In one of my rcutorture tests the TSC clocksource got marked unstable
due to a large difference in the TSC value. I'm not sure if the guest
run for a long time with disabled interrupts or if the host was very
busy and didn't schedule the guest for some time.
I took a look on the qemu/KVM options and decided to update the options:
- Use kvm{32|64} as CPU. We could probably use `host' (like ARM does)
for maximum available features but since we don't run any userland I'm
not sure if it makes any difference.
- Drop the "noapic" option, enable TSC deadline timer. There is no
history why the APIC was disabled, I see no reason for it. The
deadline timer is probably "nicer".
- Additional config options. It ensures that the kernel knowns that it
runs as a kvm guest and can use virt devices like the kvm-clock as
clocksource. The kvm-clock was the main motivation here.
- I didn't add a random HW device. It would make the random device ready
earlier (not it doesn't complete the initialisation at all) but I
doubt that there is any need for this.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
tools/testing/selftests/rcutorture/bin/functions.sh | 13 ++++++++++++-
.../selftests/rcutorture/configs/rcu/CFcommon | 4 ++++
2 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/rcutorture/bin/functions.sh b/tools/testing/selftests/rcutorture/bin/functions.sh
index 6bcb8b5b2ff22..be3c5c73d7e79 100644
--- a/tools/testing/selftests/rcutorture/bin/functions.sh
+++ b/tools/testing/selftests/rcutorture/bin/functions.sh
@@ -172,7 +172,7 @@ identify_qemu_append () {
local console=ttyS0
case "$1" in
qemu-system-x86_64|qemu-system-i386)
- echo noapic selinux=0 initcall_debug debug
+ echo selinux=0 initcall_debug debug
;;
qemu-system-aarch64)
console=ttyAMA0
@@ -191,8 +191,19 @@ identify_qemu_append () {
# Output arguments for qemu arguments based on the TORTURE_QEMU_MAC
# and TORTURE_QEMU_INTERACTIVE environment variables.
identify_qemu_args () {
+ local KVM_CPU=""
+ case "$1" in
+ qemu-system-x86_64)
+ KVM_CPU=kvm64
+ ;;
+ qemu-system-i386)
+ KVM_CPU=kvm32
+ ;;
+ esac
case "$1" in
qemu-system-x86_64|qemu-system-i386)
+ echo -machine q35,accel=kvm
+ echo -cpu ${KVM_CPU},x2apic=on,tsc-deadline=on,hypervisor=on,tsc_adjust=on
;;
qemu-system-aarch64)
echo -machine virt,gic-version=host -cpu host
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/CFcommon b/tools/testing/selftests/rcutorture/configs/rcu/CFcommon
index d2d2a86139db1..322d5d40443cd 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/CFcommon
+++ b/tools/testing/selftests/rcutorture/configs/rcu/CFcommon
@@ -1,2 +1,6 @@
CONFIG_RCU_TORTURE_TEST=y
CONFIG_PRINTK_TIME=y
+CONFIG_HYPERVISOR_GUEST=y
+CONFIG_PARAVIRT=y
+CONFIG_PARAVIRT_SPINLOCKS=y
+CONFIG_KVM_GUEST=y
--
2.20.1
