From fd47b5af0ea0c984a1a2a79b7a503abf98e2f668 Mon Sep 17 00:00:00 2001
From: Marcelo Tosatti <mtosatti@redhat.com>
Date: Mon, 11 Mar 2013 23:10:24 -0300
Subject: [PATCH] --- yaml --- r: 372987 b: refs/heads/master c:
 03ba32cae66e3798d697e582633af2c7dd6907e5 h: refs/heads/master i:   372985:
 63d49daa6a4b99da4a4c7c28fc619ffee5d84d98   372983:
 96852f836d69456a71beaa5263885bb88e2354aa v: v3

---
 [refs]                   |  2 +-
 trunk/arch/x86/kvm/x86.c | 29 ++++++++++++++++++-----------
 2 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/[refs] b/[refs]
index 436d399c6795..4e220aa84922 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 0fa24ce3f57144e390a1566774c23434975a52a9
+refs/heads/master: 03ba32cae66e3798d697e582633af2c7dd6907e5
diff --git a/trunk/arch/x86/kvm/x86.c b/trunk/arch/x86/kvm/x86.c
index 35b491229c3a..b67985af1753 100644
--- a/trunk/arch/x86/kvm/x86.c
+++ b/trunk/arch/x86/kvm/x86.c
@@ -1079,6 +1079,10 @@ static void kvm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 this_tsc_khz)
 	u32 thresh_lo, thresh_hi;
 	int use_scaling = 0;
 
+	/* tsc_khz can be zero if TSC calibration fails */
+	if (this_tsc_khz == 0)
+		return;
+
 	/* Compute a scale to convert nanoseconds in TSC cycles */
 	kvm_get_time_scale(this_tsc_khz, NSEC_PER_SEC / 1000,
 			   &vcpu->arch.virtual_tsc_shift,
@@ -1156,20 +1160,23 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
 	ns = get_kernel_ns();
 	elapsed = ns - kvm->arch.last_tsc_nsec;
 
-	/* n.b - signed multiplication and division required */
-	usdiff = data - kvm->arch.last_tsc_write;
+	if (vcpu->arch.virtual_tsc_khz) {
+		/* n.b - signed multiplication and division required */
+		usdiff = data - kvm->arch.last_tsc_write;
 #ifdef CONFIG_X86_64
-	usdiff = (usdiff * 1000) / vcpu->arch.virtual_tsc_khz;
+		usdiff = (usdiff * 1000) / vcpu->arch.virtual_tsc_khz;
 #else
-	/* do_div() only does unsigned */
-	asm("idivl %2; xor %%edx, %%edx"
-	    : "=A"(usdiff)
-	    : "A"(usdiff * 1000), "rm"(vcpu->arch.virtual_tsc_khz));
+		/* do_div() only does unsigned */
+		asm("idivl %2; xor %%edx, %%edx"
+		: "=A"(usdiff)
+		: "A"(usdiff * 1000), "rm"(vcpu->arch.virtual_tsc_khz));
 #endif
-	do_div(elapsed, 1000);
-	usdiff -= elapsed;
-	if (usdiff < 0)
-		usdiff = -usdiff;
+		do_div(elapsed, 1000);
+		usdiff -= elapsed;
+		if (usdiff < 0)
+			usdiff = -usdiff;
+	} else
+		usdiff = USEC_PER_SEC; /* disable TSC match window below */
 
 	/*
 	 * Special case: TSC write with a small delta (1 second) of virtual