Received: by 2002:a25:e74b:0:0:0:0:0 with SMTP id e72csp638462ybh; Wed, 22 Jul 2020 09:22:38 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyvbMbtvTchx3NB4V9rzOdzwslgzZOREU2hR7WSE+eP+s+nKRfXQIwHPDRgFINBdA7QWAV7 X-Received: by 2002:a17:906:950c:: with SMTP id u12mr315003ejx.37.1595434958420; Wed, 22 Jul 2020 09:22:38 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1595434958; cv=none; d=google.com; s=arc-20160816; b=F5HMNYaccfpgCZ0FJY3zlt18K9K+Usd1RZe/p5AEPgUe3zeFQB8vF86A1/lbvmWtkk S6SmM6bYsH8xyxMNwEIDop83TArMSpiFPiHB/1iMKuL2RuLb0LDvi21VXOFTZuy212RY e46B//sqUGbCVwLbpWU/RGbNNOGQMyzAEEnezlBIHc11m0kLor8dKam8o6zWBPisOxYG BJT4SU6IYwI4NIw+oSfZxLz0hhub+q/a+R+8x+yoipG1BL7/jteBhrbNXGtmwGHcIJy1 jZY7nFXpr2qC/zTkBrrLFj3Tug68m3dF9zSeLcRm9lgXmrM8y1+qpP3GGLsDv6mUO+T5 zvaw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:dkim-signature; bh=pU9yoKFQ/x55OlC49BNL4cx2Zsut3SNO+ePeZxlFw80=; b=SEDg/E/9Jkv1Zr5ZE/Es8kBsC40i5B8BY0QzXy2pAoPAWcr7nL7vpizSUty/ov2WmR pEkNWjScHCgYO8TbepUi0SQrV3JLZ1MQsLCff2tlCgFeLREnpkl4OoXHymlCG/Pez9OM s5Y66vhjVp6ygoXRi7eFzfk0FCT/g1azKGqvm5582Ao7aoN7BHHkW/K1dtdvkDrJrnrk P3NZ0lFJg73JvyPy4VxM2oDo3vggQNGIhT/Qp0CgM+1XWyMQfuYI3z4Qm9TS8So65L7x FSpw+LaGazfNobpMIGuDb11YJ8BdZP127sSv0CzeeLdRLYRG+uwi8+brF4IeyYxfAwIM 4I6A== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=UcMcUqZG; 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; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id dp14si379442ejc.609.2020.07.22.09.22.14; Wed, 22 Jul 2020 09:22:38 -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=@kernel.org header.s=default header.b=UcMcUqZG; 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; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730494AbgGVQV6 (ORCPT + 99 others); Wed, 22 Jul 2020 12:21:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:46346 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728612AbgGVQV5 (ORCPT ); Wed, 22 Jul 2020 12:21:57 -0400 Received: from mail-wr1-f52.google.com (mail-wr1-f52.google.com [209.85.221.52]) (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 D56A722C9E 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-f52.google.com with SMTP id f18so2507649wrs.0 for ; Wed, 22 Jul 2020 09:21:56 -0700 (PDT) X-Gm-Message-State: AOAM530GTQAXsTKD97kcWG6T7ZgohBvvG0lZljtspxQN9uKM4FGegVup xDVyKVEJUv9IlKPCMBGYmctVgbqsVdBnplOFAzNxcA== 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-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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