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;

[jan: use do_div()]
[avi: fix for !irqchip_in_kernel()]
[marcelo: another fix for !irqchip_in_kernel()]

Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

5 files changed, 140 insertions, 30 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index ab62711ccb78..b4973f4dab98 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -674,6 +674,8 @@ u8 kvm_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn);
 
 extern bool tdp_enabled;
 
+u64 vcpu_tsc_khz(struct kvm_vcpu *vcpu);
+
 /* control of guest tsc rate supported? */
 extern bool kvm_has_tsc_control;
 /* minimum supported tsc_khz for guests */
diff --git a/arch/x86/kvm/kvm_timer.h b/arch/x86/kvm/kvm_timer.h
index 64bc6ea78d90..497dbaa366d4 100644
--- a/arch/x86/kvm/kvm_timer.h
+++ b/arch/x86/kvm/kvm_timer.h
@@ -2,6 +2,8 @@
 struct kvm_timer {
         struct hrtimer timer;
         s64 period;                             /* unit: ns */
+        u32 timer_mode_mask;
+        u64 tscdeadline;
         atomic_t pending;                       /* accumulated triggered timers */
         bool reinject;
         struct kvm_timer_ops *t_ops;
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 2fb20caae5d8..54abb40199d6 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -138,9 +138,23 @@ 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)
@@ -169,7 +183,7 @@ 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 */
@@ -572,6 +586,9 @@ 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;
 
@@ -666,37 +683,40 @@ 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)) {
-                s64 min_period = min_timer_period_us * 1000LL;
-
-                if (apic->lapic_timer.period < min_period) {
-                        pr_info_ratelimited(
-                                "kvm: vcpu %i: requested %lld ns "
-                                "lapic timer period limited to %lld ns\n",
-                                apic->vcpu->vcpu_id, apic->lapic_timer.period,
-                                min_period);
-                        apic->lapic_timer.period = min_period;
+        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)) {
+                        s64 min_period = min_timer_period_us * 1000LL;
+
+                        if (apic->lapic_timer.period < min_period) {
+                                pr_info_ratelimited(
+                                    "kvm: vcpu %i: requested %lld ns "
+                                    "lapic timer period limited to %lld ns\n",
+                                    apic->vcpu->vcpu_id,
+                                    apic->lapic_timer.period, min_period);
+                                apic->lapic_timer.period = min_period;
+                        }
                 }
-        }
 
-        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__,
@@ -705,6 +725,30 @@ 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, tscdeadline = apic->lapic_timer.tscdeadline;
+                u64 ns = 0;
+                struct kvm_vcpu *vcpu = apic->vcpu;
+                unsigned long this_tsc_khz = vcpu_tsc_khz(vcpu);
+                unsigned long flags;
+
+                if (unlikely(!tscdeadline || !this_tsc_khz))
+                        return;
+
+                local_irq_save(flags);
+
+                now = apic->lapic_timer.timer.base->get_time();
+                guest_tsc = kvm_x86_ops->read_l1_tsc(vcpu);
+                if (likely(tscdeadline > guest_tsc)) {
+                        ns = (tscdeadline - guest_tsc) * 1000000ULL;
+                        do_div(ns, this_tsc_khz);
+                }
+                hrtimer_start(&apic->lapic_timer.timer,
+                        ktime_add_ns(now, ns), HRTIMER_MODE_ABS);
+
+                local_irq_restore(flags);
+        }
 }
 
 static void apic_manage_nmi_watchdog(struct kvm_lapic *apic, u32 lvt0_val)
@@ -792,7 +836,6 @@ static int apic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
 
         case APIC_LVT0:
                 apic_manage_nmi_watchdog(apic, val);
-        case APIC_LVTT:
         case APIC_LVTTHMR:
         case APIC_LVTPC:
         case APIC_LVT1:
@@ -806,7 +849,22 @@ static int apic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
 
                 break;
 
+        case APIC_LVTT:
+                if ((apic_get_reg(apic, APIC_LVTT) &
+                    apic->lapic_timer.timer_mode_mask) !=
+                   (val & apic->lapic_timer.timer_mode_mask))
+                        hrtimer_cancel(&apic->lapic_timer.timer);
+
+                if (!apic_sw_enabled(apic))
+                        val |= APIC_LVT_MASKED;
+                val &= (apic_lvt_mask[0] | apic->lapic_timer.timer_mode_mask);
+                apic_set_reg(apic, APIC_LVTT, val);
+                break;
+
         case APIC_TMICT:
+                if (apic_lvtt_tscdeadline(apic))
+                        break;
+
                 hrtimer_cancel(&apic->lapic_timer.timer);
                 apic_set_reg(apic, APIC_TMICT, val);
                 start_apic_timer(apic);
@@ -902,6 +960,32 @@ void kvm_free_lapic(struct kvm_vcpu *vcpu)
  *----------------------------------------------------------------------
  */
 
