linux-kernel - [PATCH 2/3] KVM: LAPIC: Fix lapic_timer_advance

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Message-Id: <1557401361-3828-3-git-send-email-wanpengli@tencent.com>
Date:   Thu,  9 May 2019 19:29:20 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Liran Alon <liran.alon@...cle.com>
Subject: [PATCH 2/3] KVM: LAPIC: Fix lapic_timer_advance_ns parameter overflow

From: Wanpeng Li <wanpengli@...cent.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@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Cc: Sean Christopherson <sean.j.christopherson@...el.com>
Cc: Liran Alon <liran.alon@...cle.com>
Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
---
 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