2019-05-09 11:31:07

by Wanpeng Li

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

From: Wanpeng Li <[email protected]>

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 <[email protected]>
Cc: Radim Krčmář <[email protected]>
Cc: Sean Christopherson <[email protected]>
Cc: Liran Alon <[email protected]>
Signed-off-by: Wanpeng Li <[email protected]>
---
arch/x86/kvm/x86.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

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);
--
2.7.4

2019-05-13 19:53:57

by Sean Christopherson

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

On Thu, May 09, 2019 at 07:29:20PM +0800, Wanpeng Li wrote:
> From: Wanpeng Li <[email protected]>
>
> 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 <[email protected]>
> Cc: Radim Krčmář <[email protected]>
> Cc: Sean Christopherson <[email protected]>
> Cc: Liran Alon <[email protected]>
> Signed-off-by: Wanpeng Li <[email protected]>
> ---

Reviewed-by: Sean Christopherson <[email protected]>