From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51517) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fuG85-0005x5-9a for qemu-devel@nongnu.org; Mon, 27 Aug 2018 07:56:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fuG7z-0006F2-HJ for qemu-devel@nongnu.org; Mon, 27 Aug 2018 07:56:20 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:34488 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fuG7z-0006Ec-Ah for qemu-devel@nongnu.org; Mon, 27 Aug 2018 07:56:15 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C4009801145A for ; Mon, 27 Aug 2018 11:56:14 +0000 (UTC) From: Igor Mammedov Date: Mon, 27 Aug 2018 13:56:08 +0200 Message-Id: <1535370968-217716-1-git-send-email-imammedo@redhat.com> Subject: [Qemu-devel] [PATCH] vl.c deprecate incorrect CPUs topology List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: pbonzini@redhat.com, libvir-list@redhat.com, ehabkost@redhat.com, berrange@redhat.com, drjones@redhat.com -smp [cpus],sockets/cores/threads[,maxcpus] should describe topology so that total number of logical CPUs [sockets * cores * threads] would be equal to [maxcpus], however historically we didn't have such check in QEMU and it is possible to start VM with an invalid topology. Deprecate invalid options combination so we can make sure that the topology VM started with is always correct in the future. Users with an invalid sockets/cores/threads/maxcpus values should fix their CLI to make sure that [sockets * cores * threads] == [maxcpus] Signed-off-by: Igor Mammedov --- qemu-deprecated.texi | 11 +++++++++++ vl.c | 6 ++++++ 2 files changed, 17 insertions(+) diff --git a/qemu-deprecated.texi b/qemu-deprecated.texi index 87212b6..d5d9ce6 100644 --- a/qemu-deprecated.texi +++ b/qemu-deprecated.texi @@ -159,6 +159,17 @@ The 'file' driver for drives is no longer appropriate for character or host devices and will only accept regular files (S_IFREG). The correct driver for these file types is 'host_cdrom' or 'host_device' as appropriate. +@subsection -smp X,[socket=a,core=b,thread=c],maxcpus=Y (since 3.1) + +CPU topology properties should describe whole machine topology including +possible CPUs. but historically it was possible to start QEMU with +an incorrect topology where + socket * core * thread >= X && < maxcpus +which could lead to incorrect topology enumeration by the guest. +Support for invalid topology will be removed, end user must ensure +that topology described with -smp includes all possible cpus, i.e.: + socket * core * thread == maxcpus + @section QEMU Machine Protocol (QMP) commands @subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0) diff --git a/vl.c b/vl.c index 5ba06ad..bc53828 100644 --- a/vl.c +++ b/vl.c @@ -1238,6 +1238,12 @@ static void smp_parse(QemuOpts *opts) exit(1); } + if (sockets * cores * threads != max_cpus) { + warn_report("Invalid CPUs topology deprecated. " + "sockets (%u) * cores (%u) * threads (%u) " + "!= maxcpus (%u)", + sockets, cores, threads, max_cpus); + } if (sockets * cores * threads > max_cpus) { error_report("cpu topology: " "sockets (%u) * cores (%u) * threads (%u) > " -- 2.7.4