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Subject[PATCH v2 1/4] KVM: LAPIC: Fix lapic timer mode transition
Date
From: Wanpeng Li <wanpeng.li@hotmail.com>

SDM 10.5.4.1 TSC-Deadline Mode mentioned that "Transitioning between TSC-Deadline
mode and other timer modes also disarms the timer". So the APIC Timer Initial Count
Register for one-shot/periodic mode should be reset. This patch do it.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
arch/x86/include/asm/apicdef.h | 1 +
arch/x86/kvm/lapic.c | 3 +++
2 files changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/apicdef.h b/arch/x86/include/asm/apicdef.h
index c46bb99..d8ef1b4 100644
--- a/arch/x86/include/asm/apicdef.h
+++ b/arch/x86/include/asm/apicdef.h
@@ -100,6 +100,7 @@
#define APIC_TIMER_BASE_CLKIN 0x0
#define APIC_TIMER_BASE_TMBASE 0x1
#define APIC_TIMER_BASE_DIV 0x2
+#define APIC_LVT_TIMER_MASK (3 << 17)
#define APIC_LVT_TIMER_ONESHOT (0 << 17)
#define APIC_LVT_TIMER_PERIODIC (1 << 17)
#define APIC_LVT_TIMER_TSCDEADLINE (2 << 17)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 69c5612..a739cbb 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1722,6 +1722,9 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
break;

case APIC_LVTT:
+ if (apic_lvtt_tscdeadline(apic) != ((val &
+ APIC_LVT_TIMER_MASK) == APIC_LVT_TIMER_TSCDEADLINE))
+ kvm_lapic_set_reg(apic, APIC_TMICT, 0);
if (!kvm_apic_sw_enabled(apic))
val |= APIC_LVT_MASKED;
val &= (apic_lvt_mask[0] | apic->lapic_timer.timer_mode_mask);
--
2.7.4
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