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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 84D6BC433B4 for ; Fri, 30 Apr 2021 19:57:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 435D96147F for ; Fri, 30 Apr 2021 19:57:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234182AbhD3T57 (ORCPT ); Fri, 30 Apr 2021 15:57:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35232 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234071AbhD3T5t (ORCPT ); Fri, 30 Apr 2021 15:57:49 -0400 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF0A1C06174A for ; Fri, 30 Apr 2021 12:57:00 -0700 (PDT) Received: from zn.tnic (p200300ec2f0c5700c52031cc761b260f.dip0.t-ipconnect.de [IPv6:2003:ec:2f0c:5700:c520:31cc:761b:260f]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 836C81EC02E6; Fri, 30 Apr 2021 21:56:58 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1619812618; 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:in-reply-to:in-reply-to: references:references; bh=5FxCqAP5C1yOwn+gHliLIDnLy1eAr9ZCmwbDPrcWXuE=; b=rLOVoONOjx7G+tt1vqFbq6KkQJQbGzf6G3em5qSdzcj0NzQqQnC0+kd/F7iYZIrh1ni1PH ROkmTLWJvRTSEatuvzLksGGqt79GZo3sJ+jR0kxAnRt/AzO8ZLoAhkEq6eAMgLYQks6J4M 3T4PyC7Xvfh0Yv+1cetfHTpJGmwtL5c= Date: Fri, 30 Apr 2021 21:56:57 +0200 From: Borislav Petkov To: Reiji Watanabe Cc: Ramakrishna Saripalli , linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, Jonathan Corbet , bsd@redhat.com Subject: Re: [PATCH v4 1/1] x86/cpufeatures: Implement Predictive Store Forwarding control. Message-ID: References: <20210430131733.192414-1-rsaripal@amd.com> <20210430131733.192414-2-rsaripal@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 30, 2021 at 12:42:46PM -0700, Reiji Watanabe wrote: > Then, it would be a problem if its guests want to use PSFD looking at > x86_virt_spec_ctrl(). Well, will they want to do that? If so, why? Use case? We decided to do this lite version to give people the opportunity to evaluate whether there's a need to make full-blown mitigation-like, per-thread thing like the rest of the mitigations in bugs.c or leave it to be a chicken-bit thing. So do you have any particular use case in mind or are you simply poking holes in this? -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette