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| author | Gleb Natapov <gleb@redhat.com> | 2009-06-11 12:06:51 +0400 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2009-09-10 09:32:57 +0400 |
| commit | 33e4c68656a2e461b296ce714ec322978de85412 (patch) | |
| tree | 9fbadb2c192cc22dca24dc6dfac6804dba5e70e8 /arch/x86/kvm/lapic.c | |
| parent | 6edf14d8d0df144d6928799040f46fa37b5460ae (diff) | |
| download | linux-33e4c68656a2e461b296ce714ec322978de85412.tar.xz | |
KVM: Optimize searching for highest IRR
Most of the time IRR is empty, so instead of scanning the whole IRR on
each VM entry keep a variable that tells us if IRR is not empty. IRR
will have to be scanned twice on each IRQ delivery, but this is much
more rare than VM entry.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/x86/kvm/lapic.c')
| -rw-r--r-- | arch/x86/kvm/lapic.c | 24 |
1 files changed, 21 insertions, 3 deletions
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index b1694dc45729..3bde43c3789e 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -165,29 +165,46 @@ static int find_highest_vector(void *bitmap) static inline int apic_test_and_set_irr(int vec, struct kvm_lapic *apic) { + apic->irr_pending = true; return apic_test_and_set_vector(vec, apic->regs + APIC_IRR); } -static inline void apic_clear_irr(int vec, struct kvm_lapic *apic) +static inline int apic_search_irr(struct kvm_lapic *apic) { - apic_clear_vector(vec, apic->regs + APIC_IRR); + return find_highest_vector(apic->regs + APIC_IRR); } static inline int apic_find_highest_irr(struct kvm_lapic *apic) { int result; - result = find_highest_vector(apic->regs + APIC_IRR); + if (!apic->irr_pending) + return -1; + + result = apic_search_irr(apic); ASSERT(result == -1 || result >= 16); return result; } +static inline void apic_clear_irr(int vec, struct kvm_lapic *apic) +{ + apic->irr_pending = false; + apic_clear_vector(vec, apic->regs + APIC_IRR); + if (apic_search_irr(apic) != -1) + apic->irr_pending = true; +} + int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu) { struct kvm_lapic *apic = vcpu->arch.apic; int highest_irr; + /* This may race with setting of irr in __apic_accept_irq() and + * value returned may be wrong, but kvm_vcpu_kick() in __apic_accept_irq + * will cause vmexit immediately and the value will be recalculated + * on the next vmentry. + */ if (!apic) return 0; highest_irr = apic_find_highest_irr(apic); @@ -843,6 +860,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu) apic_set_reg(apic, APIC_ISR + 0x10 * i, 0); apic_set_reg(apic, APIC_TMR + 0x10 * i, 0); } + apic->irr_pending = false; update_divide_count(apic); atomic_set(&apic->lapic_timer.pending, 0); if (kvm_vcpu_is_bsp(vcpu)) |