2017-09-28 18:04-0700, Wanpeng Li: > From: Wanpeng Li <wanpeng.li@xxxxxxxxxxx> > > 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. At the beginning of the secion is also: A write to the LVT Timer Register that changes the timer mode disarms the local APIC timer. The supported timer modes are given in Table 10-2. The three modes of the local APIC timer are mutually exclusive. So we should also disarm when switching between one-shot and periodic. apic_update_lvtt() already has logic to determine whether the timer mode has changed and is the perfect place to clear APIC_TMICT. Thanks. > Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> > Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx> > Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx> > --- > 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 >
