qemu: Don't compare CPU against host for TCG

Right now when building the qemu command line, we try to do various
unconditional validations of the guest CPU against the host CPU. However
this checks are overly applied. The only time we should use the checks
are:

- The user requests host-model/host-passthrough, or

- When KVM is requsted. CPU features requested in TCG mode are always
  emulated by qemu and are independent of the host CPU, so no host CPU
  checks should be performed.

Right now if trying to specify a CPU for arm on an x86 host, it attempts
to do non-sensical validation and falls over.

Switch all the test cases that were intending to test CPU validation to
use KVM, so they continue to test the intended code.

Amend some aarch64 XML tests with a CPU model, to ensure things work
correctly.

(cherry picked from commit cf7fce8f2fd1c930f357fd4ff93ac35f38eb30c6)

src/qemu/qemu_command.c

@@ -6160,6 +6160,8 @@ qemuBuildCpuModelArgStr(virQEMUDriverPtr driver,
     virCPUCompareResult cmp;
     const char *preferred;
     virCapsPtr caps = NULL;
+    bool compareAgainstHost = (def->virtType == VIR_DOMAIN_VIRT_KVM ||
+        def->cpu->mode != VIR_CPU_MODE_CUSTOM);
 
     if (!(caps = virQEMUDriverGetCapabilities(driver, false)))
         goto cleanup;
@@ -6182,30 +6184,33 @@ qemuBuildCpuModelArgStr(virQEMUDriverPtr driver,
         cpuUpdate(cpu, host) < 0)
         goto cleanup;
 
-    cmp = cpuGuestData(host, cpu, &data, &compare_msg);
-    switch (cmp) {
-    case VIR_CPU_COMPARE_INCOMPATIBLE:
-        if (compare_msg) {
-            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
-                           _("guest and host CPU are not compatible: %s"),
-                           compare_msg);
-        } else {
-            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
-                           _("guest CPU is not compatible with host CPU"));
-        }
-        /* fall through */
-    case VIR_CPU_COMPARE_ERROR:
-        goto cleanup;
+    /* For non-KVM, CPU features are emulated, so host compat doesn't matter */
+    if (compareAgainstHost) {
+        cmp = cpuGuestData(host, cpu, &data, &compare_msg);
+        switch (cmp) {
+        case VIR_CPU_COMPARE_INCOMPATIBLE:
+            if (compare_msg) {
+                virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                               _("guest and host CPU are not compatible: %s"),
+                               compare_msg);
+            } else {
+                virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                               _("guest CPU is not compatible with host CPU"));
+            }
+            /* fall through */
+        case VIR_CPU_COMPARE_ERROR:
+            goto cleanup;
 
-    default:
-        break;
+        default:
+            break;
+        }
     }
 
     /* Only 'svm' requires --enable-nesting. The nested
      * 'vmx' patches now simply hook off the CPU features
      */
-    if (def->os.arch == VIR_ARCH_X86_64 ||
-        def->os.arch == VIR_ARCH_I686) {
+    if ((def->os.arch == VIR_ARCH_X86_64 || def->os.arch == VIR_ARCH_I686) &&
+         compareAgainstHost) {
         int hasSVM = cpuHasFeature(data, "svm");
         if (hasSVM < 0)
             goto cleanup;
@@ -6233,16 +6238,23 @@ qemuBuildCpuModelArgStr(virQEMUDriverPtr driver,
         if (VIR_STRDUP(guest->vendor_id, cpu->vendor_id) < 0)
             goto cleanup;
 
-        guest->arch = host->arch;
-        if (cpu->match == VIR_CPU_MATCH_MINIMUM)
-            preferred = host->model;
-        else
-            preferred = cpu->model;
+        if (compareAgainstHost) {
+            guest->arch = host->arch;
+            if (cpu->match == VIR_CPU_MATCH_MINIMUM)
+                preferred = host->model;
+            else
+                preferred = cpu->model;
 
