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 3FCEBC433F5 for ; Mon, 3 Jan 2022 09:41:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232120AbiACJlD (ORCPT ); Mon, 3 Jan 2022 04:41:03 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:48028 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231166AbiACJlC (ORCPT ); Mon, 3 Jan 2022 04:41:02 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1641202861; 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=Pfr7nzjNFCMaHerfvymYyqevUR0lJktbumJnTzkRGiY=; b=d7R7U5O8Ydb/fbwOKNzFEZetcMqG2WuF8FESJybgDMDK4CkxWbSZ/SlHYJQxqvd27mtjh1 dvo3CNt9IHrMm0o0w+wThO91xKmcveQAM3GI++5SFnJV1egioo4WK5pE5ng6OlxNKh+ob0 bRq+qwl30IXABxMdKCS50Mt5TOE3h/c= Received: from mail-ed1-f71.google.com (mail-ed1-f71.google.com [209.85.208.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-66-XBFcUvNJMuiI-YCTxzl0Nw-1; Mon, 03 Jan 2022 04:41:00 -0500 X-MC-Unique: XBFcUvNJMuiI-YCTxzl0Nw-1 Received: by mail-ed1-f71.google.com with SMTP id dm10-20020a05640222ca00b003f808b5aa18so22482707edb.4 for ; Mon, 03 Jan 2022 01:41:00 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=Pfr7nzjNFCMaHerfvymYyqevUR0lJktbumJnTzkRGiY=; b=ecv9nF0ThHh6KP7S4SvVSLPKaVoS+Er2NljBmUif3MPWJR2gSo2vZ+negKifuW+PNg zBPfKKDt7pNnx5B9fQ3/9j6MND/6bU/WIjRV6/RBdbxpEuiHM+Vj1+FS5Y2NynntDTu5 T2lsOSFRDo3yV8VZU99kdcU6Q34A1+rbTwhU/iKj10L6ZYDxpXwYOILEl39TS9u2VZII z+wCXDW3pFKSZrumafO57KNkabE5W9LUNJn99GIe/3sc3SLL34dS/LPIJ3NaPwu/AeHb hZKiiER816KScVOppsKCipFNuSJViLb34KgQ9MjhHEWIjovitZ2rkkUD92ew2gZj4mCD mnTQ== X-Gm-Message-State: AOAM531qyFc+ov42AQsNiZ9kHBb0huB8c2KZvlP1P3D23D3Recq1sqqd SbISBhR2+j4rz+Gf2bd1qb/naWY1qJUJeSyCiKoFRDtcr0dXmo/lJ5ILM2q1zouRflvFxtiNpwc PaV4IIh2DapCl X-Received: by 2002:a17:906:4556:: with SMTP id s22mr35523717ejq.321.1641202859480; Mon, 03 Jan 2022 01:40:59 -0800 (PST) X-Google-Smtp-Source: ABdhPJzXmWc00Q66qCcpRjKVdNxzVhgAFaMG4VaaflGAUbiOtR2hHa0IcoUhFH7h5Bg7+RnOY0i0Rw== X-Received: by 2002:a17:906:4556:: with SMTP id s22mr35523700ejq.321.1641202859270; Mon, 03 Jan 2022 01:40:59 -0800 (PST) Received: from localhost (nat-pool-brq-u.redhat.com. [213.175.37.12]) by smtp.gmail.com with ESMTPSA id s3sm2168691ejs.145.2022.01.03.01.40.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Jan 2022 01:40:58 -0800 (PST) Date: Mon, 3 Jan 2022 10:40:57 +0100 From: Igor Mammedov To: Vitaly Kuznetsov Cc: Paolo Bonzini , kvm@vger.kernel.org, Sean Christopherson , Wanpeng Li , Jim Mattson , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] KVM: x86: Forbid KVM_SET_CPUID{,2} after KVM_RUN Message-ID: <20220103104057.4dcf7948@redhat.com> In-Reply-To: <87mtkdqm7m.fsf@redhat.com> References: <20211122175818.608220-1-vkuznets@redhat.com> <20211122175818.608220-3-vkuznets@redhat.com> <16368a89-99ea-e52c-47b6-bd006933ec1f@redhat.com> <20211227183253.45a03ca2@redhat.com> <61325b2b-dc93-5db2-2d0a-dd0900d947f2@redhat.com> <87mtkdqm7m.fsf@redhat.com> X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.30; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, 03 Jan 2022 09:04:29 +0100 Vitaly Kuznetsov wrote: > Paolo Bonzini writes: > > > On 12/27/21 18:32, Igor Mammedov wrote: > >>> Tweaked and queued nevertheless, thanks. > >> it seems this patch breaks VCPU hotplug, in scenario: > >> > >> 1. hotunplug existing VCPU (QEMU stores VCPU file descriptor in parked cpus list) > >> 2. hotplug it again (unsuspecting QEMU reuses stored file descriptor when recreating VCPU) > >> > >> RHBZ:https://bugzilla.redhat.com/show_bug.cgi?id=2028337#c11 > >> > > > > The fix here would be (in QEMU) to not call KVM_SET_CPUID2 again. > > However, we need to work around it in KVM, and allow KVM_SET_CPUID2 if > > the data passed to the ioctl is the same that was set before. > > Are we sure the data is going to be *exactly* the same? In particular, > when using vCPU fds from the parked list, do we keep the same > APIC/x2APIC id when hotplugging? Or can we actually hotplug with a > different id? If I recall it right, it can be a different ID easily.