[libvirt] [PATCH 2/3] conf: don't allow connecting upstream-port directly to pce-expander-bus

[Laine Stump]

I apparently misunderstood Marcel's description of what could and
couldn't be plugged into qemu's pxb-pcie controller (known as
pcie-expander-bus in libvirt) - I specifically allowed directly
connecting a pcie-switch-upstream-port, and it turns out that causes
the guest kernel to crash.

This patch forbids such a connection, and updates the xml docs
appropriately.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1361172
---
 docs/formatdomain.html.in | 24 +++++++++++++-----------
 src/conf/domain_addr.c    |  9 +++------
 2 files changed, 16 insertions(+), 17 deletions(-)

diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index 5acb3b9..eddb8dd 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -3346,8 +3346,8 @@
         this expander bus, and bus numbers less than the specified
         value will be available to the next lower expander-bus (or the
         root-bus if there are no lower expander buses). If you do not
-        specify a busNumber, libvirt will find the lowest existing
-        busNumber in all other expander buses (or use 256 if there are
+        specify a busNr, libvirt will find the lowest existing
+        busNr in all other expander buses (or use 256 if there are
         no others) and auto-assign the busNr of that found bus - 2,
         which provides one bus number for the pci-expander-bus and one
         for the pci-bridge that is automatically attached to it (if
@@ -3360,15 +3360,17 @@
           2nd bus-number is just being reserved for the pcie-root-port
           that must necessarily be connected to the bus in order to
           actually plug in an endpoint device. If you intend to plug
-          multiple devices into a pcie-expander-bus, you must instead
-          connect a pcie-switch-upstream-port to the
-          pcie-expander-bus, and multiple pcie-switch-downstream-ports
-          to the pcie-switch-downstream-port, and of course for this
-          to work properly, you will need to decrease the
-          pcie-expander-bus' busNr accordingly so that there are
-          enough unused bus numbers above it to accomodate giving out
-          one bus number for the upstream-port and one for each
-          downstream-port).
+          multiple devices into a pcie-expander-bus, you must connect
+          a pcie-switch-upstream-port to the pcie-root-bus that is
+          plugged into the pcie-expander-bus, and multiple
+          pcie-switch-downstream-ports to the
+          pcie-switch-upstream-port, and of course for this to work
+          properly, you will need to decrease the pcie-expander-bus'
+          busNr accordingly so that there are enough unused bus
+          numbers above it to accomodate giving out one bus number for
+          the upstream-port and one for each downstream-port (in
+          addition to the pcie-root-port and the pcie-expander-bus
+          itself).
         </p>
       </dd>
       <dt><code>node</code></dt>
diff --git a/src/conf/domain_addr.c b/src/conf/domain_addr.c
index 98176e2..faf5a5a 100644
--- a/src/conf/domain_addr.c
+++ b/src/conf/domain_addr.c
@@ -161,7 +161,7 @@ virDomainPCIAddressFlagsCompatible(virPCIDeviceAddressPtr addr,
         }
         return false;
     }
-    return true;
+   return true;
 }
 
 
@@ -291,11 +291,8 @@ virDomainPCIAddressBusSetModel(virDomainPCIAddressBusPtr bus,
         bus->maxSlot = VIR_PCI_ADDRESS_SLOT_LAST;
         break;
     case VIR_DOMAIN_CONTROLLER_MODEL_PCIE_EXPANDER_BUS:
-        /* single slot, no hotplug, only accepts pcie-root-port or
-         * pcie-switch-upstream-port.
-         */
-        bus->flags = (VIR_PCI_CONNECT_TYPE_PCIE_ROOT_PORT
-                      | VIR_PCI_CONNECT_TYPE_PCIE_SWITCH_UPSTREAM_PORT);
+        /* single slot, no hotplug, only accepts pcie-root-port */
+        bus->flags = VIR_PCI_CONNECT_TYPE_PCIE_ROOT_PORT;
         bus->minSlot = 0;
         bus->maxSlot = 0;
         break;
-- 
2.7.4