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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 EA374C3F2CD for ; Mon, 2 Mar 2020 15:11:28 +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 B4E4C2146E for ; Mon, 2 Mar 2020 15:11:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="adBbp1J4" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B4E4C2146E 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]:33848 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j8mj9-0006MI-W4 for qemu-devel@archiver.kernel.org; Mon, 02 Mar 2020 10:11:28 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:37605) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j8mi3-0005On-SJ for qemu-devel@nongnu.org; Mon, 02 Mar 2020 10:10:21 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j8mi2-0003tX-JF for qemu-devel@nongnu.org; Mon, 02 Mar 2020 10:10:19 -0500 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:25459 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 1j8mi2-0003t9-EV for qemu-devel@nongnu.org; Mon, 02 Mar 2020 10:10:18 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1583161817; 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=PNix4A4drFTzRf6rvfVEOs/bmCR/EkjR6i/NDRTXRSs=; b=adBbp1J4g1ZyNTqZweuj0iidv61dzPCBhRYzAd/cVwdI9MEMQJMPoq8C5uyLMF0kCFFvdh k85BoDSi6pO+CtZ6UJwNgHKna/PT7lr0gO7p3AbBlqNkamcRTczLDcvLMmKHElr3KM7YVF 1ETZhgs9Do/AKvugmkDwlSsEcxhbtDA= 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-209-DsDYW7TLOmuuRVTahU-MJw-1; Mon, 02 Mar 2020 10:10:15 -0500 X-MC-Unique: DsDYW7TLOmuuRVTahU-MJw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5DE5910753FE for ; Mon, 2 Mar 2020 15:10:14 +0000 (UTC) Received: from [10.36.116.59] (ovpn-116-59.ams2.redhat.com [10.36.116.59]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EE91A7386E; Mon, 2 Mar 2020 15:10:01 +0000 (UTC) Subject: Re: [PATCH v2 0/5] vfio/pci: Fix up breakage against split irqchip and INTx To: Peter Xu , qemu-devel@nongnu.org References: <20200228161503.382656-1-peterx@redhat.com> From: Auger Eric Message-ID: Date: Mon, 2 Mar 2020 16:09:59 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20200228161503.382656-1-peterx@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 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 , Alex Williamson , Cornelia Huck Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Peter, On 2/28/20 5:14 PM, Peter Xu wrote: > v2: > - pick tags > - don't register resamplefd with KVM kernel when the userspace > resamplefd path is enabled (should enable fast path on new kernels) > - fix resamplefd mem leak > - fix commit message of patch 4 [Eric] > - let kvm_resample_fd_notify() return a boolean, skip ioapic check if > returned true > - more comments here and there in the code to state the fact that > userspace ioapic irr & remote-irr are bypassed [Paolo] > > VFIO INTx is not working with split irqchip. On new kernels KVM_IRQFD > will directly fail with resamplefd attached so QEMU will automatically > fallback to the INTx slow path. However on old kernels it's still > broken. > > Only until recently I noticed that this could also break PXE boot for > assigned NICs [1]. My wild guess is that the PXE ROM will be mostly > using INTx as well, which means we can't bypass that even if we > enables MSI for the guest kernel. > > This series tries to first fix this issue function-wise, then speed up > for the INTx again with resamplefd (mostly following the ideas > proposed by Paolo one year ago [2]). My TCP_RR test shows that: > > - Before this series: this is broken, no number to show > > - After patch 1 (enable slow path): get 63% perf comparing to full > kernel irqchip > > - After whole series (enable fast path partly, irq injection will be > the same as fast path, however userspace needs to intercept for > EOI broadcast to resamplefd, though should still be faster than > the MMIO trick for intx eoi): get 93% perf comparing to full > kernel irqchip, which is a 46% performance boost > > I think we can consider to apply patch 1 even sooner than the rest of > the series to unbreak intx+split first. > > The whole test matrix for reference: > > |----------+---------+-------------------+--------------+--------------------| > | IRQ type | irqchip | TCP_STREAM (Gbps) | TCP_RR (pps) | note | > |----------+---------+-------------------+--------------+--------------------| > | msi | on | 9.39 | 17567 | | > | nomsi | on | 9.29 | 14056 | | > | msi | split | 9.36 | 17330 | | > | nomsi | split | / | / | currently broken | > | nomsi | split | 8.98 | 8977 | after patch 1 | > | nomsi | split | 9.21 | 13142 | after whole series | > |----------+---------+-------------------+--------------+--------------------| > > Any review comment is welcomed. Thanks, > > [1] https://bugzilla.redhat.com/show_bug.cgi?id=1786404 > [2] https://patchwork.kernel.org/patch/10738541/#22609933 For the whole series: Tested-by: Eric Auger using a 5.2-rc1 kernel with reverted "654f1f13ea56 kvm: Check irqchip mode before assign irqfd" and guest booting with nomsi. Thanks Eric > > Peter Xu (5): > vfio/pci: Disable INTx fast path if using split irqchip > vfio/pci: Use kvm_irqchip_add_irqfd_notifier_gsi() for irqfds > KVM: Pass EventNotifier into kvm_irqchip_assign_irqfd > KVM: Kick resamplefd for split kernel irqchip > Revert "vfio/pci: Disable INTx fast path if using split irqchip" > > accel/kvm/kvm-all.c | 101 +++++++++++++++++++++++++++++++++++++---- > accel/kvm/trace-events | 1 + > hw/intc/ioapic.c | 23 +++++++++- > hw/vfio/pci.c | 37 ++++++--------- > include/sysemu/kvm.h | 7 +++ > 5 files changed, 137 insertions(+), 32 deletions(-) >