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kvm/x86: implement hv EOI assist

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It seems that it's easy to implement the EOI assist
on top of the PV EOI feature: simply convert the
page address to the format expected by PV EOI.

Notes:
-"No EOI required" is set only if interrupt injected
 is edge triggered; this is true because level interrupts are going
 through IOAPIC which disables PV EOI.
 In any case, if guest triggers EOI the bit will get cleared on exit.
-For migration, set of HV_X64_MSR_APIC_ASSIST_PAGE sets
 KVM_PV_EOI_EN internally, so restoring HV_X64_MSR_APIC_ASSIST_PAGE
 seems sufficient
 In any case, bit is cleared on exit so worst case it's never re-enabled
-no handling of PV EOI data is performed at HV_X64_MSR_EOI write;
 HV_X64_MSR_EOI is a separate optimization - it's an X2APIC
 replacement that lets you do EOI with an MSR and not IO.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2014-05-07 16:29:48 +03:00 committed by Paolo Bonzini
parent 5f7dde7bbb
commit b63cf42fd1
1 changed files with 4 additions and 0 deletions
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4
arch/x86/kvm/x86.c
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@ -1917,6 +1917,8 @@ static int set_msr_hyperv(struct kvm_vcpu *vcpu, u32 msr, u64 data)
if (!(data & HV_X64_MSR_APIC_ASSIST_PAGE_ENABLE)) {
vcpu->arch.hv_vapic = data;
if (kvm_lapic_enable_pv_eoi(vcpu, 0))
return 1;
break;
}
gfn = data >> HV_X64_MSR_APIC_ASSIST_PAGE_ADDRESS_SHIFT;
@ -1927,6 +1929,8 @@ static int set_msr_hyperv(struct kvm_vcpu *vcpu, u32 msr, u64 data)
return 1;
vcpu->arch.hv_vapic = data;
mark_page_dirty(vcpu->kvm, gfn);
if (kvm_lapic_enable_pv_eoi(vcpu, gfn_to_gpa(gfn) | KVM_MSR_ENABLED))
return 1;
break;
}
case HV_X64_MSR_EOI: