qemu: assign correct type of PCI address for vhost-scsi when using pcie-root

Commit 10c73bf1 fixed a bug that I had introduced back in commit
70249927 - if a vhost-scsi device had no manually assigned PCI
address, one wouldn't be assigned automatically. There was a slight
problem with the logic of the fix though - in the case of domains with
pcie-root (e.g. those with a q35 machinetype),
qemuDomainDeviceCalculatePCIConnectFlags() will attempt to determine
if the host-side PCI device is Express or legacy by examining sysfs
based on the host-side PCI address stored in
hostdev->source.subsys.u.pci.addr, but that part of the union is only
valid for PCI hostdevs, *not* for SCSI hostdevs. So we end up trying
to read sysfs for some probably-non-existent device, which fails, and
the function virPCIDeviceIsPCIExpress() returns failure (-1).

By coincidence, the return value is being examined as a boolean, and
since -1 is true, we still end up assigning the vhost-scsi device to
an Express slot, but that is just by chance (and could fail in the
case that the gibberish in the "hostside PCI address" was the address
of a real device that happened to be legacy PCI).

Since (according to Paolo Bonzini) vhost-scsi devices appear just like
virtio-scsi devices in the guest, they should follow the same rules as
virtio devices when deciding whether they should be placed in an
Express or a legacy slot. That's accomplished in this patch by
returning early with virtioFlags, rather than erroneously using
hostdev->source.subsys.u.pci.addr. It also adds a test case for PCIe
to assure it doesn't get broken in the future.

src/qemu/qemu_domain_address.c

@@ -656,6 +656,13 @@ qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev,
         if (hostdev->source.subsys.type == VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_MDEV)
             return pcieFlags;
 
+        /* according to pbonzini, from the guest PoV vhost-scsi devices
+         * are the same as virtio-scsi, so they should use virtioFlags
+         * (same as virtio-scsi) to determine Express vs. legacy placement
+         */
+        if (hostdev->source.subsys.type == VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_SCSI_HOST)
+            return virtioFlags;
+
         if (!(pciDev = virPCIDeviceNew(hostAddr->domain,
                                        hostAddr->bus,
                                        hostAddr->slot,

tests/qemuxml2argvdata/hostdev-scsi-vhost-scsi-pcie.args

@@ -0,0 +1,25 @@
+LC_ALL=C \
+PATH=/bin \
+HOME=/home/test \
+USER=test \
+LOGNAME=test \
+QEMU_AUDIO_DRV=none \
+/usr/bin/qemu-system-x86_64 \
+-name QEMUGuest2 \
+-S \
+-M pc-q35-2.7 \
+-m 214 \
+-smp 1,sockets=1,cores=1,threads=1 \
+-uuid c7a5fdbd-edaf-9466-926a-d65c16db1809 \
+-nographic \
+-nodefaults \
+-chardev socket,id=charmonitor,path=/tmp/lib/domain--1-QEMUGuest2/monitor.sock,\
+server,nowait \
+-mon chardev=charmonitor,id=monitor,mode=readline \
+-no-acpi \
+-boot c \
+-device pcie-root-port,port=0x10,chassis=1,id=pci.1,bus=pcie.0,\
+multifunction=on,addr=0x2 \
+-device pcie-root-port,port=0x11,chassis=2,id=pci.2,bus=pcie.0,addr=0x2.0x1 \
+-device vhost-scsi-pci,wwpn=naa.5123456789abcde0,vhostfd=3,id=hostdev0,\
+bus=pci.1,addr=0x0

tests/qemuxml2argvdata/hostdev-scsi-vhost-scsi-pcie.xml

@@ -0,0 +1,23 @@
+<domain type='kvm'>
+  <name>QEMUGuest2</name>
+  <uuid>c7a5fdbd-edaf-9466-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219100</memory>
+  <currentMemory unit='KiB'>219100</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='x86_64' machine='pc-q35-2.7'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-x86_64</emulator>
+    <controller type='usb' index='0' model='none'/>
+    <hostdev mode='subsystem' type='scsi_host' managed='no'>
+      <source protocol='vhost' wwpn='naa.5123456789abcde0'/>
+    </hostdev>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2argvtest.c

@@ -2473,6 +2473,13 @@ mymain(void)
     DO_TEST("hostdev-scsi-vhost-scsi-pci",
             QEMU_CAPS_VIRTIO_SCSI, QEMU_CAPS_DEVICE_VHOST_SCSI,
             QEMU_CAPS_DEVICE_SCSI_GENERIC);
+    DO_TEST("hostdev-scsi-vhost-scsi-pcie",
+            QEMU_CAPS_KVM,
+            QEMU_CAPS_VIRTIO_SCSI, QEMU_CAPS_DEVICE_VHOST_SCSI,
+            QEMU_CAPS_DEVICE_SCSI_GENERIC,
+            QEMU_CAPS_PCI_MULTIFUNCTION,
+            QEMU_CAPS_DEVICE_PCIE_ROOT_PORT,
+            QEMU_CAPS_VIRTIO_PCI_DISABLE_LEGACY);
 
     DO_TEST("mlock-on", QEMU_CAPS_REALTIME_MLOCK);
     DO_TEST_FAILURE("mlock-on", NONE);

tests/qemuxml2xmloutdata/hostdev-scsi-vhost-scsi-pcie.xml

@@ -0,0 +1,40 @@
+<domain type='kvm'>
+  <name>QEMUGuest2</name>
+  <uuid>c7a5fdbd-edaf-9466-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219100</memory>
+  <currentMemory unit='KiB'>219100</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='x86_64' machine='pc-q35-2.7'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-x86_64</emulator>
+    <controller type='usb' index='0' model='none'/>
+    <controller type='sata' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
+    </controller>
+    <controller type='pci' index='0' model='pcie-root'/>
+    <controller type='pci' index='1' model='pcie-root-port'>
+      <model name='pcie-root-port'/>
+      <target chassis='1' port='0x10'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0' multifunction='on'/>
+    </controller>
+    <controller type='pci' index='2' model='pcie-root-port'>
+      <model name='pcie-root-port'/>
+      <target chassis='2' port='0x11'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x1'/>
+    </controller>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <hostdev mode='subsystem' type='scsi_host' managed='no'>
+      <source protocol='vhost' wwpn='naa.5123456789abcde0'/>
+      <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
+    </hostdev>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2xmltest.c

@@ -1109,6 +1109,13 @@ mymain(void)
     DO_TEST("hostdev-scsi-vhost-scsi-pci",
             QEMU_CAPS_VIRTIO_SCSI, QEMU_CAPS_DEVICE_VHOST_SCSI,
             QEMU_CAPS_DEVICE_SCSI_GENERIC);
+    DO_TEST("hostdev-scsi-vhost-scsi-pcie",
+            QEMU_CAPS_KVM,
+            QEMU_CAPS_VIRTIO_SCSI, QEMU_CAPS_DEVICE_VHOST_SCSI,
+            QEMU_CAPS_DEVICE_SCSI_GENERIC,
+            QEMU_CAPS_PCI_MULTIFUNCTION,
+            QEMU_CAPS_DEVICE_PCIE_ROOT_PORT,
+            QEMU_CAPS_VIRTIO_PCI_DISABLE_LEGACY);
     DO_TEST("hostdev-scsi-lsi",
             QEMU_CAPS_VIRTIO_SCSI, QEMU_CAPS_SCSI_LSI,
             QEMU_CAPS_DEVICE_SCSI_GENERIC);