-        guest->type = VIR_CPU_TYPE_GUEST;
-        guest->fallback = cpu->fallback;
-        if (cpuDecode(guest, data, (const char **)cpus, ncpus, preferred) < 0)
-            goto cleanup;
+            guest->type = VIR_CPU_TYPE_GUEST;
+            guest->fallback = cpu->fallback;
+            if (cpuDecode(guest, data,
+                          (const char **)cpus, ncpus, preferred) < 0)
+                goto cleanup;
+        } else {
+            guest->arch = def->os.arch;
+            if (VIR_STRDUP(guest->model, cpu->model) < 0)
+                goto cleanup;
+        }
 
         virBufferAdd(buf, guest->model, -1);
         if (guest->vendor_id)
@@ -6259,7 +6271,7 @@ qemuBuildCpuModelArgStr(virQEMUDriverPtr driver,
     }
 
     ret = 0;
-cleanup:
+ cleanup:
     virObjectUnref(caps);
     VIR_FREE(compare_msg);
     cpuDataFree(data);

tests/qemuxml2argvdata/qemuxml2argv-aarch64-virt-default-nic.args

 LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \
-/usr/bin/qemu-system-aarch64 -S -M virt -m 1024 -smp 1 -nographic \
+/usr/bin/qemu-system-aarch64 -S -M virt -cpu cortex-a53 \
+-m 1024 -smp 1 -nographic \
 -nodefconfig -nodefaults -monitor unix:/tmp/test-monitor,server,nowait \
 -boot c -kernel /aarch64.kernel -initrd /aarch64.initrd -append console=ttyAMA0 \
 -usb -device virtio-net-device,vlan=0,id=net0,mac=52:54:00:09:a4:37 \

tests/qemuxml2argvdata/qemuxml2argv-aarch64-virt-default-nic.xml

@@ -7,6 +7,9 @@
   <features>
     <acpi/>
   </features>
+  <cpu match='exact'>
+    <model>cortex-a53</model>
+  </cpu>
   <os>
     <type arch="aarch64" machine="virt">hvm</type>
     <kernel>/aarch64.kernel</kernel>

tests/qemuxml2argvdata/qemuxml2argv-aarch64-virt-virtio.args

 LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \
-/usr/bin/qemu-system-aarch64 -S -M virt -m 1024 -smp 1 -nographic \
+/usr/bin/qemu-system-aarch64 -S -M virt -cpu cortex-a53 \
+-m 1024 -smp 1 -nographic \
 -nodefconfig -nodefaults -monitor unix:/tmp/test-monitor,server,nowait \
 -boot c -kernel /aarch64.kernel -initrd /aarch64.initrd -append \
 'earlyprintk console=ttyAMA0,115200n8 rw root=/dev/vda rootwait' \

tests/qemuxml2argvdata/qemuxml2argv-aarch64-virt-virtio.xml

@@ -16,6 +16,9 @@
     <apic/>
     <pae/>
   </features>
+  <cpu match='exact'>
+    <model>cortex-a53</model>
+  </cpu>
   <clock offset="utc"/>
   <on_poweroff>destroy</on_poweroff>
   <on_reboot>restart</on_reboot>

tests/qemuxml2argvdata/qemuxml2argv-cpu-exact1.args

 LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \
-/usr/bin/qemu -S -M pc \
+/usr/bin/qemu-kvm -S -M pc \
 -cpu qemu64,-svm,-lm,-nx,-syscall,-clflush,-pse36,-mca -m 214 -smp 6 \
 -nographic -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot n -usb -net \
 none -serial none -parallel none

tests/qemuxml2argvdata/qemuxml2argv-cpu-exact1.xml

-<domain type='qemu'>
+<domain type='kvm'>
   <name>QEMUGuest1</name>
   <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
   <memory unit='KiB'>219100</memory>
@@ -23,6 +23,6 @@
   <on_reboot>restart</on_reboot>
   <on_crash>destroy</on_crash>
   <devices>
-      <emulator>/usr/bin/qemu</emulator>
+      <emulator>/usr/bin/qemu-kvm</emulator>
   </devices>
 </domain>

tests/qemuxml2argvdata/qemuxml2argv-cpu-exact2-nofallback.args

 LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \
-/usr/bin/qemu -S -M pc \
+/usr/bin/qemu-kvm -S -M pc \
 -cpu core2duo,+lahf_lm,+3dnowext,+xtpr,+ds_cpl,+tm,+ht,+ds,-nx -m 214 -smp 6 \
 -nographic -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot n -usb -net \
 none -serial none -parallel none

