diff mbox series

[2/3] KVM: LAPIC: Fix lapic_timer_advance_ns parameter overflow

Message ID 1557401361-3828-3-git-send-email-wanpengli@tencent.com (mailing list archive)
State New, archived
Headers show
Series KVM: LAPIC: Optimize timer latency further | expand

Commit Message

Wanpeng Li May 9, 2019, 11:29 a.m. UTC 
From: Wanpeng Li <wanpengli@tencent.com>

After commit c3941d9e0 (KVM: lapic: Allow user to disable adaptive tuning of 
timer advancement), '-1' enables adaptive tuning starting from default 
advancment of 1000ns. However, we should expose an int instead of an overflow 
uint module parameter.

Before patch:

/sys/module/kvm/parameters/lapic_timer_advance_ns:4294967295

After patch:

/sys/module/kvm/parameters/lapic_timer_advance_ns:-1

Fixes: c3941d9e0 (KVM: lapic: Allow user to disable adaptive tuning of timer advancement)
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
 arch/x86/kvm/x86.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Sean Christopherson May 13, 2019, 7:14 p.m. UTC | #1 
On Thu, May 09, 2019 at 07:29:20PM +0800, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
> 
> After commit c3941d9e0 (KVM: lapic: Allow user to disable adaptive tuning of 
> timer advancement), '-1' enables adaptive tuning starting from default 
> advancment of 1000ns. However, we should expose an int instead of an overflow 
> uint module parameter.
> 
> Before patch:
> 
> /sys/module/kvm/parameters/lapic_timer_advance_ns:4294967295
> 
> After patch:
> 
> /sys/module/kvm/parameters/lapic_timer_advance_ns:-1
> 
> Fixes: c3941d9e0 (KVM: lapic: Allow user to disable adaptive tuning of timer advancement)
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Cc: Sean Christopherson <sean.j.christopherson@intel.com>
> Cc: Liran Alon <liran.alon@oracle.com>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---

Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
diff mbox series

Patch

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d75bb97..1d89cb9 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -143,7 +143,7 @@  module_param(tsc_tolerance_ppm, uint, S_IRUGO | S_IWUSR);
  * tuning, i.e. allows priveleged userspace to set an exact advancement time.
  */
 static int __read_mostly lapic_timer_advance_ns = -1;
-module_param(lapic_timer_advance_ns, uint, S_IRUGO | S_IWUSR);
+module_param(lapic_timer_advance_ns, int, S_IRUGO | S_IWUSR);
 
 static bool __read_mostly vector_hashing = true;
 module_param(vector_hashing, bool, S_IRUGO);