From 0247586f76f5e37ca63285fee24e527e7b80a20d Mon Sep 17 00:00:00 2001
From: Jan Kiszka <jan.kiszka@siemens.com>
Date: Mon, 12 Sep 2011 14:10:22 +0200
Subject: [PATCH] --- yaml --- r: 271523 b: refs/heads/master c:
 9bc5791d4aa78b72abd76f506c0a391a54abc4d1 h: refs/heads/master i:   271521:
 b4080b22504b3db722d2e9336b4f4b4bc07c02f7   271519:
 b2538392cbe65abc73c24c6b5c9270a84ec7f36a v: v3

---
 [refs]                     |  2 +-
 trunk/arch/x86/kvm/lapic.c | 15 +++++++++++++--
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/[refs] b/[refs]
index ee7121a68ab2..aa7ac0fe85ee 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: bd80158aff71a80292f96d9baea1a65bc0ce87b3
+refs/heads/master: 9bc5791d4aa78b72abd76f506c0a391a54abc4d1
diff --git a/trunk/arch/x86/kvm/lapic.c b/trunk/arch/x86/kvm/lapic.c
index 4b53b811d1c1..2fb20caae5d8 100644
--- a/trunk/arch/x86/kvm/lapic.c
+++ b/trunk/arch/x86/kvm/lapic.c
@@ -68,6 +68,9 @@
 #define VEC_POS(v) ((v) & (32 - 1))
 #define REG_POS(v) (((v) >> 5) << 4)
 
+static unsigned int min_timer_period_us = 500;
+module_param(min_timer_period_us, uint, S_IRUGO | S_IWUSR);
+
 static inline u32 apic_get_reg(struct kvm_lapic *apic, int reg_off)
 {
 	return *((u32 *) (apic->regs + reg_off));
@@ -677,8 +680,16 @@ static void start_apic_timer(struct kvm_lapic *apic)
 	 * scheduler.
 	 */
 	if (apic_lvtt_period(apic)) {
-		if (apic->lapic_timer.period < NSEC_PER_MSEC/2)
-			apic->lapic_timer.period = NSEC_PER_MSEC/2;
+		s64 min_period = min_timer_period_us * 1000LL;
+
+		if (apic->lapic_timer.period < min_period) {
+			pr_info_ratelimited(
+				"kvm: vcpu %i: requested %lld ns "
+				"lapic timer period limited to %lld ns\n",
+				apic->vcpu->vcpu_id, apic->lapic_timer.period,
+				min_period);
+			apic->lapic_timer.period = min_period;
+		}
 	}
 
 	hrtimer_start(&apic->lapic_timer.timer,