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 63353C433EF for ; Mon, 3 Jan 2022 08:04:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232020AbiACIEf (ORCPT ); Mon, 3 Jan 2022 03:04:35 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:46328 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230057AbiACIEf (ORCPT ); Mon, 3 Jan 2022 03:04:35 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1641197074; 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=UdxaGBuR9xauk+WHq8djtOf6D/AnMAtrzYys2hrg50c=; b=Enf2PVrqAzN1U1XhH/EQHl2AJz0ZtMJOD7HDMSWY6gyR/7njPtY7LrFfm6K9mcLjrcSZGU 7i4LQ0UIIFdLSUdKaZLI4aaZKWnnXTwqSMMXJspxkUBxH/OoPg5VaIFC5W/Gbg2A2karGi VxzN3YO2h+XJ8hXcaZiJLb5TaP2IyCM= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-609-56YXuo8aMkOOVGn_9Dn9Gg-1; Mon, 03 Jan 2022 03:04:32 -0500 X-MC-Unique: 56YXuo8aMkOOVGn_9Dn9Gg-1 Received: by mail-wr1-f71.google.com with SMTP id s23-20020adf9797000000b001a24674f0f7so10004414wrb.9 for ; Mon, 03 Jan 2022 00:04:32 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=UdxaGBuR9xauk+WHq8djtOf6D/AnMAtrzYys2hrg50c=; b=qxwG8nftDCjV3Irpnq66Br+v4xoWs/ogQYax6UwwmBSmh1/wrVDxjxQnxxDvz5EkW7 yXEMRGn3fMNANpm09jYr+EgC+CtXJa9Sk3luOOMkAwuEL93V8I0MgvzQyFaPqizonjFc ThRSea6B/eZDD/2/rwEjnHGX4+GDq+P2cS5wk5mAOapL5mykTXolM6kuD14NtWlC+Obm x57/gtvv3FIaVCwTsvZZ0XIB0fNxKI2JhlA7TcGmS25+EOxp6lGncXkjeNQTBXUL2HXT 529GDn/AfPDQ3eEh5KWZRtUdEzfBYpiwQxlfo9DLeXQdD/ddd0zHn205cc9NDVRKpX6m kLqQ== X-Gm-Message-State: AOAM533/gAwxNswCOixwSR5J88M7GGLcdwIHgRUiYV/i45VE7HcCDcWW alkLdSVCKjU4YytRcuAOYd1CiVyCbaCkFLoCne5CrsnDx/FYwehw5jmqygWjEaM/Z21yJzXHRcR QF5sELS7i6hoL X-Received: by 2002:a5d:608a:: with SMTP id w10mr36053906wrt.596.1641197071152; Mon, 03 Jan 2022 00:04:31 -0800 (PST) X-Google-Smtp-Source: ABdhPJyVtP/aq31R7doXdWIFuANBoKaaKn+9HxKrxNy2cFus2ZwBwWHx5SjUajR9BsycSue2V/+yEw== X-Received: by 2002:a5d:608a:: with SMTP id w10mr36053893wrt.596.1641197070956; Mon, 03 Jan 2022 00:04:30 -0800 (PST) Received: from fedora (nat-2.ign.cz. [91.219.240.2]) by smtp.gmail.com with ESMTPSA id p18sm4961997wmq.23.2022.01.03.00.04.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Jan 2022 00:04:30 -0800 (PST) From: Vitaly Kuznetsov To: Paolo Bonzini , Igor Mammedov Cc: 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 In-Reply-To: <61325b2b-dc93-5db2-2d0a-dd0900d947f2@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> Date: Mon, 03 Jan 2022 09:04:29 +0100 Message-ID: <87mtkdqm7m.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org 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? -- Vitaly