On Tue, Sep 13, 2011 at 10:36:51PM +0800, Liu, Jinsong wrote:
> >From 7b12021e1d1b79797b49e41cc0a7be05a6180d9a Mon Sep 17 00:00:00 2001
> From: Liu, Jinsong <jinsong.liu@xxxxxxxxx>
> Date: Tue, 13 Sep 2011 21:52:54 +0800
> Subject: [PATCH] KVM: emulate lapic tsc deadline timer for guest
>
> This patch emulate lapic tsc deadline timer for guest:
> Enumerate tsc deadline timer capability by CPUID;
> Enable tsc deadline timer mode by lapic MMIO;
> Start tsc deadline timer by WRMSR;
>
> Signed-off-by: Liu, Jinsong <jinsong.liu@xxxxxxxxx>
> ---
> arch/x86/include/asm/apicdef.h | 2 +
> arch/x86/include/asm/cpufeature.h | 3 +
> arch/x86/include/asm/kvm_host.h | 2 +
> arch/x86/include/asm/msr-index.h | 2 +
> arch/x86/kvm/kvm_timer.h | 2 +
> arch/x86/kvm/lapic.c | 122 ++++++++++++++++++++++++++++++-------
> arch/x86/kvm/lapic.h | 3 +
> arch/x86/kvm/x86.c | 20 ++++++-
> 8 files changed, 132 insertions(+), 24 deletions(-)
>
> diff --git a/arch/x86/include/asm/apicdef.h b/arch/x86/include/asm/apicdef.h
> index 34595d5..3925d80 100644
> --- a/arch/x86/include/asm/apicdef.h
> +++ b/arch/x86/include/asm/apicdef.h
> @@ -100,7 +100,9 @@
> #define APIC_TIMER_BASE_CLKIN 0x0
> #define APIC_TIMER_BASE_TMBASE 0x1
> #define APIC_TIMER_BASE_DIV 0x2
> +#define APIC_LVT_TIMER_ONESHOT (0 << 17)
> #define APIC_LVT_TIMER_PERIODIC (1 << 17)
> +#define APIC_LVT_TIMER_TSCDEADLINE (2 << 17)
> #define APIC_LVT_MASKED (1 << 16)
> #define APIC_LVT_LEVEL_TRIGGER (1 << 15)
> #define APIC_LVT_REMOTE_IRR (1 << 14)
Please have a separate, introductory patch for definitions that are not
KVM specific.
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -671,6 +671,8 @@ u8 kvm_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn);
>
> extern bool tdp_enabled;
>
> +extern u64 vcpu_tsc_khz(struct kvm_vcpu *vcpu);
> +
No need for extern.
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 2b2255b..925d4b9 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -135,9 +135,23 @@ static inline int apic_lvt_vector(struct kvm_lapic *apic, int lvt_type)
> return apic_get_reg(apic, lvt_type) & APIC_VECTOR_MASK;
> }
>
> +static inline int apic_lvtt_oneshot(struct kvm_lapic *apic)
> +{
> + return ((apic_get_reg(apic, APIC_LVTT) &
> + apic->lapic_timer.timer_mode_mask) == APIC_LVT_TIMER_ONESHOT);
> +}
> +
> static inline int apic_lvtt_period(struct kvm_lapic *apic)
> {
> - return apic_get_reg(apic, APIC_LVTT) & APIC_LVT_TIMER_PERIODIC;
> + return ((apic_get_reg(apic, APIC_LVTT) &
> + apic->lapic_timer.timer_mode_mask) == APIC_LVT_TIMER_PERIODIC);
> +}
> +
> +static inline int apic_lvtt_tscdeadline(struct kvm_lapic *apic)
> +{
> + return ((apic_get_reg(apic, APIC_LVTT) &
> + apic->lapic_timer.timer_mode_mask) ==
> + APIC_LVT_TIMER_TSCDEADLINE);
> }
>
> static inline int apic_lvt_nmi_mode(u32 lvt_val)
> @@ -166,7 +180,7 @@ static inline int apic_x2apic_mode(struct kvm_lapic *apic)
> }
>
> static unsigned int apic_lvt_mask[APIC_LVT_NUM] = {
> - LVT_MASK | APIC_LVT_TIMER_PERIODIC, /* LVTT */
> + LVT_MASK , /* part LVTT mask, timer mode mask added at runtime */
> LVT_MASK | APIC_MODE_MASK, /* LVTTHMR */
> LVT_MASK | APIC_MODE_MASK, /* LVTPC */
> LINT_MASK, LINT_MASK, /* LVT0-1 */
> @@ -570,6 +584,9 @@ static u32 __apic_read(struct kvm_lapic *apic, unsigned int offset)
> break;
>
> case APIC_TMCCT: /* Timer CCR */
> + if (apic_lvtt_tscdeadline(apic))
> + return 0;
> +
> val = apic_get_tmcct(apic);
> break;
>
> @@ -664,29 +681,32 @@ static void update_divide_count(struct kvm_lapic *apic)
>
> static void start_apic_timer(struct kvm_lapic *apic)
> {
> - ktime_t now = apic->lapic_timer.timer.base->get_time();
> -
> - apic->lapic_timer.period = (u64)apic_get_reg(apic, APIC_TMICT) *
> - APIC_BUS_CYCLE_NS * apic->divide_count;
> + ktime_t now;
> atomic_set(&apic->lapic_timer.pending, 0);
>
> - if (!apic->lapic_timer.period)
> - return;
> - /*
> - * Do not allow the guest to program periodic timers with small
> - * interval, since the hrtimers are not throttled by the host
> - * scheduler.