tests/qemuxml2argvdata/qemuxml2argv-cpu-exact2-nofallback.xml

-<domain type='qemu'>
+<domain type='kvm'>
   <name>QEMUGuest1</name>
   <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
   <memory unit='KiB'>219100</memory>
@@ -30,6 +30,6 @@
   <on_reboot>restart</on_reboot>
   <on_crash>destroy</on_crash>
   <devices>
-      <emulator>/usr/bin/qemu</emulator>
+      <emulator>/usr/bin/qemu-kvm</emulator>
   </devices>
 </domain>

tests/qemuxml2argvdata/qemuxml2argv-cpu-exact2.args

 LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \
-/usr/bin/qemu -S -M pc \
+/usr/bin/qemu-kvm -S -M pc \
 -cpu core2duo,+lahf_lm,+3dnowext,+xtpr,+ds_cpl,+tm,+ht,+ds,-nx -m 214 -smp 6 \
 -nographic -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot n -usb -net \
 none -serial none -parallel none

tests/qemuxml2argvdata/qemuxml2argv-cpu-exact2.xml

-<domain type='qemu'>
+<domain type='kvm'>
   <name>QEMUGuest1</name>
   <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
   <memory unit='KiB'>219100</memory>
@@ -30,6 +30,6 @@
   <on_reboot>restart</on_reboot>
   <on_crash>destroy</on_crash>
   <devices>
-      <emulator>/usr/bin/qemu</emulator>
+      <emulator>/usr/bin/qemu-kvm</emulator>
   </devices>
 </domain>

tests/qemuxml2argvdata/qemuxml2argv-cpu-fallback.args

@@ -3,7 +3,7 @@ PATH=/bin \
 HOME=/home/test \
 USER=test \
 LOGNAME=test QEMU_AUDIO_DRV=none \
-/usr/bin/qemu \
+/usr/bin/qemu-kvm \
 -S \
 -M pc \
 -cpu Penryn,-sse4.1 \

tests/qemuxml2argvdata/qemuxml2argv-cpu-fallback.xml

-<domain type='qemu'>
+<domain type='kvm'>
   <name>QEMUGuest1</name>
   <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
   <memory unit='KiB'>219100</memory>
@@ -20,6 +20,6 @@
   <on_reboot>restart</on_reboot>
   <on_crash>destroy</on_crash>
   <devices>
-      <emulator>/usr/bin/qemu</emulator>
+      <emulator>/usr/bin/qemu-kvm</emulator>
   </devices>
 </domain>

tests/qemuxml2argvdata/qemuxml2argv-cpu-minimum1.args

 LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \
-/usr/bin/qemu -S -M pc \
+/usr/bin/qemu-kvm -S -M pc \
 -cpu core2duo,+lahf_lm,+xtpr,+cx16,+tm2,+est,+vmx,+ds_cpl,+pbe,+tm,+ht,+ss,\
 +acpi,+ds -m 214 -smp 6 -nographic -monitor unix:/tmp/test-monitor,server,\
 nowait -no-acpi -boot n -usb -net none -serial none -parallel none

tests/qemuxml2argvdata/qemuxml2argv-cpu-minimum1.xml

-<domain type='qemu'>
+<domain type='kvm'>
   <name>QEMUGuest1</name>
   <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
   <memory unit='KiB'>219100</memory>
@@ -16,6 +16,6 @@
   <on_reboot>restart</on_reboot>
   <on_crash>destroy</on_crash>
   <devices>
-      <emulator>/usr/bin/qemu</emulator>
+      <emulator>/usr/bin/qemu-kvm</emulator>
   </devices>
 </domain>

tests/qemuxml2argvdata/qemuxml2argv-cpu-minimum2.args

 LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \
-/usr/bin/qemu -S -M pc \
+/usr/bin/qemu-kvm -S -M pc \
 -cpu core2duo,+lahf_lm,+xtpr,+cx16,+tm2,+est,+vmx,+ds_cpl,+pbe,+tm,+ht,+ss,\
 +acpi,+ds,-lm,-nx,-syscall -m 214 -smp 6 -nographic -monitor \
 unix:/tmp/test-monitor,server,nowait -no-acpi -boot n -usb -net none -serial none \

