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 11F70C43331 for ; Tue, 31 Mar 2020 22:34:11 +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 C284E20842 for ; Tue, 31 Mar 2020 22:34:10 +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="SUMsxQTH" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C284E20842 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]:44770 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jJPST-0004VA-Vl for qemu-devel@archiver.kernel.org; Tue, 31 Mar 2020 18:34:10 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57795) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jJPRL-00044w-6H for qemu-devel@nongnu.org; Tue, 31 Mar 2020 18:33:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jJPRJ-0006RJ-BY for qemu-devel@nongnu.org; Tue, 31 Mar 2020 18:32:58 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:22031 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 1jJPRJ-0006NG-1V for qemu-devel@nongnu.org; Tue, 31 Mar 2020 18:32:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585693976; 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=YTx7isEgpV7I+Ivh50RiItxwua9HQyl9ruPuDi+PRtk=; b=SUMsxQTH43qYO5MSWqEblXmzhyAv/PgBJPjj/rRzqclF0Tk3TtYYB/2IpZ6m1eGI8/bIbN zc7Rfg3hoP4/fyvkvrAFVpYG0IOActiXtOipsqDhaGuDCHRMF3QtgMJxVdk/BtUIvKsLZ6 CRVgVeOplZLWx2x0BOiDuk01WUrQ2Yk= 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-283-md2ZYIjyNcGQQHzq3zQqCQ-1; Tue, 31 Mar 2020 18:32:52 -0400 X-MC-Unique: md2ZYIjyNcGQQHzq3zQqCQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1EB151005509 for ; Tue, 31 Mar 2020 22:32:51 +0000 (UTC) Received: from w520.home (ovpn-112-162.phx2.redhat.com [10.3.112.162]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1BB8D60BE0; Tue, 31 Mar 2020 22:32:45 +0000 (UTC) Date: Tue, 31 Mar 2020 16:32:45 -0600 From: Alex Williamson To: Peter Xu Subject: Re: [PATCH v4 0/5] vfio/pci: Fix up breakage against split irqchip and INTx Message-ID: <20200331163245.74e81595@w520.home> In-Reply-To: <20200318145204.74483-1-peterx@redhat.com> References: <20200318145204.74483-1-peterx@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 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: Eric Auger , Cornelia Huck , qemu-devel@nongnu.org, Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, 18 Mar 2020 10:51:59 -0400 Peter Xu wrote: > v4: > - pick r-b and a-b for Alex without patch 4 > - only kick resamplefd for level triggered irq (as 3.1 change on patch > 4) [Alex] > - fix mingw build error with below squashed into patch 4: IMO, it'd be nice to get this in for QEMU 5.0, were others thinking something different? I provided acks thinking Paolo might take it, but I can send a pull request for it if Paolo wants to ack instead. Thanks, Alex > ---------------------------------------- > diff --git a/hw/intc/ioapic.c b/hw/intc/ioapic.c > index 2ae96e10be..b9ec570c03 100644 > --- a/hw/intc/ioapic.c > +++ b/hw/intc/ioapic.c > @@ -241,6 +241,7 @@ void ioapic_eoi_broadcast(int vector) > continue; > } > > +#ifdef CONFIG_KVM > /* > * When IOAPIC is in the userspace while APIC is still in > * the kernel (i.e., split irqchip), we have a trick to > @@ -257,6 +258,7 @@ void ioapic_eoi_broadcast(int vector) > * emulated devices that are using/sharing the same IRQ. > */ > kvm_resample_fd_notify(n); > +#endif > > if (!(entry & IOAPIC_LVT_REMOTE_IRR)) { > continue; > ---------------------------------------- > > v3: > - collect r-bs for Eric > - unconditionally call kvm_resample_fd_notify(), change comment [Alex] > - remove the split irqchip check in kvm_resample_fd_notify(), then let > it return nothing [Alex] > - test against shared irq to make sure it won't break > > 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 > > 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 | 95 ++++++++++++++++++++++++++++++++++++++---- > accel/kvm/trace-events | 1 + > hw/intc/ioapic.c | 19 +++++++++ > hw/vfio/pci.c | 37 +++++++--------- > include/sysemu/kvm.h | 4 ++ > 5 files changed, 126 insertions(+), 30 deletions(-) >