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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30D24C433F5 for ; Wed, 19 Jan 2022 14:38:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355173AbiASOiG (ORCPT ); Wed, 19 Jan 2022 09:38:06 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:59178 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355162AbiASOiG (ORCPT ); Wed, 19 Jan 2022 09:38:06 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1642603085; 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: in-reply-to:in-reply-to:references:references; bh=a01rUYdHW+bO+StXD3HoNzD8eXkiC4JLXNvROzx2a7U=; b=SlyMPt24v6za0oUiPizF+7UB/ZPjNEqHQTTCIj3F4ANFnXxMaHXqAb1L4USsYE39sJgwv2 vLC++BqPNl/6H4dUG12FzVYc7Ua35aZkIv1JY4qWfwKZyFM4yDFtRr9ULurIl9U7ujcMsY Nmh6Qy/CplqQURXIEKpTZETAvEpPG9E= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-86-eqE4JhtINsCAlUEDJ6gAjw-1; Wed, 19 Jan 2022 09:38:02 -0500 X-MC-Unique: eqE4JhtINsCAlUEDJ6gAjw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B8C0E802924; Wed, 19 Jan 2022 14:38:00 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-112-16.ams2.redhat.com [10.36.112.16]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D55037E64B; Wed, 19 Jan 2022 14:37:55 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 6608F113865F; Wed, 19 Jan 2022 15:37:54 +0100 (CET) From: Markus Armbruster To: Vladimir Sementsov-Ogievskiy Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org, lvivier@redhat.com, thuth@redhat.com, mtosatti@redhat.com, pbonzini@redhat.com, richard.henderson@linaro.org, eblake@redhat.com, philmd@redhat.com, marcel.apfelbaum@gmail.com, eduardo@habkost.net, den@openvz.org, valery.vdovin.s@gmail.com, Valeriy Vdovin Subject: Re: [PATCH v16] qapi: introduce 'x-query-x86-cpuid' QMP command. References: <20211222123124.130107-1-vsementsov@virtuozzo.com> Date: Wed, 19 Jan 2022 15:37:54 +0100 In-Reply-To: <20211222123124.130107-1-vsementsov@virtuozzo.com> (Vladimir Sementsov-Ogievskiy's message of "Wed, 22 Dec 2021 13:31:24 +0100") Message-ID: <87lezbdc59.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Vladimir Sementsov-Ogievskiy writes: > From: Valeriy Vdovin > > Introducing new QMP command 'query-x86-cpuid'. This command can be used to > get virtualized cpu model info generated by QEMU during VM initialization in > the form of cpuid representation. > > Diving into more details about virtual CPU generation: QEMU first parses '-cpu' > command line option. From there it takes the name of the model as the basis for > feature set of the new virtual CPU. After that it uses trailing '-cpu' options, > that state if additional cpu features should be present on the virtual CPU or > excluded from it (tokens '+'/'-' or '=on'/'=off'). > After that QEMU checks if the host's cpu can actually support the derived > feature set and applies host limitations to it. > After this initialization procedure, virtual CPU has it's model and > vendor names, and a working feature set and is ready for identification > instructions such as CPUID. > > To learn exactly how virtual CPU is presented to the guest machine via CPUID > instruction, new QMP command can be used. By calling 'query-x86-cpuid' > command, one can get a full listing of all CPUID leaves with subleaves which are > supported by the initialized virtual CPU. > > Other than debug, the command is useful in cases when we would like to > utilize QEMU's virtual CPU initialization routines and put the retrieved > values into kernel CPUID overriding mechanics for more precise control > over how various processes perceive its