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[23.128.96.18]) by mx.google.com with ESMTP id x21si1202568pgk.509.2021.04.21.17.20.04; Wed, 21 Apr 2021 17:20:16 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=desiato.20200630 header.b=bwTX+Poy; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244230AbhDUQFV (ORCPT + 99 others); Wed, 21 Apr 2021 12:05:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50762 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244225AbhDUQFV (ORCPT ); Wed, 21 Apr 2021 12:05:21 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 48613C06174A for ; Wed, 21 Apr 2021 09:04:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Transfer-Encoding:Content-Type :In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Subject: Sender:Reply-To:Content-ID:Content-Description; bh=XHthP/flvcnD9WPMwE3WBFicv5jL7de75V4TawaXxpA=; b=bwTX+Poy8a5vED5MWK8h65DCcg OZxc3/wzzlU06PUZoT0RTHujCWYgG3RLRyokIHYF2+Ke0EZMlwUr/iXT9YRdmM0woeySHS5Tt18wv vhqosPvU68sjgpRIr3yRyR/cwYryUBIVFwZSfouSgdpZmD19444ppxKiBUNSFZhyjgf6Q6UWc+Drx rNBDBiu4ly9shovOjpa1VSdnPXhFGs2ZsbbCzZfTmyq70AlzpVateynSeHqWaRwyoM9xFOp5XK1hR P7dvV62tdzuwn0pFa+Zxvrry+/3k7r5boXNeLm6cjVDfe3KWn+zMvq4xHlghgPvgO7Ou3Vk4a/sA3 QES3XOKA==; Received: from [2601:1c0:6280:3f0:d7c4:8ab4:31d7:f0ba] by desiato.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lZFL8-00EioC-Fl; Wed, 21 Apr 2021 16:04:34 +0000 Subject: Re: [PATCH 4/4] x86/speculation: Add PSF mitigation kernel parameters To: Ramakrishna Saripalli , linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, Jonathan Corbet Cc: bsd@redhat.com References: <20210421090117.22315-1-rsaripal@amd.com> <20210421090117.22315-5-rsaripal@amd.com> From: Randy Dunlap Message-ID: <4c688fc7-67df-3187-54b2-bf20e510fb39@infradead.org> Date: Wed, 21 Apr 2021 09:04:30 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <20210421090117.22315-5-rsaripal@amd.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 4/21/21 2:01 AM, Ramakrishna Saripalli wrote: > From: Ramakrishna Saripalli > > PSF mitigation introduces a new kernel parameter called > predict_store_fwd. > > Signed-off-by: Ramakrishna Saripalli > --- > Documentation/admin-guide/kernel-parameters.txt | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 04545725f187..58f6bd02385b 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -3940,6 +3940,11 @@ > Format: {"off"} > Disable Hardware Transactional Memory > > + predict_store_fwd [X86] This option controls PSF mitigation > + off - Turns on PSF mitigation. > + on - Turns off PSF mitigation. > + default : on. This should be formatted more like: + predict_store_fwd= [X86] This option controls PSF mitigation + off - Turns on PSF mitigation. + on - Turns off PSF mitigation. + default: on. But why does "off" turn it on and "on" turn it off? > + > preempt= [KNL] > Select preemption mode if you have CONFIG_PREEMPT_DYNAMIC > none - Limited to cond_resched() calls > thanks. -- ~Randy