+u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu)
+{
+        struct kvm_lapic *apic = vcpu->arch.apic;
+        if (!apic)
+                return 0;
+
+        if (apic_lvtt_oneshot(apic) || apic_lvtt_period(apic))
+                return 0;
+
+        return apic->lapic_timer.tscdeadline;
+}
+
+void kvm_set_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu, u64 data)
+{
+        struct kvm_lapic *apic = vcpu->arch.apic;
+        if (!apic)
+                return;
+
+        if (apic_lvtt_oneshot(apic) || apic_lvtt_period(apic))
+                return;
+
+        hrtimer_cancel(&apic->lapic_timer.timer);
+        apic->lapic_timer.tscdeadline = data;
+        start_apic_timer(apic);
+}
+
 void kvm_lapic_set_tpr(struct kvm_vcpu *vcpu, unsigned long cr8)
 {
         struct kvm_lapic *apic = vcpu->arch.apic;
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 82872432d475..138e8cc6fea6 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -42,6 +42,9 @@ int kvm_lapic_enabled(struct kvm_vcpu *vcpu);
 bool kvm_apic_present(struct kvm_vcpu *vcpu);
 int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu);
 
+u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu);
+void kvm_set_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu, u64 data);
+
 void kvm_lapic_set_vapic_addr(struct kvm_vcpu *vcpu, gpa_t vapic_addr);
 void kvm_lapic_sync_from_vapic(struct kvm_vcpu *vcpu);
 void kvm_lapic_sync_to_vapic(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d51e40733fcb..cf269096eadf 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -600,6 +600,8 @@ static bool guest_cpuid_has_fsgsbase(struct kvm_vcpu *vcpu)
 static void update_cpuid(struct kvm_vcpu *vcpu)
 {
         struct kvm_cpuid_entry2 *best;
+        struct kvm_lapic *apic = vcpu->arch.apic;
+        u32 timer_mode_mask;
 
         best = kvm_find_cpuid_entry(vcpu, 1, 0);
         if (!best)
@@ -611,6 +613,16 @@ static void update_cpuid(struct kvm_vcpu *vcpu)
                 if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE))
                         best->ecx |= bit(X86_FEATURE_OSXSAVE);
         }
+
+        if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
+                best->function == 0x1) {
+                best->ecx |= bit(X86_FEATURE_TSC_DEADLINE_TIMER);
+                timer_mode_mask = 3 << 17;
+        } else
+                timer_mode_mask = 1 << 17;
+
+        if (apic)
+                apic->lapic_timer.timer_mode_mask = timer_mode_mask;
 }
 
 int kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
@@ -826,6 +838,7 @@ static u32 msrs_to_save[] = {
 static unsigned num_msrs_to_save;
 
 static u32 emulated_msrs[] = {
+        MSR_IA32_TSCDEADLINE,
         MSR_IA32_MISC_ENABLE,
         MSR_IA32_MCG_STATUS,
         MSR_IA32_MCG_CTL,
@@ -1001,7 +1014,7 @@ static inline int kvm_tsc_changes_freq(void)
         return ret;
 }
 
-static u64 vcpu_tsc_khz(struct kvm_vcpu *vcpu)
+u64 vcpu_tsc_khz(struct kvm_vcpu *vcpu)
 {
         if (vcpu->arch.virtual_tsc_khz)
                 return vcpu->arch.virtual_tsc_khz;
@@ -1565,6 +1578,9 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
                 break;
         case APIC_BASE_MSR ... APIC_BASE_MSR + 0x3ff:
                 return kvm_x2apic_msr_write(vcpu, msr, data);
+        case MSR_IA32_TSCDEADLINE:
+                kvm_set_lapic_tscdeadline_msr(vcpu, data);
+                break;
         case MSR_IA32_MISC_ENABLE:
                 vcpu->arch.ia32_misc_enable_msr = data;
                 break;
@@ -1894,6 +1910,9 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
         case APIC_BASE_MSR ... APIC_BASE_MSR + 0x3ff:
                 return kvm_x2apic_msr_read(vcpu, msr, pdata);
                 break;
+        case MSR_IA32_TSCDEADLINE:
+                data = kvm_get_lapic_tscdeadline_msr(vcpu);
+                break;
         case MSR_IA32_MISC_ENABLE:
                 data = vcpu->arch.ia32_misc_enable_msr;
                 break;