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| author | Marcelo Tosatti <mtosatti@redhat.com> | 2008-09-25 03:28:34 +0400 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2008-10-15 16:25:28 +0400 |
| commit | e48258009d941891fca35348986b8d280caf31cd (patch) | |
| tree | 73d1fb56a9fc22c1e55160bb04e772bd6b2244fb /arch/x86/kvm/irq.h | |
| parent | 582801a95d2f2ceab841779e1dec0e11dfec44c0 (diff) | |
| download | linux-e48258009d941891fca35348986b8d280caf31cd.tar.xz | |
KVM: PIC: enhance IPI avoidance
The PIC code makes little effort to avoid kvm_vcpu_kick(), resulting in
unnecessary guest exits in some conditions.
For example, if the timer interrupt is routed through the IOAPIC, IRR
for IRQ 0 will get set but not cleared, since the APIC is handling the
acks.
This means that everytime an interrupt < 16 is triggered, the priority
logic will find IRQ0 pending and send an IPI to vcpu0 (in case IRQ0 is
not masked, which is Linux's case).
Introduce a new variable isr_ack to represent the IRQ's for which the
guest has been signalled / cleared the ISR. Use it to avoid more than
one IPI per trigger-ack cycle, in addition to the avoidance when ISR is
set in get_priority().
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/x86/kvm/irq.h')
| -rw-r--r-- | arch/x86/kvm/irq.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h index 479a3d2d5614..4748532fd1da 100644 --- a/arch/x86/kvm/irq.h +++ b/arch/x86/kvm/irq.h @@ -42,6 +42,7 @@ struct kvm_kpic_state { u8 irr; /* interrupt request register */ u8 imr; /* interrupt mask register */ u8 isr; /* interrupt service register */ + u8 isr_ack; /* interrupt ack detection */ u8 priority_add; /* highest irq priority */ u8 irq_base; u8 read_reg_select; @@ -70,6 +71,7 @@ struct kvm_pic *kvm_create_pic(struct kvm *kvm); void kvm_pic_set_irq(void *opaque, int irq, int level); int kvm_pic_read_irq(struct kvm *kvm); void kvm_pic_update_irq(struct kvm_pic *s); +void kvm_pic_clear_isr_ack(struct kvm *kvm); static inline struct kvm_pic *pic_irqchip(struct kvm *kvm) { |