tests/qemuxml2argvdata/qemuxml2argv-cpu-minimum2.xml

-<domain type='qemu'>
+<domain type='kvm'>
   <name>QEMUGuest1</name>
   <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
   <memory unit='KiB'>219100</memory>
@@ -20,6 +20,6 @@
   <on_reboot>restart</on_reboot>
   <on_crash>destroy</on_crash>
   <devices>
-      <emulator>/usr/bin/qemu</emulator>
+      <emulator>/usr/bin/qemu-kvm</emulator>
   </devices>
 </domain>

tests/qemuxml2argvdata/qemuxml2argv-cpu-nofallback.xml

-<domain type='qemu'>
+<domain type='kvm'>
   <name>QEMUGuest1</name>
   <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
   <memory unit='KiB'>219100</memory>

tests/qemuxml2argvdata/qemuxml2argv-cpu-strict1.args

 LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \
-/usr/bin/qemu -S -M pc \
+/usr/bin/qemu-kvm -S -M pc \
 -cpu core2duo,+lahf_lm,+3dnowext,+xtpr,+est,+vmx,+ds_cpl,+tm,+ht,+acpi,+ds,-nx \
 -m 214 -smp 6 -nographic -monitor unix:/tmp/test-monitor,server,nowait \
 -no-acpi -boot n -usb -net none -serial none -parallel none

tests/qemuxml2argvdata/qemuxml2argv-cpu-strict1.xml

-<domain type='qemu'>
+<domain type='kvm'>
   <name>QEMUGuest1</name>
   <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
   <memory unit='KiB'>219100</memory>
@@ -33,6 +33,6 @@
   <on_reboot>restart</on_reboot>
   <on_crash>destroy</on_crash>
   <devices>
-      <emulator>/usr/bin/qemu</emulator>
+      <emulator>/usr/bin/qemu-kvm</emulator>
   </devices>
 </domain>

tests/qemuxml2argvdata/qemuxml2argv-graphics-spice-timeout.args

 LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=spice \
-/usr/bin/qemu -S -M pc -cpu core2duo,+lahf_lm,+xtpr,+cx16,+tm2,\
+/usr/bin/qemu-kvm -S -M pc -cpu core2duo,+lahf_lm,+xtpr,+cx16,+tm2,\
 +est,+vmx,+ds_cpl,+pbe,+tm,+ht,+ss,+acpi,+ds \
 -m 1024 -smp 2 -nodefaults -monitor unix:/tmp/test-monitor,server,nowait \
 -boot dc -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x6 \

tests/qemuxml2argvdata/qemuxml2argv-graphics-spice-timeout.xml

-<domain type='qemu'>
+<domain type='kvm'>
   <name>f14</name>
   <uuid>553effab-b5e1-2d80-dfe3-da4344826c43</uuid>
   <memory unit='KiB'>1048576</memory>
@@ -38,7 +38,7 @@
   <on_reboot>restart</on_reboot>
   <on_crash>restart</on_crash>
   <devices>
-    <emulator>/usr/bin/qemu</emulator>
+    <emulator>/usr/bin/qemu-kvm</emulator>
     <disk type='file' device='disk'>
       <driver name='qemu' type='qcow2'/>
       <source file='/var/lib/libvirt/images/f14.img'/>

tests/qemuxml2argvdata/qemuxml2argv-pseries-cpu-exact.args

 LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test \
-/usr/bin/qemu-system-ppc64 -S -M pseries -cpu POWER7_v2.3 -m 512 -smp 1 -nographic \
--nodefconfig -nodefaults \
+QEMU_AUDIO_DRV=none /usr/bin/qemu-system-ppc64 -S -M pseries -cpu POWER7_v2.3 \
+-m 512 -smp 1 -nographic -nodefconfig -nodefaults \
 -chardev socket,id=charmonitor,path=/tmp/test-monitor,server,nowait \
 -mon chardev=charmonitor,id=monitor,mode=readline -no-acpi -boot c -usb \
 -chardev pty,id=charserial0 \

