From patchwork Fri Mar 19 12:38:01 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vitaly Kuznetsov X-Patchwork-Id: 1455842 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=g0P+6M73; dkim-atps=neutral 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 ozlabs.org (Postfix) with ESMTPS id 4F23Nk4CdRz9sRf for ; Fri, 19 Mar 2021 23:39:02 +1100 (AEDT) Received: from localhost ([::1]:39644 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lNEP6-0005Ya-Ks for incoming@patchwork.ozlabs.org; Fri, 19 Mar 2021 08:39:00 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:50860) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lNEON-0005Xb-OH for qemu-devel@nongnu.org; Fri, 19 Mar 2021 08:38:16 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:43853) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lNEOJ-0000UC-Bg for qemu-devel@nongnu.org; Fri, 19 Mar 2021 08:38:15 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616157487; 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; bh=WtN2veN2OXQg3V1xJGwr9EPz6jYHWLQCOjn4GhvTTJY=; b=g0P+6M73ScB4m9P2uiKSEHT30+cv0fwfPNribo+qGUkZfu7TWxujSQmLfzFXWoiV3uld5i XNyR6EiVIV0g0siVA2FoHQI/vMKb/tWzwK+AitMCGWvWMVRqEkrM9QejC/7K2sQDXsEA6+ pLjThZUNNwtcodQZ+hOwQappzvoKA/E= 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-434-TxOqslWqOFWtEcR-veJg6Q-1; Fri, 19 Mar 2021 08:38:06 -0400 X-MC-Unique: TxOqslWqOFWtEcR-veJg6Q-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 255151926DA0; Fri, 19 Mar 2021 12:38:05 +0000 (UTC) Received: from vitty.brq.redhat.com (unknown [10.40.195.142]) by smtp.corp.redhat.com (Postfix) with ESMTP id 443A819C79; Fri, 19 Mar 2021 12:38:03 +0000 (UTC) From: Vitaly Kuznetsov To: qemu-devel@nongnu.org Subject: [PATCH v2] i386: Make migration fail when Hyper-V reenlightenment was enabled but 'user_tsc_khz' is unset Date: Fri, 19 Mar 2021 13:38:01 +0100 Message-Id: <20210319123801.1111090-1-vkuznets@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=vkuznets@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=63.128.21.124; envelope-from=vkuznets@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.251, 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: Paolo Bonzini , Marcelo Tosatti , Richard Henderson , Eduardo Habkost , "Dr . David Alan Gilbert" Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" KVM doesn't fully support Hyper-V reenlightenment notifications on migration. In particular, it doesn't support emulating TSC frequency of the source host by trapping all TSC accesses so unless TSC scaling is supported on the destination host and KVM_SET_TSC_KHZ succeeds, it is unsafe to proceed with migration. KVM_SET_TSC_KHZ is called from two sites: kvm_arch_init_vcpu() and kvm_arch_put_registers(). The later (intentionally) doesn't propagate errors allowing migrations to succeed even when TSC scaling is not supported on the destination. This doesn't suit 're-enlightenment' use-case as we have to guarantee that TSC frequency stays constant. Require 'tsc-frequency=' command line option to be specified for successful migration when re-enlightenment was enabled by the guest. Signed-off-by: Vitaly Kuznetsov --- This patch is a successor of "[PATCH 3/3] i386: Make sure kvm_arch_set_tsc_khz() succeeds on migration when 'hv-reenlightenment' was exposed" taking a different approach suggested by Paolo. --- docs/hyperv.txt | 5 +++++ target/i386/kvm/hyperv-proto.h | 1 + target/i386/machine.c | 20 ++++++++++++++++++++ 3 files changed, 26 insertions(+) diff --git a/docs/hyperv.txt b/docs/hyperv.txt index 5df00da54fc4..e53c581f4586 100644 --- a/docs/hyperv.txt +++ b/docs/hyperv.txt @@ -160,6 +160,11 @@ the hypervisor) until it is ready to switch to the new one. This, in conjunction with hv-frequencies, allows Hyper-V on KVM to pass stable clocksource (Reference TSC page) to its own guests. +Note, KVM doesn't fully support re-enlightenment notifications and doesn't +emulate TSC accesses after migration so 'tsc-frequency=' CPU option also has to +be specified to make migration succeed. The destination host has to either have +the same TSC frequency or support TSC scaling CPU feature. + Recommended: hv-frequencies 3.16. hv-evmcs diff --git a/target/i386/kvm/hyperv-proto.h b/target/i386/kvm/hyperv-proto.h index 056a305be38c..e30d64b4ade4 100644 --- a/target/i386/kvm/hyperv-proto.h +++ b/target/i386/kvm/hyperv-proto.h @@ -139,6 +139,7 @@ * Reenlightenment notification MSRs */ #define HV_X64_MSR_REENLIGHTENMENT_CONTROL 0x40000106 +#define HV_REENLIGHTENMENT_ENABLE_BIT (1u << 16) #define HV_X64_MSR_TSC_EMULATION_CONTROL 0x40000107 #define HV_X64_MSR_TSC_EMULATION_STATUS 0x40000108 diff --git a/target/i386/machine.c b/target/i386/machine.c index 7259fe6868c6..137604ddb898 100644 --- a/target/i386/machine.c +++ b/target/i386/machine.c @@ -883,11 +883,31 @@ static bool hyperv_reenlightenment_enable_needed(void *opaque) env->msr_hv_tsc_emulation_status != 0; } +static int hyperv_reenlightenment_post_load(void *opaque, int version_id) +{ + X86CPU *cpu = opaque; + CPUX86State *env = &cpu->env; + + /* + * KVM doesn't fully support re-enlightenment notifications so we need to + * make sure TSC frequency doesn't change upon migration. + */ + if ((env->msr_hv_reenlightenment_control & HV_REENLIGHTENMENT_ENABLE_BIT) && + !env->user_tsc_khz) { + error_report("Guest enabled re-enlightenment notifications, " + "'tsc-frequency=' has to be specified"); + return -EINVAL; + } + + return 0; +} + static const VMStateDescription vmstate_msr_hyperv_reenlightenment = { .name = "cpu/msr_hyperv_reenlightenment", .version_id = 1, .minimum_version_id = 1, .needed = hyperv_reenlightenment_enable_needed, + .post_load = hyperv_reenlightenment_post_load, .fields = (VMStateField[]) { VMSTATE_UINT64(env.msr_hv_reenlightenment_control, X86CPU), VMSTATE_UINT64(env.msr_hv_tsc_emulation_control, X86CPU),