KVM: X86: Lower the default timer frequency limit to 200us

[ Upstream commit 4c27625b7a67eb9006963ed2bcf8e53b259b43af ]

Anthoine reported:
 The period used by Windows change over time but it can be 1
 milliseconds or less. I saw the limit_periodic_timer_frequency
 print so 500 microseconds is sometimes reached.

As suggested by Paolo, lower the default timer frequency limit to a
smaller interval of 200 us (5000 Hz) to leave some headroom. This
is required due to Windows 10 changing the scheduler tick limit
from 1024 Hz to 2048 Hz.

Reported-by: Anthoine Bourgeois <anthoine.bourgeois@blade-group.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Anthoine Bourgeois <anthoine.bourgeois@blade-group.com>
Cc: Darren Kenny <darren.kenny@oracle.com>
Cc: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a43f9487f1366f09937fc23acb15a0084123e74b..f3a1f9f3fb296b773136f2dd96139a7d4e3f3771 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -112,7 +112,7 @@ module_param(ignore_msrs, bool, S_IRUGO | S_IWUSR);
 static bool __read_mostly report_ignored_msrs = true;
 module_param(report_ignored_msrs, bool, S_IRUGO | S_IWUSR);
 
-unsigned int min_timer_period_us = 500;
+unsigned int min_timer_period_us = 200;
 module_param(min_timer_period_us, uint, S_IRUGO | S_IWUSR);
 
 static bool __read_mostly kvmclock_periodic_sync = true;