tests/qemuxml2argvtest.c

@@ -933,7 +933,7 @@ mymain(void)
             QEMU_CAPS_DEVICE, QEMU_CAPS_SPICE,
             QEMU_CAPS_DEVICE_QXL);
     DO_TEST("graphics-spice-timeout",
-            QEMU_CAPS_DRIVE,
+            QEMU_CAPS_KVM, QEMU_CAPS_DRIVE,
             QEMU_CAPS_VGA, QEMU_CAPS_VGA_QXL,
             QEMU_CAPS_DEVICE, QEMU_CAPS_SPICE,
             QEMU_CAPS_DEVICE_QXL_VGA);
@@ -1208,14 +1208,14 @@ mymain(void)
     DO_TEST("cpu-topology1", QEMU_CAPS_SMP_TOPOLOGY);
     DO_TEST("cpu-topology2", QEMU_CAPS_SMP_TOPOLOGY);
     DO_TEST("cpu-topology3", NONE);
-    DO_TEST("cpu-minimum1", NONE);
-    DO_TEST("cpu-minimum2", NONE);
-    DO_TEST("cpu-exact1", NONE);
-    DO_TEST("cpu-exact2", NONE);
-    DO_TEST("cpu-exact2-nofallback", NONE);
-    DO_TEST("cpu-fallback", NONE);
-    DO_TEST_FAILURE("cpu-nofallback", NONE);
-    DO_TEST("cpu-strict1", NONE);
+    DO_TEST("cpu-minimum1", QEMU_CAPS_KVM);
+    DO_TEST("cpu-minimum2", QEMU_CAPS_KVM);
+    DO_TEST("cpu-exact1", QEMU_CAPS_KVM);
+    DO_TEST("cpu-exact2", QEMU_CAPS_KVM);
+    DO_TEST("cpu-exact2-nofallback", QEMU_CAPS_KVM);
+    DO_TEST("cpu-fallback", QEMU_CAPS_KVM);
+    DO_TEST_FAILURE("cpu-nofallback", QEMU_CAPS_KVM);
+    DO_TEST("cpu-strict1", QEMU_CAPS_KVM);
     DO_TEST("cpu-numa1", NONE);
     DO_TEST("cpu-numa2", QEMU_CAPS_SMP_TOPOLOGY);
     DO_TEST_PARSE_ERROR("cpu-numa3", NONE);
@@ -1303,7 +1303,8 @@ mymain(void)
     DO_TEST("pseries-usb-kbd", QEMU_CAPS_PCI_OHCI,
             QEMU_CAPS_DEVICE_USB_KBD, QEMU_CAPS_CHARDEV,
             QEMU_CAPS_DEVICE, QEMU_CAPS_NODEFCONFIG);
-    DO_TEST_FAILURE("pseries-cpu-exact", QEMU_CAPS_CHARDEV, QEMU_CAPS_DEVICE, QEMU_CAPS_NODEFCONFIG);
+    DO_TEST("pseries-cpu-exact", QEMU_CAPS_CHARDEV, QEMU_CAPS_DEVICE,
+            QEMU_CAPS_NODEFCONFIG);
     DO_TEST("disk-ide-drive-split",
             QEMU_CAPS_DRIVE, QEMU_CAPS_DEVICE, QEMU_CAPS_NODEFCONFIG,
             QEMU_CAPS_IDE_CD);

tests/qemuxml2xmloutdata/qemuxml2xmlout-graphics-spice-timeout.xml

-<domain type='qemu'>
+<domain type='kvm'>
   <name>f14</name>
   <uuid>553effab-b5e1-2d80-dfe3-da4344826c43</uuid>
   <memory unit='KiB'>1048576</memory>
@@ -38,7 +38,7 @@
   <on_reboot>restart</on_reboot>
   <on_crash>restart</on_crash>
   <devices>
-    <emulator>/usr/bin/qemu</emulator>
+    <emulator>/usr/bin/qemu-kvm</emulator>
     <disk type='file' device='disk'>
       <driver name='qemu' type='qcow2'/>
       <source file='/var/lib/libvirt/images/f14.img'/>