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=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 A536CC433B4 for ; Wed, 31 Mar 2021 21:53:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5CC0661002 for ; Wed, 31 Mar 2021 21:53:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232290AbhCaVx2 (ORCPT ); Wed, 31 Mar 2021 17:53:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57472 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231676AbhCaVxT (ORCPT ); Wed, 31 Mar 2021 17:53:19 -0400 Received: from mail-pg1-x52d.google.com (mail-pg1-x52d.google.com [IPv6:2607:f8b0:4864:20::52d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8111DC061574 for ; Wed, 31 Mar 2021 14:53:18 -0700 (PDT) Received: by mail-pg1-x52d.google.com with SMTP id w10so249202pgh.5 for ; Wed, 31 Mar 2021 14:53:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=MM0j2oe36X//rQQ8+GyI9vMxc0vf6Nwq2VgkiW4HgEw=; b=eiEMv4/PuzRRpwJGs4ojsw2qXKVA+nsWHdR/jJo8hrb977VXco2X0B5pJTRZngZvI3 mj+E2o1JLGDQ7ePxR1DzidIkcOWf6HpuTaTbOkvCxVanOg7kssWTRzyJ+mq8+JF6R8bS a7doki5tC3wTAMlO3vi4fNjPWeRN5Eb45UOI+quwVBHfrS4VnPKxKKON9nTfFXG871c5 GQFkXfw/PFnAeCso4esXRCMAxBNw1toz0booDEaSZ/55+91axgNUd47cTjH5O6+t45aN IwpZC48V92xTnQiiaS8fZpgqmrdwA6lqAgUOE1pm5rBzBFfMZR2Xuz2aZCoRAseLOgiD 5Jvw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=MM0j2oe36X//rQQ8+GyI9vMxc0vf6Nwq2VgkiW4HgEw=; b=QS9gjFLva/4kkhpxq5L/rNjTYBwKIRdo76cWT3DuT7JamWWcAA0SITfkjPYr+3/T0s xGlv7JE7i45DG4HhsfQYKzaBxxo6qtK3lSxfFm7N0s8wJN8deRFIolmL4HUo4yHU/NyS buZwBO5SG9o0zsaqY9zBHTHSjvsoxowI8BjzlP8WYCp/XJlHUBqgCDLjQOsU34diib+A Hc8yFABTzFJdJG3jvVIg3q9hHOP8AbkkxoT9MmMK0IyN0t5FhBlcKqaIqeeS3vd8aUcz JHRgGL/2/nVK2vuMUD+UI1wpZNU7EXw5iYCZaMIK2F48K9ngx6lavVV7iDqjeeewOiA0 GHFw== X-Gm-Message-State: AOAM532LNnPc6zReE82iq2O3lS1HWi00pBhP8ICLK0l8pH1kWE9AhXBu TAxItWylE61qGQ/r86EumzzeGQ== X-Google-Smtp-Source: ABdhPJzxk3OvWmDbPosHgkRyAsP6nvxaf+fnOjHVCqb5cNwnBuDUp1zakhvQzQOhTHLpnCqXFcMjJQ== X-Received: by 2002:a62:7f45:0:b029:205:9617:a819 with SMTP id a66-20020a627f450000b02902059617a819mr4681004pfd.17.1617227598227; Wed, 31 Mar 2021 14:53:18 -0700 (PDT) Received: from google.com (240.111.247.35.bc.googleusercontent.com. [35.247.111.240]) by smtp.gmail.com with ESMTPSA id s22sm3172807pfe.150.2021.03.31.14.53.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 31 Mar 2021 14:53:17 -0700 (PDT) Date: Wed, 31 Mar 2021 21:53:14 +0000 From: Sean Christopherson To: Kuppuswamy Sathyanarayanan Cc: Peter Zijlstra , Andy Lutomirski , Dave Hansen , Andi Kleen , Kirill Shutemov , Kuppuswamy Sathyanarayanan , Dan Williams , Raj Ashok , linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 1/1] x86/tdx: Handle MWAIT, MONITOR and WBINVD Message-ID: References: <2FE32855-EA5D-44E4-AACC-25E9B1476547@amacapital.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 31, 2021, Kuppuswamy Sathyanarayanan wrote: > Changes since v3: > * WARN user if SEAM does not disable MONITOR/MWAIT instruction. Why bother? There are a whole pile of features that are dictated by the TDX module spec. MONITOR/MWAIT is about as uninteresting as it gets, e.g. absolute worst case scenario is the guest kernel crashes, whereas a lot of spec violations would compromise the security of the guest. > + case EXIT_REASON_MONITOR_INSTRUCTION: > + case EXIT_REASON_MWAIT_INSTRUCTION: > + /* > + * MWAIT/MONITOR features are disabled by TDX Module (SEAM) > + * and also re-suppressed in kernel by clearing > + * X86_FEATURE_MWAIT CPU feature flag in tdx_early_init(). So > + * if TD guest still executes MWAIT/MONITOR instruction with > + * above suppression, it needs user attention. > + */ > + WARN(1, "TD Guest used unsupported MWAIT/MONITOR instruction\n"); Why not just WARN_ONCE and call it good? > + break; > default: > pr_warn("Unexpected #VE: %d\n", ve->exit_reason); > return -EFAULT; > -- > 2.25.1 >