From patchwork Wed Jun 24 10:50:44 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 279579 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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS autolearn=ham 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 28286C433E0 for ; Wed, 24 Jun 2020 11:00:24 +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 E0D442084D for ; Wed, 24 Jun 2020 11:00:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="EDnl2vMV" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E0D442084D 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]:60230 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jo38h-0002X9-4S for qemu-devel@archiver.kernel.org; Wed, 24 Jun 2020 07:00:23 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56796) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jo2zz-0001Z1-MX for qemu-devel@nongnu.org; Wed, 24 Jun 2020 06:51:23 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:51762 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jo2zx-0001QC-2V for qemu-devel@nongnu.org; Wed, 24 Jun 2020 06:51:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1592995880; 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=G0fxQjUvS31mvtxaUp0D7yZJbxAdTCXA9Iw4PMRAuPo=; b=EDnl2vMVCKyfVf/U++8kVfilQRlao1fGTiP001k+fC7umQxqfDOSwZxM6aP8OtvGB1TBzL hvxc3j54ez1jFGU67vfwe5qfKyVgRI7FFzsgzUq67IplUVfa4VC1yB0meRXch7q0eBhgSK 0azxGTqoyJT5iIhOReaVhYsEjLs4CK8= 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-248-2g3qXzjPNLOJkyqw0rn3lQ-1; Wed, 24 Jun 2020 06:51:18 -0400 X-MC-Unique: 2g3qXzjPNLOJkyqw0rn3lQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D8434107ACCA for ; Wed, 24 Jun 2020 10:51:17 +0000 (UTC) Received: from virtlab511.virt.lab.eng.bos.redhat.com (virtlab511.virt.lab.eng.bos.redhat.com [10.19.152.198]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6B28961981; Wed, 24 Jun 2020 10:51:17 +0000 (UTC) From: Paolo Bonzini To: qemu-devel@nongnu.org Subject: [PULL 27/31] kvm: i386: allow TSC to differ by NTP correction bounds without TSC scaling Date: Wed, 24 Jun 2020 06:50:44 -0400 Message-Id: <20200624105048.375353-27-pbonzini@redhat.com> In-Reply-To: <20200624104917.375143-1-pbonzini@redhat.com> References: <20200624104917.375143-1-pbonzini@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=205.139.110.120; envelope-from=pbonzini@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/24 03:27:53 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN 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: Marcelo Tosatti Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Marcelo Tosatti The Linux TSC calibration procedure is subject to small variations (its common to see +-1 kHz difference between reboots on a given CPU, for example). So migrating a guest between two hosts with identical processor can fail, in case of a small variation in calibrated TSC between them. Allow a conservative 250ppm error between host TSC and VM TSC frequencies, rather than requiring an exact match. NTP daemon in the guest can correct this difference. Also change migration to accept this bound. KVM_SET_TSC_KHZ depends on a kernel interface change. Without this change, the behaviour remains the same: in case of a different frequency between host and VM, KVM_SET_TSC_KHZ will fail and QEMU will exit. Signed-off-by: Marcelo Tosatti Message-Id: <20200616165805.GA324612@fuller.cnet> Signed-off-by: Paolo Bonzini --- target/i386/kvm.c | 46 +++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 41 insertions(+), 5 deletions(-) diff --git a/target/i386/kvm.c b/target/i386/kvm.c index b3c13cb898..6adbff3d74 100644 --- a/target/i386/kvm.c +++ b/target/i386/kvm.c @@ -740,26 +740,62 @@ static bool hyperv_enabled(X86CPU *cpu) cpu->hyperv_features || cpu->hyperv_passthrough); } +/* + * Check whether target_freq is within conservative + * ntp correctable bounds (250ppm) of freq + */ +static inline bool freq_within_bounds(int freq, int target_freq) +{ + int max_freq = freq + (freq * 250 / 1000000); + int min_freq = freq - (freq * 250 / 1000000); + + if (target_freq >= min_freq && target_freq <= max_freq) { + return true; + } + + return false; +} + static int kvm_arch_set_tsc_khz(CPUState *cs) { X86CPU *cpu = X86_CPU(cs); CPUX86State *env = &cpu->env; - int r; + int r, cur_freq; + bool set_ioctl = false; if (!env->tsc_khz) { return 0; } - r = kvm_check_extension(cs->kvm_state, KVM_CAP_TSC_CONTROL) ? + cur_freq = kvm_check_extension(cs->kvm_state, KVM_CAP_GET_TSC_KHZ) ? + kvm_vcpu_ioctl(cs, KVM_GET_TSC_KHZ) : -ENOTSUP; + + /* + * If TSC scaling is supported, attempt to set TSC frequency. + */ + if (kvm_check_extension(cs->kvm_state, KVM_CAP_TSC_CONTROL)) { + set_ioctl = true; + } + + /* + * If desired TSC frequency is within bounds of NTP correction, + * attempt to set TSC frequency. + */ + if (cur_freq != -ENOTSUP && freq_within_bounds(cur_freq, env->tsc_khz)) { + set_ioctl = true; + } + + r = set_ioctl ? kvm_vcpu_ioctl(cs, KVM_SET_TSC_KHZ, env->tsc_khz) : -ENOTSUP; + if (r < 0) { /* When KVM_SET_TSC_KHZ fails, it's an error only if the current * TSC frequency doesn't match the one we want. */ - int cur_freq = kvm_check_extension(cs->kvm_state, KVM_CAP_GET_TSC_KHZ) ? - kvm_vcpu_ioctl(cs, KVM_GET_TSC_KHZ) : - -ENOTSUP; + cur_freq = kvm_check_extension(cs->kvm_state, KVM_CAP_GET_TSC_KHZ) ? + kvm_vcpu_ioctl(cs, KVM_GET_TSC_KHZ) : + -ENOTSUP; if (cur_freq <= 0 || cur_freq != env->tsc_khz) { warn_report("TSC frequency mismatch between " "VM (%" PRId64 " kHz) and host (%d kHz), "