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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 6CF81C433E6 for ; Wed, 22 Jul 2020 16:22:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3D3F72065F for ; Wed, 22 Jul 2020 16:22:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595434923; bh=NnybZoElq3+0KYwoEu4w7pBb4jnYvQOexyS5ysvraSE=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=To2kqfr5ih+bAJqTEDWxPIwFiBEe0/MTG5rjl8g+6+ywzgCydeEQEpKvTC3MQBEQF ncFoi/0BiL9LQC2DUGzr7owTa8IX1GuPQ6S+dQ/PQ9/+XWoHzjO/aqjEXFqQVp+K5d RAebMlOZPq4xM91MBIiV1mtoXY24GSmWrFhqBFSk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728612AbgGVQWC (ORCPT ); Wed, 22 Jul 2020 12:22:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:46344 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728059AbgGVQV5 (ORCPT ); Wed, 22 Jul 2020 12:21:57 -0400 Received: from mail-wr1-f45.google.com (mail-wr1-f45.google.com [209.85.221.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D6F4722CA0 for ; Wed, 22 Jul 2020 16:21:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595434917; bh=NnybZoElq3+0KYwoEu4w7pBb4jnYvQOexyS5ysvraSE=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=UcMcUqZGs3A/zHint+yQtia7Uf3Fb8yRh4OyYW73633eFDF8vcz9eD7uDnKQ/c0cu yoA7jR0qN1gN5YgaAVpozWehWHO7y/XScv8pB/dupzQgn5vR4+tU+XPdcM9ijeUk8u 8oa5kAzlA1/+LXQc6uLgnZdv5H6c3AhKs2JE2T38= Received: by mail-wr1-f45.google.com with SMTP id f1so1941474wro.2 for ; Wed, 22 Jul 2020 09:21:56 -0700 (PDT) X-Gm-Message-State: AOAM531lBQD1Eqmr7Qsw9FnCi+k4atwk1ECeCPCi2swO/h5wiu2iawSB 0UB5nlAytqLF5ToSek+mo1Eqe0owscV9wl8mhcxV7w== X-Google-Smtp-Source: ABdhPJyEetM5mfaR+krsbN1VbThAmtrGRoGcIADpoq0lN9rBpz6OtbXdH4MYYDkEz8tY7NVo/wEe+Jv+iOx79Efg25I= X-Received: by 2002:adf:e482:: with SMTP id i2mr296828wrm.75.1595434915303; Wed, 22 Jul 2020 09:21:55 -0700 (PDT) MIME-Version: 1.0 References: <20200717072056.73134-1-ira.weiny@intel.com> <20200717072056.73134-18-ira.weiny@intel.com> In-Reply-To: <20200717072056.73134-18-ira.weiny@intel.com> From: Andy Lutomirski Date: Wed, 22 Jul 2020 09:21:43 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH RFC V2 17/17] x86/entry: Preserve PKRS MSR across exceptions To: Weiny Ira Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Andy Lutomirski , Peter Zijlstra , Dave Hansen , X86 ML , Dan Williams , Vishal Verma , Andrew Morton , Fenghua Yu , "open list:DOCUMENTATION" , LKML , linux-nvdimm , Linux FS Devel , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" Content-Type: text/plain; charset="UTF-8" Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Fri, Jul 17, 2020 at 12:21 AM wrote: > > From: Ira Weiny > > The PKRS MSR is not managed by XSAVE. It is already preserved through a > context switch but this support leaves exception handling code open to > memory accesses which the interrupted process has allowed. > > Close this hole by preserve the current task's PKRS MSR, reset the PKRS > MSR value on exception entry, and then restore the state on exception > exit. Should this live in pt_regs? --Andy