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 X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 82A55C3A5A0 for ; Mon, 19 Aug 2019 15:41:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5E2C1206BB for ; Mon, 19 Aug 2019 15:41:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727483AbfHSPlX (ORCPT ); Mon, 19 Aug 2019 11:41:23 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46494 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726553AbfHSPlX (ORCPT ); Mon, 19 Aug 2019 11:41:23 -0400 Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 966D111A13 for ; Mon, 19 Aug 2019 15:41:22 +0000 (UTC) Received: by mail-wr1-f71.google.com with SMTP id h3so5432186wrw.7 for ; Mon, 19 Aug 2019 08:41:22 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:openpgp:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=+2urDoQQb7wRsJCEAVPq+MCyS4Og2E5SQlROH1kJHAg=; b=blz9RNQgrerI6wZ24mCKd5h5OXU+laQTDCWK3gEANRr8o7YB6tl6cRtotzyj1USNnA RnH2zG8lTHuzCABLAtjAbDdbIU0KdRYsvirY3Uzx3Qkbj0iVKn2aJ7LIgpad+mPqSTIK bboF21nI5ptMrcC2KBQq6zVdFfkUW8Z6ET3QoBVNkrh7Yvt7/ANK5e7hQlyKI6XfvKwM WnS8AtnLUPIWr8RJBrghCbox1Zs/KaDBvpAKJZGfui2TyztJQFFaizKOWkitGX7zVua/ 5b/JjqZezJ3gNZvngvLiYrsWRW0t5F2AJ98zWKSqm0QbtQUwUuN0VIrfXIkWXN8vm1CE tbtQ== X-Gm-Message-State: APjAAAVj3MWX6j/HSp8ajwrmV1mYSi4p4hw7KDlPfYqpJ59qlo0Cfnk7 XJpse21CoYF3wOjpN6R/Sw7U9V2IBn8cvb5bShhbHHwtMk/24f+oKbnHW5kltL6kNQzxti9sKKr frB7DHL9wsXUsCuBOFyhgZ6Ix X-Received: by 2002:a7b:cbd3:: with SMTP id n19mr16884020wmi.112.1566229281277; Mon, 19 Aug 2019 08:41:21 -0700 (PDT) X-Google-Smtp-Source: APXvYqxXrtziC4pwiiWc6YsHWf6HCM+IBZ85DkcjdCrraoIwl47e8rYcjXkU8W3v5tXs0TOBf6XFbA== X-Received: by 2002:a7b:cbd3:: with SMTP id n19mr16883981wmi.112.1566229280992; Mon, 19 Aug 2019 08:41:20 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:8033:56b6:f047:ba4f? ([2001:b07:6468:f312:8033:56b6:f047:ba4f]) by smtp.gmail.com with ESMTPSA id e15sm7249653wrj.74.2019.08.19.08.41.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 19 Aug 2019 08:41:20 -0700 (PDT) Subject: Re: [PATCH 2/2] KVM: x86: always expose VIRT_SSBD to guests To: Eduardo Habkost Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Konrad Rzeszutek Wilk References: <1565854883-27019-1-git-send-email-pbonzini@redhat.com> <1565854883-27019-3-git-send-email-pbonzini@redhat.com> <20190815171454.GV3908@habkost.net> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: Date: Mon, 19 Aug 2019 17:41:24 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190815171454.GV3908@habkost.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 15/08/19 19:14, Eduardo Habkost wrote: > On Thu, Aug 15, 2019 at 09:41:23AM +0200, Paolo Bonzini wrote: >> Even though it is preferrable to use SPEC_CTRL (represented by >> X86_FEATURE_AMD_SSBD) instead of VIRT_SPEC, VIRT_SPEC is always >> supported anyway because otherwise it would be impossible to >> migrate from old to new CPUs. Make this apparent in the >> result of KVM_GET_SUPPORTED_CPUID as well. >> >> Cc: Konrad Rzeszutek Wilk >> Reported-by: Eduardo Habkost >> Signed-off-by: Paolo Bonzini >> --- >> arch/x86/kvm/cpuid.c | 10 ++++++---- >> 1 file changed, 6 insertions(+), 4 deletions(-) >> >> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c >> index 145ec050d45d..5865bc73bbb5 100644 >> --- a/arch/x86/kvm/cpuid.c >> +++ b/arch/x86/kvm/cpuid.c >> @@ -747,11 +747,13 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function, >> entry->ebx &= kvm_cpuid_8000_0008_ebx_x86_features; >> cpuid_mask(&entry->ebx, CPUID_8000_0008_EBX); >> /* >> - * The preference is to use SPEC CTRL MSR instead of the >> - * VIRT_SPEC MSR. >> + * VIRT_SPEC is only implemented for AMD processors, >> + * but the host could set AMD_SSBD if it wanted even >> + * for Intel processors. >> */ >> - if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) && >> - !boot_cpu_has(X86_FEATURE_AMD_SSBD)) >> + if ((boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) || >> + boot_cpu_has(X86_FEATURE_AMD_SSBD)) && >> + boot_cpu_has(X86_FEATURE_SVM)) > > Would it be desirable to move this code to > svm_set_supported_cpuid(), or is there a reason for keeping this > in cpuid.c? Yes, of course. Forgot about it. Paolo