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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1FE85C433EF for ; Thu, 7 Jul 2022 22:47:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236565AbiGGWrJ (ORCPT ); Thu, 7 Jul 2022 18:47:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42358 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230294AbiGGWrI (ORCPT ); Thu, 7 Jul 2022 18:47:08 -0400 Received: from mail-pf1-x435.google.com (mail-pf1-x435.google.com [IPv6:2607:f8b0:4864:20::435]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C57EC5073C for ; Thu, 7 Jul 2022 15:47:06 -0700 (PDT) Received: by mail-pf1-x435.google.com with SMTP id b9so5995976pfp.10 for ; Thu, 07 Jul 2022 15:47:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=k+m9xndrEVogn4UNNIC2n16CcYTa0z3ZXhM1HLDkBjM=; b=TydelTAwAa4eGTpazSqNuIiD7itOzqcNBA+U88a230OX9KGADCgmA4zPjqlydWgPU8 Eqqh5cvCKl+XqdCEfl4R7z2mtJjy3jHOCh0VS9H610rlMdRluVNzGmsz0aHR4w6dUrbD gsn08raGW6vup7/kAENTSDseBQZnp0iZqE26t3j6Ln6H+vnfW/f61TZ6/voLJxZETDox 4N780WO0xF9pUZAQ3qhYcLRGRWOBayJHjtv8wnVmlCuLMGaf4YKYUWk9aM9lDDp7ZsgB dx+4sLMS0SisSFldoVAzwylKOQVDqa26r4uEDRHdfAv8CPMnOH0HU1MFtOk8LitCwPcI q9jw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=k+m9xndrEVogn4UNNIC2n16CcYTa0z3ZXhM1HLDkBjM=; b=WuIv56cN5WOYNuttKX9nfljgXlfn0E8QD+JwtrmSogQS8zEMZlLOLPxUqIRaCrVGw9 IUYcqrPOUB8dhHydaMaqCsw09SHmhLv1stFXxyhxc70oUx3u+03brp52gxKIA4u+Rold CzK+fRDYh+uq68YMXclKzK9oseW6VjYBluRSKz8ROuMhMrDWs270uG4tx5D+XEeIU2Jk gT5weCYnrqY5HjCFpVpiTjKTqjr/kcUtl4nchkYGpn3IJ6gpg98MREp5CIZlUo+JbfQd wDJ4hkHKTxYhh9FTBvlr7UMutBjyfBV0yUTdt1jsirAovvhrWBfrn1abwdGuHPxFnW7F 6d6w== X-Gm-Message-State: AJIora9yLNp15L+meec/BofD7DAENZIuZRBtE6mqAO3g0fbkJ+C8yCus k0NP+J4/BXsE2CrDrjd1vU2WtV6QjK0ZzA== X-Google-Smtp-Source: AGRyM1tCjKHzVatwgeDBwjMuyukTx03peOGiilV2bNfDEtYojbP0OJirTDnFBtcgnOsduVbet0w7zg== X-Received: by 2002:a63:5346:0:b0:412:9544:1ff2 with SMTP id t6-20020a635346000000b0041295441ff2mr360152pgl.504.1657234026238; Thu, 07 Jul 2022 15:47:06 -0700 (PDT) Received: from google.com (123.65.230.35.bc.googleusercontent.com. [35.230.65.123]) by smtp.gmail.com with ESMTPSA id x9-20020a056a00188900b0050dc762818csm27687814pfh.102.2022.07.07.15.47.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 Jul 2022 15:47:05 -0700 (PDT) Date: Thu, 7 Jul 2022 22:47:01 +0000 From: Sean Christopherson To: Jim Mattson Cc: kvm@vger.kernel.org, pbonzini@redhat.com Subject: Re: [PATCH v3] KVM: VMX: Avoid a JMP over the RSB-stuffing sequence Message-ID: References: <20220707212049.3833395-1-jmattson@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220707212049.3833395-1-jmattson@google.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Jul 07, 2022, Jim Mattson wrote: > RSB-stuffing after VM-exit is only needed for legacy CPUs without > eIBRS. Instead of jumping over the RSB-stuffing sequence on modern > CPUs, just return immediately. > > Note that CPUs that are subject to SpectreRSB attacks need > RSB-stuffing on VM-exit whether or not RETPOLINE is in use as a > SpectreBTB mitigation. However, I am leaving the existing mitigation > strategy alone. > > Signed-off-by: Jim Mattson > --- Reviewed-by: Sean Christopherson