run_tests: Probe for max-smp

KVM can be configured to only support a few vcpus. ARM and AArch64
currently have a default config of only 4. While it's nice to be
able to write tests that use the maximum recommended, nr-host-cpus,
we can't assume that nr-host-cpus == kvm-max-vcpus. This patch allows
one to put $MAX_SMP in the smp = <num> line of a unittests.cfg file.
That variable will then expand to the number of host cpus, or to the
maximum vcpus allowed by KVM.

[Inspired by a patch from Alex Bennée solving the same issue.]

Signed-off-by: Andrew Jones <drjones@redhat.com>

arm/unittests.cfg

@@ -2,6 +2,7 @@
 # [unittest_name]
 # file = foo.flat # Name of the flat file to be used
 # smp  = 2        # Number of processors the VM will use during this test
+#                 # Use $MAX_SMP to use the maximum the host supports.
 # extra_params = -append <params...> # Additional parameters used
 # arch = arm/arm64                   # Only if test case is specific to one
 # groups = group1 group2 # Used to identify test cases with run_tests -g ...
@@ -32,6 +33,6 @@ groups = selftest
 # Test SMP support
 [selftest-smp]
 file = selftest.flat
-smp = `getconf _NPROCESSORS_CONF`
+smp = $MAX_SMP
 extra_params = -append 'smp'
 groups = selftest

run_tests.sh

@@ -97,4 +97,13 @@ while getopts "g:hv" opt; do
     esac
 done
 
+#
+# Probe for MAX_SMP
+#
+MAX_SMP=$(getconf _NPROCESSORS_CONF)
+while ./$TEST_DIR-run _NO_FILE_4Uhere_ -smp $MAX_SMP \
+		|& grep -q 'exceeds max cpus'; do
+	((--MAX_SMP))
+done
+
 for_each_unittest $config run

scripts/mkstandalone.sh

@@ -94,6 +94,13 @@ qemu="$qemu"
 if [ "\$QEMU" ]; then
 	qemu="\$QEMU"
 fi
+
+cmdline="\`echo '$cmdline' | sed s%$kernel%_NO_FILE_4Uhere_%\`"
+MAX_SMP=\`getconf _NPROCESSORS_CONF\`
+while \$qemu \$cmdline -smp \$MAX_SMP 2>&1 | grep 'exceeds max cpus' > /dev/null; do
+	MAX_SMP=\`expr \$MAX_SMP - 1\`
+done
+
 cmdline="\`echo '$cmdline' | sed s%$kernel%\$bin%\`"
 echo \$qemu $cmdline -smp $smp $opts
 \$qemu \$cmdline -smp $smp $opts

x86/unittests.cfg

@@ -2,6 +2,7 @@
 # [unittest_name]
 # file = foo.flat # Name of the flat file to be used
 # smp = 2 # Number of processors the VM will use during this test
+#         # Use $MAX_SMP to use the maximum the host supports.
 # extra_params = -cpu qemu64,+x2apic # Additional parameters used
 # arch = i386/x86_64 # Only if the test case works only on one of them
 # groups = group1 group2 # Used to identify test cases with run_tests -g ...