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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 8394AC47083 for ; Wed, 2 Jun 2021 20:47:03 +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 D860B61040 for ; Wed, 2 Jun 2021 20:47:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D860B61040 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]:41900 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1loXlV-0003dv-SG for qemu-devel@archiver.kernel.org; Wed, 02 Jun 2021 16:47:01 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51290) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1loXkk-0002ip-6y for qemu-devel@nongnu.org; Wed, 02 Jun 2021 16:46:14 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:48676) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1loXkf-0003FZ-P6 for qemu-devel@nongnu.org; Wed, 02 Jun 2021 16:46:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1622666767; 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=MaJkGqCRd62/z/KrcCCUMeTbWp2LlOC2T7zrXxn/tg8=; b=QvKC9DiHIwTfHGYpkeQhmXm97YJ6FCFENDvWtO+3jqgLrcxdrhjnvo93migvxjpyKwQjEH uSPJbkVerDp8wLIvjPD0nj5CfU2Wnqrex5yTgdiUdnO+S1o4IZ1n4jTPNievAyfiwxOn+i LoLaOD1X/FANfSp57R0FlnEnuyDqaa8= 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-238-ftUovkHqOzyTza5n908Vqw-1; Wed, 02 Jun 2021 16:46:06 -0400 X-MC-Unique: ftUovkHqOzyTza5n908Vqw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1D2048030A1; Wed, 2 Jun 2021 20:46:05 +0000 (UTC) Received: from localhost (ovpn-119-154.rdu2.redhat.com [10.10.119.154]) by smtp.corp.redhat.com (Postfix) with ESMTP id B4FA5687F6; Wed, 2 Jun 2021 20:46:04 +0000 (UTC) Date: Wed, 2 Jun 2021 16:46:04 -0400 From: Eduardo Habkost To: Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Subject: Re: [PATCH v8] qapi: introduce 'query-kvm-cpuid' action Message-ID: <20210602204604.crsxvqixkkll4ef4@habkost.net> References: <20210531123806.23030-1-valeriy.vdovin@virtuozzo.com> <266974fa-da6c-d0fc-ce12-6a7ce1752fa6@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <266974fa-da6c-d0fc-ce12-6a7ce1752fa6@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Received-SPF: pass client-ip=170.10.133.124; envelope-from=ehabkost@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.371, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: Laurent Vivier , Thomas Huth , Vladimir Sementsov-Ogievskiy , kvm@vger.kernel.org, Marcelo Tosatti , Richard Henderson , Markus Armbruster , qemu-devel@nongnu.org, Valeriy Vdovin , Denis Lunev , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Jun 02, 2021 at 08:17:28PM +0200, Philippe Mathieu-Daudé wrote: > Hi Valeriy, > > (Sorry for not looking earlier than v8) > > On 5/31/21 2:38 PM, Valeriy Vdovin wrote: > > Introducing new qapi method 'query-kvm-cpuid'. This method 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. > > > > Currently full output for this method is only supported for x86 cpus. > > > > To learn exactly how virtual cpu is presented to the guest machine via CPUID > > instruction, new qapi method can be used. By calling 'query-kvm-cpuid' > > method, one can get a full listing of all CPUID leafs with subleafs which are > > supported by the initialized virtual cpu. > > > > Other than debug, the method 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. > > > > Output format: > > The output is a plain list of leaf/subleaf agrument combinations, that > > return 4 words in registers EAX, EBX, ECX, EDX. > > > > Use example: > > qmp_request: { > > "execute": "query-kvm-cpuid" > > } > > > > qmp_response: [ > > { > > "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, > > .... > > > > Signed-off-by: