From mboxrd@z Thu Jan 1 00:00:00 1970 From: Radim =?utf-8?B?S3LEjW3DocWZ?= Subject: Re: [PATCH] KVM: x86: don't notify userspace IOAPIC on edge EOI Date: Thu, 8 Oct 2015 20:34:54 +0200 Message-ID: <20151008183453.GD4508@potion.brq.redhat.com> References: <1444329000-8723-1-git-send-email-rkrcmar@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: kvm@vger.kernel.org, Paolo Bonzini , Steve Rutherford To: linux-kernel@vger.kernel.org Return-path: Content-Disposition: inline In-Reply-To: <1444329000-8723-1-git-send-email-rkrcmar@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 2015-10-08 20:30+0200, Radim Kr=C4=8Dm=C3=A1=C5=99: > 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. >=20 > 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. >=20 > Signed-off-by: Radim Kr=C4=8Dm=C3=A1=C5=99 > --- > Completely untested. > =20 > 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 *vc= pu, u64 *eoi_exit_bitmap) > for (i =3D 0; i < nr_ioapic_pins; ++i) { > hlist_for_each_entry(entry, &table->map[i], link) { > u32 dest_id, dest_mode; > + bool level; > =20 > if (entry->type !=3D KVM_IRQ_ROUTING_MSI) > continue; > dest_id =3D (entry->msi.address_lo >> 12) & 0xff; > dest_mode =3D (entry->msi.address_lo >> 2) & 0x1; > - if (kvm_apic_match_dest(vcpu, NULL, 0, dest_id, > - dest_mode)) { > + level =3D 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.