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SubjectRe: [PATCH] KVM: x86: don't notify userspace IOAPIC on edge EOI
2015-10-08 20:30+0200, Radim Krčmář:
> On real hardware, edge-triggered interrupts don't set a bit in TMR,
> which means that IOAPIC isn't notified on EOI. Do the same here.
>
> Staying in guest/kernel mode after edge EOI is what we want for most
> devices. If some bugs could be nicely worked around with edge EOI
> notifications, we should invest in a better interface.
>
> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
> ---
> Completely untested.
>
> diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c
> @@ -389,13 +389,15 @@ void kvm_scan_ioapic_routes(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap)
> for (i = 0; i < nr_ioapic_pins; ++i) {
> hlist_for_each_entry(entry, &table->map[i], link) {
> u32 dest_id, dest_mode;
> + bool level;
>
> if (entry->type != KVM_IRQ_ROUTING_MSI)
> continue;
> dest_id = (entry->msi.address_lo >> 12) & 0xff;
> dest_mode = (entry->msi.address_lo >> 2) & 0x1;
> - if (kvm_apic_match_dest(vcpu, NULL, 0, dest_id,
> - dest_mode)) {
> + level = entry->msi.data & MSI_DATA_TRIGGER_LEVEL;
> + if (level && kvm_apic_match_dest(vcpu, NULL, 0,

Describing that result is an overkill -- I'll send v2 if the idea is
accepted.


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