Valeriy Vdovin > > --- > > > > > v2: - Removed leaf/subleaf iterators. > > - Modified cpu_x86_cpuid to return false in cases when count is > > greater than supported subleaves. > > v3: - Fixed structure name coding style. > > - Added more comments > > - Ensured buildability for non-x86 targets. > > v4: - Fixed cpu_x86_cpuid return value logic and handling of 0xA leaf. > > - Fixed comments. > > - Removed target check in qmp_query_cpu_model_cpuid. > > v5: - Added error handling code in qmp_query_cpu_model_cpuid > > v6: - Fixed error handling code. Added method to query_error_class > > v7: - Changed implementation in favor of cached cpuid_data for > > KVM_SET_CPUID2 > > v8: - Renamed qmp method to query-kvm-cpuid and some fields in response. > > - Modified documentation to qmp method > > - Removed helper struct declaration > > --- > > ^ Below this '---' go your comments. > > > qapi/machine-target.json | 43 ++++++++++++++++++++++++++++++++++++++ > > target/i386/kvm/kvm.c | 37 ++++++++++++++++++++++++++++++++ > > tests/qtest/qmp-cmd-test.c | 1 + > > 3 files changed, 81 insertions(+) > > > > diff --git a/qapi/machine-target.json b/qapi/machine-target.json > > index e7811654b7..a83180dd24 100644 > > --- a/qapi/machine-target.json > > +++ b/qapi/machine-target.json > > @@ -329,3 +329,46 @@ > > ## > > { 'command': 'query-cpu-definitions', 'returns': ['CpuDefinitionInfo'], > > 'if': 'defined(TARGET_PPC) || defined(TARGET_ARM) || defined(TARGET_I386) || defined(TARGET_S390X) || defined(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 agruments 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: eax > > +# @ebx: ebx > > +# @ecx: ecx > > +# @edx: edx > > +# > > +# Since: 6.1 > > +## > > +{ 'struct': 'CpuidEntry', > > + 'data': { 'in_eax' : 'uint32', > > + '*in_ecx' : 'uint32', > > + 'eax' : 'uint32', > > + 'ebx' : 'uint32', > > + 'ecx' : 'uint32', > > + 'edx' : 'uint32' > > + }, > > + 'if': 'defined(TARGET_I386) && defined(CONFIG_KVM)' } > > What about other accelerators? > > > + > > +## > > +# @query-kvm-cpuid: > > +# > > +# Returns raw data from the KVM CPUID table for the first VCPU. > > +# The KVM CPUID table defines the response to the CPUID > > +# instruction when executed by the guest operating system. > > What is specific to KVM here? > > What about 'query-accel-cpuid' or 'query-vm-cpu-id'? The implementation is KVM-specific. I believe it's a reasonable compromise because the implementation is trivial, and a raw copy of the KVM CPUID table makes it a more useful (KVM-specific) debugging/testing mechanism. I don't really mind how the command is called, but I would prefer to add a more complex abstraction only if maintainers of other accelerators are interested and volunteer to provide similar functionality. I don't want to introduce complexity for use cases that may not even exist. > > > +# > > +# Returns: a list of CpuidEntry > > +# > > +# Since: 6.1 > > +## > > +{ 'command': 'query-kvm-cpuid', > > + 'returns': ['CpuidEntry'], > > + 'if': 'defined(TARGET_I386) && defined(CONFIG_KVM)' } > ... > > diff --git a/tests/qtest/qmp-cmd-test.c b/tests/qtest/qmp-cmd-test.c > > index c98b78d033..48add3ada1 100644 > > --- a/tests/qtest/qmp-cmd-test.c > > +++ b/tests/qtest/qmp-cmd-test.c > > @@ -46,6 +46,7 @@ static int query_error_class(const char *cmd) > > { "query-balloon", ERROR_CLASS_DEVICE_NOT_ACTIVE }, > > { "query-hotpluggable-cpus", ERROR_CLASS_GENERIC_ERROR }, > > { "query-vm-generation-id", ERROR_CLASS_GENERIC_ERROR }, > > + { "query-kvm-cpuid", ERROR_CLASS_GENERIC_ERROR }, > > { NULL, -1 } > > }; > > int i; > > > -- Eduardo