From patchwork Wed May 12 07:54:42 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joerg Roedel X-Patchwork-Id: 12252963 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 EDF80C43603 for ; Wed, 12 May 2021 07:55:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C0699613BA for ; Wed, 12 May 2021 07:55:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230364AbhELH40 (ORCPT ); Wed, 12 May 2021 03:56:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57774 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230272AbhELH4U (ORCPT ); Wed, 12 May 2021 03:56:20 -0400 Received: from theia.8bytes.org (8bytes.org [IPv6:2a01:238:4383:600:38bc:a715:4b6d:a889]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8A3EDC06175F; Wed, 12 May 2021 00:55:12 -0700 (PDT) Received: from cap.home.8bytes.org (p549ad305.dip0.t-ipconnect.de [84.154.211.5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by theia.8bytes.org (Postfix) with ESMTPSA id 14ABF3E6; Wed, 12 May 2021 09:55:09 +0200 (CEST) From: Joerg Roedel To: x86@kernel.org, Hyunwook Baek Cc: Joerg Roedel , Joerg Roedel , stable@vger.kernel.org, hpa@zytor.com, Andy Lutomirski , Dave Hansen , Peter Zijlstra , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , David Rientjes , Cfir Cohen , Erdem Aktas , Masami Hiramatsu , Mike Stunes , Sean Christopherson , Martin Radev , Arvind Sankar , linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: [PATCH 3/6] x86/sev-es: Use __put_user()/__get_user Date: Wed, 12 May 2021 09:54:42 +0200 Message-Id: <20210512075445.18935-4-joro@8bytes.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210512075445.18935-1-joro@8bytes.org> References: <20210512075445.18935-1-joro@8bytes.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Joerg Roedel The put_user() and get_user() functions do checks on the address which is passed to them. They check whether the address is actually a user-space address and whether its fine to access it. They also call might_fault() to indicate that they could fault and possibly sleep. All of these checks are neither wanted nor required in the #VC exception handler, which can be invoked from almost any context and also for MMIO instructions from kernel space on kernel memory. All the #VC handler wants to know is whether a fault happened when the access was tried. This is provided by __put_user()/__get_user(), which just do the access no matter what. Fixes: f980f9c31a92 ("x86/sev-es: Compile early handler code into kernel image") Cc: stable@vger.kernel.org # v5.10+ Signed-off-by: Joerg Roedel --- arch/x86/kernel/sev.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 6530a844eb61..110b39345b40 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -342,22 +342,22 @@ static enum es_result vc_write_mem(struct es_em_ctxt *ctxt, switch (size) { case 1: memcpy(&d1, buf, 1); - if (put_user(d1, target)) + if (__put_user(d1, target)) goto fault; break; case 2: memcpy(&d2, buf, 2); - if (put_user(d2, target)) + if (__put_user(d2, target)) goto fault; break; case 4: memcpy(&d4, buf, 4); - if (put_user(d4, target)) + if (__put_user(d4, target)) goto fault; break; case 8: memcpy(&d8, buf, 8); - if (put_user(d8, target)) + if (__put_user(d8, target)) goto fault; break; default: @@ -396,22 +396,22 @@ static enum es_result vc_read_mem(struct es_em_ctxt *ctxt, switch (size) { case 1: - if (get_user(d1, s)) + if (__get_user(d1, s)) goto fault; memcpy(buf, &d1, 1); break; case 2: - if (get_user(d2, s)) + if (__get_user(d2, s)) goto fault; memcpy(buf, &d2, 2); break; case 4: - if (get_user(d4, s)) + if (__get_user(d4, s)) goto fault; memcpy(buf, &d4, 4); break; case 8: - if (get_user(d8, s)) + if (__get_user(d8, s)) goto fault; memcpy(buf, &d8, 8); break;