underlying hardware with > container processes as a good example. > > The command is specific to x86. It is currenly only implemented for KVM acceleator. Please wrap your commit messages around column 70. > > Output format: > The output is a plain list of leaf/subleaf argument combinations, that > return 4 words in registers EAX, EBX, ECX, EDX. > > Use example: > qmp_request: { > "execute": "x-query-x86-cpuid" > } > > qmp_response: { > "return": [ > { > "eax": 1073741825, > "edx": 77, > "in-eax": 1073741824, > "ecx": 1447775574, > "ebx": 1263359563 > }, > { > "eax": 16777339, > "edx": 0, > "in-eax": 1073741825, > "ecx": 0, > "ebx": 0 > }, > { > "eax": 13, > "edx": 1231384169, > "in-eax": 0, > "ecx": 1818588270, > "ebx": 1970169159 > }, > { > "eax": 198354, > "edx": 126614527, > "in-eax": 1, > "ecx": 2176328193, > "ebx": 2048 > }, > .... > { > "eax": 12328, > "edx": 0, > "in-eax": 2147483656, > "ecx": 0, > "ebx": 0 > } > ] > } > > Signed-off-by: Valeriy Vdovin > Signed-off-by: Vladimir Sementsov-Ogievskiy This needs review from x86 CPU maintainers. Eduardo? [...] > diff --git a/qapi/machine-target.json b/qapi/machine-target.json > index f5ec4bc172..0ac575b1b9 100644 > --- a/qapi/machine-target.json > +++ b/qapi/machine-target.json > @@ -341,3 +341,49 @@ > 'TARGET_I386', > 'TARGET_S390X', > 'TARGET_MIPS' ] } } > + > +## > +# @CpuidEntry: > +# > +# A single entry of a CPUID response. > +# > +# One entry holds full set of information (leaf) returned to the guest > +# in response to it calling a CPUID instruction with eax, ecx used as > +# the arguments to that instruction. ecx is an optional argument as > +# not all of the leaves support it. > +# > +# @in-eax: CPUID argument in eax > +# @in-ecx: CPUID argument in ecx > +# @eax: CPUID result in eax > +# @ebx: CPUID result in ebx > +# @ecx: CPUID result in ecx > +# @edx: CPUID result in edx > +# > +# Since: 7.0 > +## > +{ 'struct': 'CpuidEntry', > + 'data': { 'in-eax' : 'uint32', > + '*in-ecx' : 'uint32', > + 'eax' : 'uint32', > + 'ebx' : 'uint32', > + 'ecx' : 'uint32', > + 'edx' : 'uint32' > + }, > + 'if': 'TARGET_I386' } > + > +## > +# @x-query-x86-cpuid: > +# > +# Returns raw data from the emulated CPUID table for the first VCPU. > +# The emulated CPUID table defines the response to the CPUID > +# instruction when executed by the guest operating system. > +# > +# > +# Returns: a list of CpuidEntry. Returns error when qemu is configured with > +# --disable-kvm flag or if qemu is run with any other accelerator than KVM. Long line, please wrap around column 70. > +# > +# Since: 7.0 > +## > +{ 'command': 'x-query-x86-cpuid', > + 'returns': ['CpuidEntry'], > + 'if': 'TARGET_I386' } Needs feature 'unstable' now; see commit a3c45b3e62 'qapi: New special feature flag "unstable"' and also commit 57df0dff1a "qapi: Extend -compat to set policy for unstable interfaces". Incremental patch appended for your convenience. diff --git a/qapi/machine-target.json b/qapi/machine-target.json index 0ac575b1b9..049fa48a35 100644 --- a/qapi/machine-target.json +++ b/qapi/machine-target.json @@ -378,6 +378,8 @@ # The emulated CPUID table defines the response to the CPUID # instruction when executed by the guest operating system. # +# Features: +# @unstable: This command is experimental. # # Returns: a list of CpuidEntry. Returns error when qemu is configured with # --disable-kvm flag or if qemu is run with any other accelerator than KVM. @@ -386,4 +388,5 @@ ## { 'command': 'x-query-x86-cpuid', 'returns': ['CpuidEntry'], - 'if': 'TARGET_I386' } + 'if': 'TARGET_I386', + 'features': [ 'unstable' ] }