> - */
> - if (apic_lvtt_period(apic)) {
> - if (apic->lapic_timer.period < NSEC_PER_MSEC/2)
> - apic->lapic_timer.period = NSEC_PER_MSEC/2;
> - }
> + if (apic_lvtt_period(apic) || apic_lvtt_oneshot(apic)) {
> + /* lapic timer in oneshot or peroidic mode */
> + now = apic->lapic_timer.timer.base->get_time();
> + apic->lapic_timer.period = (u64)apic_get_reg(apic, APIC_TMICT)
> + * APIC_BUS_CYCLE_NS * apic->divide_count;
> +
> + if (!apic->lapic_timer.period)
> + return;
> + /*
> + * Do not allow the guest to program periodic timers with small
> + * interval, since the hrtimers are not throttled by the host
> + * scheduler.
> + */
> + if (apic_lvtt_period(apic)) {
> + if (apic->lapic_timer.period < NSEC_PER_MSEC/2)
> + apic->lapic_timer.period = NSEC_PER_MSEC/2;
> + }
>
> - hrtimer_start(&apic->lapic_timer.timer,
> - ktime_add_ns(now, apic->lapic_timer.period),
> - HRTIMER_MODE_ABS);
> + hrtimer_start(&apic->lapic_timer.timer,
> + ktime_add_ns(now, apic->lapic_timer.period),
> + HRTIMER_MODE_ABS);
>
> - apic_debug("%s: bus cycle is %" PRId64 "ns, now 0x%016"
> + apic_debug("%s: bus cycle is %" PRId64 "ns, now 0x%016"
> PRIx64 ", "
> "timer initial count 0x%x, period %lldns, "
> "expire @ 0x%016" PRIx64 ".\n", __func__,
> @@ -695,6 +715,28 @@ static void start_apic_timer(struct kvm_lapic *apic)
> apic->lapic_timer.period,
> ktime_to_ns(ktime_add_ns(now,
> apic->lapic_timer.period)));
> + } else if (apic_lvtt_tscdeadline(apic)) {
> + /* lapic timer in tsc deadline mode */
> + u64 guest_tsc, guest_tsc_delta, ns = 0;
> + struct kvm_vcpu *vcpu = apic->vcpu;
> + unsigned long this_tsc_khz = vcpu_tsc_khz(vcpu);
> + unsigned long flags;
> +
> + if (unlikely(!apic->lapic_timer.tscdeadline || !this_tsc_khz))
> + return;
> +
> + local_irq_save(flags);
> +
> + now = apic->lapic_timer.timer.base->get_time();
> + kvm_get_msr(vcpu, MSR_IA32_TSC, &guest_tsc);
Use kvm_x86_ops->read_l1_tsc(vcpu) instead of direct MSR read
(to avoid reading L2 guest TSC in case of nested virt).
> + guest_tsc_delta = apic->lapic_timer.tscdeadline - guest_tsc;
if (guest_tsc <= tscdeadline), the timer should start immediately.
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 6cb353c..a73c059 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -610,6 +610,16 @@ static void update_cpuid(struct kvm_vcpu *vcpu)
> if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE))
> best->ecx |= bit(X86_FEATURE_OSXSAVE);
> }
> +
> + /*
> + * When cpu has tsc deadline timer capacibility, use bit 17/18
> + * as timer mode mask. Otherwise only use bit 17.
> + */
> + if (cpu_has_tsc_deadline_timer && best->function == 0x1) {
> + best->ecx |= bit(X86_FEATURE_TSC_DEADLINE_TIMER);
> + vcpu->arch.apic->lapic_timer.timer_mode_mask = (3 << 17);
> + } else
> + vcpu->arch.apic->lapic_timer.timer_mode_mask = (1 << 17);
> }
The deadline timer is entirely emulated, whether the host CPU supports
it or not is irrelevant.
Why was this changed from previous submissions?
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