KVM: host side for eoi optimization
Implementation of PV EOI using shared memory.
This reduces the number of exits an interrupt
causes as much as by half.
The idea is simple: there's a bit, per APIC, in guest memory,
that tells the guest that it does not need EOI.
We set it before injecting an interrupt and clear
before injecting a nested one. Guest tests it using
a test and clear operation - this is necessary
so that host can detect interrupt nesting -
and if set, it can skip the EOI MSR.
There's a new MSR to set the address of said register
in guest memory. Otherwise not much changed:
- Guest EOI is not required
- Register is tested & ISR is automatically cleared on exit
For testing results see description of previous patch
'kvm_para: guest side for eoi avoidance'.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index 911d264..851914e 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -517,6 +517,40 @@
__entry->coalesced ? " (coalesced)" : "")
);
+TRACE_EVENT(kvm_eoi,
+ TP_PROTO(struct kvm_lapic *apic, int vector),
+ TP_ARGS(apic, vector),
+
+ TP_STRUCT__entry(
+ __field( __u32, apicid )
+ __field( int, vector )
+ ),
+
+ TP_fast_assign(
+ __entry->apicid = apic->vcpu->vcpu_id;
+ __entry->vector = vector;
+ ),
+
+ TP_printk("apicid %x vector %d", __entry->apicid, __entry->vector)
+);
+
+TRACE_EVENT(kvm_pv_eoi,
+ TP_PROTO(struct kvm_lapic *apic, int vector),
+ TP_ARGS(apic, vector),
+
+ TP_STRUCT__entry(
+ __field( __u32, apicid )
+ __field( int, vector )
+ ),
+
+ TP_fast_assign(
+ __entry->apicid = apic->vcpu->vcpu_id;
+ __entry->vector = vector;
+ ),
+
+ TP_printk("apicid %x vector %d", __entry->apicid, __entry->vector)
+);
+
/*
* Tracepoint for nested VMRUN
*/