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 5C883C433FE for ; Mon, 3 Jan 2022 08:04:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232077AbiACIEh (ORCPT ); Mon, 3 Jan 2022 03:04:37 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:36690 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230057AbiACIEg (ORCPT ); Mon, 3 Jan 2022 03:04:36 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1641197075; 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=QtGxKdkJvuoiHKczHSfgr3AYLT9wt15yrq7sI0sEkGidT4RkwSEUmfvKzYGbTJX2EQcb+F pzXPjS8jpSz5fQ++GJSnflPObrR0+mPMhLzofmGmj00UhltDz64BJeb8/UZQn/MjOjyPBZ f2vrIC31HhsZjD4/qEmmidqQScwVIzI= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-231-7BPCJbh0OQKoK9XPUB9hlg-1; Mon, 03 Jan 2022 03:04:32 -0500 X-MC-Unique: 7BPCJbh0OQKoK9XPUB9hlg-1 Received: by mail-wr1-f72.google.com with SMTP id w25-20020adf8bd9000000b001a255212b7cso9951636wra.18 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=YQxmMHCoXO2JQ7xqRiObFs4D6rXjx3dDiSB+Huc/ZP9IVg0YOSKDbPvkN69sE4Z/dF Vmow9BJN5oSL1sTJcObyn2nY2jmV1brPk1STA16jh2oD2e+1hRVpMhKCnIvA2JvBRk4R CtrMzQ4jkQxXDlnputpT6ypnGRBaiZbBjIzo3MY5V1xcrPmLyw+bCCCS5TbbXcDaE4XT i9h4i1SUOukK57D4rLK717SjPChPP/9XUFF7hMy6Ags0d8Ulh0RLDiIF+c68xCn9jHtZ LF2vjEkO7F7+HO4VDRYMt5sQW25WAMjx14VuIZy4mMes8Nca4VsaEtxjZxmEyChT/huL RdPQ== X-Gm-Message-State: AOAM531d8IrEJIBnycjjjksIbGICSb8UeQ5E55zYK9Cflq/uU7yYcohr KMK7x0zEB5xAX1Ml95vXisl/5PGNffhEWqdD+fyEOonr3U+85OptqcpnuS+Zzh7uzL3yVz7XlM4 4E1rpwlI5/J1s/Dm6VPHGhC85mAwaWmA+WZxeyAFL5JxcdGUu35FiVZmEffMyThwqU+G/vMSZsv aB X-Received: by 2002:a5d:608a:: with SMTP id w10mr36053912wrt.596.1641197071197; 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: linux-kernel@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