On Wed, Apr 24, 2019 at 09:34:46AM +0200, Sebastian Andrzej Siewior wrote:
> 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>
Thank you, Sebastian! Queued for review and testing.
Thanx, Paul
> ---
> 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
>
