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Subject[patch 74/88] KVM: x86: fix LAPIC pending count calculation
2.6.28-stable review patch.  If anyone has any objections, please let us know.

------------------

(cherry picked from b682b814e3cc340f905c14dff87ce8bdba7c5eba)

Simplify LAPIC TMCCT calculation by using hrtimer provided
function to query remaining time until expiration.

Fixes host hang with nested ESX.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
arch/x86/kvm/irq.c | 7 -----
arch/x86/kvm/irq.h | 1
arch/x86/kvm/lapic.c | 66 +++++++++++----------------------------------------
arch/x86/kvm/lapic.h | 2 -
arch/x86/kvm/svm.c | 1
arch/x86/kvm/vmx.c | 4 ---
6 files changed, 16 insertions(+), 65 deletions(-)
--- a/arch/x86/kvm/irq.c
+++ b/arch/x86/kvm/irq.c
@@ -87,13 +87,6 @@ void kvm_inject_pending_timer_irqs(struc
}
EXPORT_SYMBOL_GPL(kvm_inject_pending_timer_irqs);

-void kvm_timer_intr_post(struct kvm_vcpu *vcpu, int vec)
-{
- kvm_apic_timer_intr_post(vcpu, vec);
- /* TODO: PIT, RTC etc. */
-}
-EXPORT_SYMBOL_GPL(kvm_timer_intr_post);
-
void __kvm_migrate_timers(struct kvm_vcpu *vcpu)
{
__kvm_migrate_apic_timer(vcpu);
--- a/arch/x86/kvm/irq.h
+++ b/arch/x86/kvm/irq.h
@@ -84,7 +84,6 @@ static inline int irqchip_in_kernel(stru

void kvm_pic_reset(struct kvm_kpic_state *s);

-void kvm_timer_intr_post(struct kvm_vcpu *vcpu, int vec);
void kvm_inject_pending_timer_irqs(struct kvm_vcpu *vcpu);
void kvm_inject_apic_timer_irqs(struct kvm_vcpu *vcpu);
void __kvm_migrate_apic_timer(struct kvm_vcpu *vcpu);
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -35,6 +35,12 @@
#include "kvm_cache_regs.h"
#include "irq.h"

+#ifndef CONFIG_X86_64
+#define mod_64(x, y) ((x) - (y) * div64_u64(x, y))
+#else
+#define mod_64(x, y) ((x) % (y))
+#endif
+
#define PRId64 "d"
#define PRIx64 "llx"
#define PRIu64 "u"
@@ -497,52 +503,22 @@ static void apic_send_ipi(struct kvm_lap

static u32 apic_get_tmcct(struct kvm_lapic *apic)
{
- u64 counter_passed;
- ktime_t passed, now;
+ ktime_t remaining;
+ s64 ns;
u32 tmcct;

ASSERT(apic != NULL);

- now = apic->timer.dev.base->get_time();
- tmcct = apic_get_reg(apic, APIC_TMICT);
-
/* if initial count is 0, current count should also be 0 */
- if (tmcct == 0)
+ if (apic_get_reg(apic, APIC_TMICT) == 0)
return 0;

- if (unlikely(ktime_to_ns(now) <=
- ktime_to_ns(apic->timer.last_update))) {
- /* Wrap around */
- passed = ktime_add(( {
- (ktime_t) {
- .tv64 = KTIME_MAX -
- (apic->timer.last_update).tv64}; }
- ), now);
- apic_debug("time elapsed\n");
- } else
- passed = ktime_sub(now, apic->timer.last_update);
-
- counter_passed = div64_u64(ktime_to_ns(passed),
- (APIC_BUS_CYCLE_NS * apic->timer.divide_count));
-
- if (counter_passed > tmcct) {
- if (unlikely(!apic_lvtt_period(apic))) {
- /* one-shot timers stick at 0 until reset */
- tmcct = 0;
- } else {
- /*
- * periodic timers reset to APIC_TMICT when they
- * hit 0. The while loop simulates this happening N
- * times. (counter_passed %= tmcct) would also work,
- * but might be slower or not work on 32-bit??
- */
- while (counter_passed > tmcct)
- counter_passed -= tmcct;
- tmcct -= counter_passed;
- }
- } else {
- tmcct -= counter_passed;
- }
+ remaining = hrtimer_expires_remaining(&apic->timer.dev);
+ if (ktime_to_ns(remaining) < 0)
+ remaining = ktime_set(0, 0);
+
+ ns = mod_64(ktime_to_ns(remaining), apic->timer.period);
+ tmcct = div64_u64(ns, (APIC_BUS_CYCLE_NS * apic->timer.divide_count));

return tmcct;
}
@@ -639,8 +615,6 @@ static void start_apic_timer(struct kvm_
{
ktime_t now = apic->timer.dev.base->get_time();

- apic->timer.last_update = now;
-
apic->timer.period = apic_get_reg(apic, APIC_TMICT) *
APIC_BUS_CYCLE_NS * apic->timer.divide_count;
atomic_set(&apic->timer.pending, 0);
@@ -1068,16 +1042,6 @@ void kvm_inject_apic_timer_irqs(struct k
}
}

-void kvm_apic_timer_intr_post(struct kvm_vcpu *vcpu, int vec)
-{
- struct kvm_lapic *apic = vcpu->arch.apic;
-
- if (apic && apic_lvt_vector(apic, APIC_LVTT) == vec)
- apic->timer.last_update = ktime_add_ns(
- apic->timer.last_update,
- apic->timer.period);
-}
-
int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu)
{
int vector = kvm_apic_has_interrupt(vcpu);
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -12,7 +12,6 @@ struct kvm_lapic {
atomic_t pending;
s64 period; /* unit: ns */
u32 divide_count;
- ktime_t last_update;
struct hrtimer dev;
} timer;
struct kvm_vcpu *vcpu;
@@ -42,7 +41,6 @@ void kvm_set_apic_base(struct kvm_vcpu *
void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu);
int kvm_lapic_enabled(struct kvm_vcpu *vcpu);
int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu);
-void kvm_apic_timer_intr_post(struct kvm_vcpu *vcpu, int vec);

void kvm_lapic_set_vapic_addr(struct kvm_vcpu *vcpu, gpa_t vapic_addr);
void kvm_lapic_sync_from_vapic(struct kvm_vcpu *vcpu);
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1612,7 +1612,6 @@ static void svm_intr_assist(struct kvm_v
/* Okay, we can deliver the interrupt: grab it and update PIC state. */
intr_vector = kvm_cpu_get_interrupt(vcpu);
svm_inject_irq(svm, intr_vector);
- kvm_timer_intr_post(vcpu, intr_vector);
out:
update_cr8_intercept(vcpu);
}
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3171,10 +3171,8 @@ static void vmx_intr_assist(struct kvm_v
else
enable_irq_window(vcpu);
}
- if (vcpu->arch.interrupt.pending) {
+ if (vcpu->arch.interrupt.pending)
vmx_inject_irq(vcpu, vcpu->arch.interrupt.nr);
- kvm_timer_intr_post(vcpu, vcpu->arch.interrupt.nr);
- }
}

/*



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