:
+                        xc.domain_pause(domid)
+                        do_FLR(domid)
                         xc.domain_destroy(domid)
                     except:
                         log.exception("Hard destruction of domain failed: %d" %
@@ -1255,6 +1257,8 @@ class XendDomain:
             val = dominfo.destroy()
         else:
             try:
+                xc.domain_pause(int(domid))
+                do_FLR(int(domid))
                 val = xc.domain_destroy(int(domid))
             except ValueError:
                 raise XendInvalidDomain(domid)

tools/python/xen/xend/XendDomainInfo.py

@@ -287,6 +287,28 @@ def dom_get(dom):
         log.trace("domain_getinfo(%d) failed, ignoring: %s", dom, str(err))
     return None
 
+def do_FLR(domid):
+    from xen.xend.server.pciif import parse_pci_name, PciDevice
+    path = '/local/domain/0/backend/pci/%u/0/' % domid
+    num_devs = xstransact.Read(path + 'num_devs');
+    if num_devs is None or num_devs == "":
+        return;
+
+    num_devs = int(xstransact.Read(path + 'num_devs'));
+
+    dev_str_list = []
+    for i in range(num_devs):
+        dev_str = xstransact.Read(path + 'dev-%i' % i)
+        dev_str_list = dev_str_list + [dev_str]
+
+    for dev_str in dev_str_list:
+        (dom, b, d, f) = parse_pci_name(dev_str)
+        try:
+            dev = PciDevice(dom, b, d, f)
+        except Exception, e:
+            raise VmError("pci: failed to locate device and "+
+                    "parse it's resources - "+str(e))
+        dev.do_FLR()
 
 class XendDomainInfo:
     """An object represents a domain.
@@ -2410,6 +2432,8 @@ class XendDomainInfo:
         try:
             if self.domid is not None:
                 xc.domain_destroy_hook(self.domid)
+                xc.domain_pause(self.domid)
+                do_FLR(self.domid)
                 xc.domain_destroy(self.domid)
                 for state in DOM_STATES_OLD:
                     self.info[state] = 0

tools/python/xen/xend/server/DevController.py

@@ -223,12 +223,6 @@ class DevController:
         raise VmError('%s devices may not be reconfigured' % self.deviceClass)
 
 
-    def cleanupDeviceOnDomainDestroy(self, devid):
-        """ Some devices may need special cleanup when the guest domain
-            is destroyed.
-        """
-        return
-
     def destroyDevice(self, devid, force):
         """Destroy the specified device.
 
@@ -245,8 +239,6 @@ class DevController:
 
         dev = self.convertToDeviceNumber(devid)
 
-        self.cleanupDeviceOnDomainDestroy(dev)
-
         # Modify online status /before/ updating state (latter is watched by
         # drivers, so this ordering avoids a race).
         self.writeBackend(dev, 'online', "0")

tools/python/xen/xend/server/pciif.py

@@ -383,10 +383,10 @@ class PciController(DevController):
             if (dev.dev_type == DEV_TYPE_PCIe_ENDPOINT) and not dev.pcie_flr:
                 if dev.bus == 0:
                     # We cope with this case by using the Dstate transition
-                    # method for now.
+                    # method or some vendor specific methods for now.
                     err_msg = 'pci: %s: it is on bus 0, but has no PCIe' +\
                         ' FLR Capability. Will try the Dstate transition'+\
-                        ' method if available.'
+                        ' method or some vendor specific methods if available.'
                     log.warn(err_msg % dev.name)
                 else:
                     funcs = dev.find_all_the_multi_functions()
@@ -404,10 +404,11 @@ class PciController(DevController):
                 if dev.bus == 0 or arch.type == "ia64":
                     if not dev.pci_af_flr:
                         # We cope with this case by using the Dstate transition
-                        # method for now.
+                        # method or some vendor specific methods for now.
                         err_msg = 'pci: %s: it is on bus 0, but has no PCI' +\
                             ' Advanced Capabilities for FLR. Will try the'+\
-                            ' Dstate transition method if available.'
+                            ' Dstate transition method or some vendor' +\
+                            ' specific methods if available.'
                         log.warn(err_msg % dev.name)
                 else:
                     # All devices behind the uppermost PCI/PCI-X bridge must be\
@@ -543,22 +544,6 @@ class PciController(DevController):
 
         return new_num_devs
 
-    def cleanupDeviceOnDomainDestroy(self, devid):
-        num_devs = int(self.readBackend(devid, 'num_devs'))
-        dev_str_list = []
-        for i in range(num_devs):
-            dev_str = self.readBackend(devid, 'dev-%i' % i)
-            dev_str_list = dev_str_list + [dev_str]
-
-        for dev_str in dev_str_list:
-            (dom, b, d, f) = parse_pci_name(dev_str)
-            try:
-                dev = PciDevice(dom, b, d, f)
-            except Exception, e:
-                raise VmError("pci: failed to locate device and "+
-                        "parse it's resources - "+str(e))
-            dev.do_FLR()
-
     def waitForBackend(self,devid):
         return (0, "ok - no hotplug")