From: Steven Rostedt <rostedt@xxxxxxxxxxx>
Commit 92b5265d38f6a ("KVM: Depend on HIGH_RES_TIMERS") added a dependency
to high resolution timers with the comment:
KVM lapic timer and tsc deadline timer based on hrtimer,
setting a leftmost node to rb tree and then do hrtimer reprogram.
If hrtimer not configured as high resolution, hrtimer_enqueue_reprogram
do nothing and then make kvm lapic timer and tsc deadline timer fail.
That was back in 2012, where hrtimer_start_range_ns() would do the
reprogramming with hrtimer_enqueue_reprogram(). But as that was a nop with
high resolution timers disabled, this did not work. But a lot has changed
in the last 12 years.
For example, commit 49a2a07514a3a ("hrtimer: Kick lowres dynticks targets on
timer enqueue") modifies __hrtimer_start_range_ns() to work with low res
timers. There's been lots of other changes that make low res work.
I added this change to my main server that runs all my VMs (my mail
server, my web server, my ssh server) and disabled HIGH_RES_TIMERS and the
system has been running just fine for over a month.
ChromeOS has tested this before as well, and it hasn't seen any issues with
running KVM with high res timers disabled.
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
arch/x86/kvm/Kconfig | 1 -
1 file changed, 1 deletion(-)
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 472a1537b7a9..c65127e796a9 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -19,7 +19,6 @@ if VIRTUALIZATION
config KVM
tristate "Kernel-based Virtual Machine (KVM) support"
- depends on HIGH_RES_TIMERS
depends on X86_LOCAL_APIC
select KVM_COMMON
select KVM_GENERIC_MMU_NOTIFIER
--
2.43.0
