From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E53CFC10F27 for ; Tue, 10 Mar 2020 01:55:06 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B170424649 for ; Tue, 10 Mar 2020 01:55:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="bcDl1Pzx" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B170424649 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:52404 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jBU6r-00080F-Uz for qemu-devel@archiver.kernel.org; Mon, 09 Mar 2020 21:55:05 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43730) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jBU6C-0007bf-Jp for qemu-devel@nongnu.org; Mon, 09 Mar 2020 21:54:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jBU6B-0008BB-2D for qemu-devel@nongnu.org; Mon, 09 Mar 2020 21:54:24 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:60369 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jBU6A-0008AV-T1 for qemu-devel@nongnu.org; Mon, 09 Mar 2020 21:54:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1583805262; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=oI3v1/aJnAwBaOGVd8qwLyx3qCTl0MjmDa90xPuSLaE=; b=bcDl1PzxFVtQxNesmkU896UQQpKqWefUkiZqLzQXlVtV4BeoTYjn84Ujl9OA6dcZZTuA75 Hd7Fbtczxb0Rr/CMqSUXkjC3wTDukoHjh54dfD9IhvBsZjX+8q1/v6y4QtmbzB7recVF7P tbYplq7h9uQU5syOGaL0FX9Ctcnr1PY= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-121-OXgBBZgoNzSV1AZOb0jcJw-1; Mon, 09 Mar 2020 21:54:18 -0400 X-MC-Unique: OXgBBZgoNzSV1AZOb0jcJw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B38CE8017CC for ; Tue, 10 Mar 2020 01:54:17 +0000 (UTC) Received: from x1.home (ovpn-116-28.phx2.redhat.com [10.3.116.28]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5038A5C1C3; Tue, 10 Mar 2020 01:54:11 +0000 (UTC) Date: Mon, 9 Mar 2020 19:54:10 -0600 From: Alex Williamson To: Peter Xu Subject: Re: [PATCH v2 4/5] KVM: Kick resamplefd for split kernel irqchip Message-ID: <20200309195410.7946c02c@x1.home> In-Reply-To: <20200310003808.GC326977@xz-x1> References: <20200228161503.382656-1-peterx@redhat.com> <20200228161503.382656-5-peterx@redhat.com> <20200309161059.7c1cc49e@w520.home> <20200309163359.45ac9c3e@w520.home> <20200310003808.GC326977@xz-x1> Organization: Red Hat MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paolo Bonzini , Cornelia Huck , qemu-devel@nongnu.org, Eric Auger Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, 9 Mar 2020 20:38:08 -0400 Peter Xu wrote: > On Mon, Mar 09, 2020 at 04:33:59PM -0600, Alex Williamson wrote: > > [...] > > > > > diff --git a/hw/intc/ioapic.c b/hw/intc/ioapic.c > > > > index 15747fe2c2..13921b333d 100644 > > > > --- a/hw/intc/ioapic.c > > > > +++ b/hw/intc/ioapic.c > > > > @@ -236,8 +236,27 @@ void ioapic_eoi_broadcast(int vector) > > > > for (n = 0; n < IOAPIC_NUM_PINS; n++) { > > > > entry = s->ioredtbl[n]; > > > > > > > > - if ((entry & IOAPIC_VECTOR_MASK) != vector || > > > > - ((entry >> IOAPIC_LVT_TRIGGER_MODE_SHIFT) & 1) != IOAPIC_TRIGGER_LEVEL) { > > > > + if ((entry & IOAPIC_VECTOR_MASK) != vector) { > > > > + continue; > > > > + } > > > > + > > > > + /* > > > > + * When IOAPIC is in the userspace while APIC is still in > > > > + * the kernel (i.e., split irqchip), we have a trick to > > > > + * kick the resamplefd logic for registered irqfds from > > > > + * userspace to deactivate the IRQ. When that happens, it > > > > + * means the irq bypassed userspace IOAPIC (so the irr and > > > > + * remote-irr of the table entry should be bypassed too > > > > + * even if interrupt come), then we don't need to clear > > > > + * the remote-IRR and check irr again because they'll > > > > + * always be zeros. > > > > + */ > > > > + if (kvm_resample_fd_notify(n)) { > > > > + continue; > > > > + } > > > > > > It seems the problem I reported is here. In my configuration virtio-blk > > > and an assigned e1000e share an interrupt. virtio-blk is initializing > > > and apparently triggers an interrupt. The vfio-pci device is > > > configured for INTx though not active yet, but kvm_resample_fd_notify() > > > kicks the fd here, so we continue. If I remove the continue here both > > > devices seem to work, but I don't claim to understand the condition > > > we're trying to continue for here yet. This series needs more testing > > > with shared interrupts. Thanks, > > > > I'm also curious how this ended up between testing whether the vector > > is masked and testing that it's level triggered. We shouldn't have any > > edge triggered resamplers. > > We had a similar discussion in V1 (with Paolo): > > https://patchwork.kernel.org/patch/11407441/#23190891 > > So my understanding is that VFIO will unmask the intx IRQ when it > comes, and register the resamplefd too, no matter whether it's level > triggered (at least from what the code does). Am I right? As Paolo replied in your previous discussion, INTx is always level triggered. > > I find however that if I move the resampler > > notify to after the remote IRR test, my NIC gets starved of interrupts. > > So empirically, it seems kvm_resample_fd_notify() should be a void > > function called unconditionally between the original mask+level check > > removed above and the IRR check below. Thanks, > > Yes IMHO we can't move that notify() to be after the remote IRR check > because the IRR and remote IRR will be completely bypassed for the > assigned device. In other words, even if the interrupt has arrived > for the assigned device, both IRR and remote IRR should always be zero > (assuming the virtio-blk device doesn't generate any IRQ). So we > probably still need to do the notify even if remote-irr is not set. Yep. Thanks, Alex