linux-kernel - [PATCH 1/3] KVM: x86: handle 0 write to TSC

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Message-Id: <20171006172555.30087-2-rkrcmar@redhat.com>
Date:   Fri,  6 Oct 2017 19:25:53 +0200
From:   Radim Krčmář <rkrcmar@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Wanpeng Li <kernellwp@...il.com>
Subject: [PATCH 1/3] KVM: x86: handle 0 write to TSC_DEADLINE MSR

0 should disable the timer, but start_hv_timer will recognize it as an
expired timer instead.

Signed-off-by: Radim Krčmář <rkrcmar@...hat.com>
---
 arch/x86/kvm/lapic.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 2c9e88a82738..39c1ae11ce1d 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1549,6 +1549,9 @@ static bool start_hv_timer(struct kvm_lapic *apic)
 	if (!apic_lvtt_period(apic) && atomic_read(&ktimer->pending))
 		return false;
 
+	if (!ktimer->tscdeadline)
+		return false;
+
 	r = kvm_x86_ops->set_hv_timer(apic->vcpu, ktimer->tscdeadline);
 	if (r < 0)
 		return false;
-- 
2.14.2