From patchwork Tue Oct 17 18:21:55 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Limonciello, Mario" X-Patchwork-Id: 10012713 X-Patchwork-Delegate: dvhart@infradead.org Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 3D99160211 for ; Tue, 17 Oct 2017 18:25:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3604E289D4 for ; Tue, 17 Oct 2017 18:25:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2A105289D6; Tue, 17 Oct 2017 18:25:22 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D5C94289D4 for ; Tue, 17 Oct 2017 18:25:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758221AbdJQSYL (ORCPT ); Tue, 17 Oct 2017 14:24:11 -0400 Received: from esa7.dell-outbound.iphmx.com ([68.232.153.96]:22130 "EHLO esa7.dell-outbound.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934585AbdJQSWL (ORCPT ); Tue, 17 Oct 2017 14:22:11 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=dell.com; i=@dell.com; q=dns/txt; s=smtpout; t=1508264100; x=1539800100; h=from:to:cc:subject:date:message-id; bh=0OdzjNZPdTJvNPL7qaRXQKlQeFLyKviInxQwze2JB34=; b=pOvrBh/j8++5gwkXMEC+kcSZgeoYT9zr1WW1bUQ4WXXmvQAj7U6L8kCw wTkfm2xynUold4IyKnEBZYYbK0YztbT3Qhz0bTxofMNbi9qth+9/MoAiw TjEFMupu93j7jWppzCr+oPChwpbH4XMp3mdbYUZRGdIhVCGW2/U++pKBm U=; Received: from esa5.dell-outbound2.iphmx.com ([68.232.153.203]) by esa7.dell-outbound.iphmx.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 17 Oct 2017 13:14:57 -0500 Received: from ausxipps306.us.dell.com ([143.166.148.156]) by esa5.dell-outbound2.iphmx.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Oct 2017 00:14:35 +0600 X-LoopCount0: from 10.208.86.39 X-IronPort-AV: E=Sophos;i="5.43,391,1503378000"; d="scan'208";a="161471189" X-DLP: DLP_GlobalPCIDSS From: Mario Limonciello To: dvhart@infradead.org, Andy Shevchenko Cc: LKML , platform-driver-x86@vger.kernel.org, Andy Lutomirski , quasisec@google.com, pali.rohar@gmail.com, rjw@rjwysocki.net, mjg59@google.com, hch@lst.de, Greg KH , Alan Cox , Mario Limonciello Subject: [PATCH v9 11/17] platform/x86: dell-smbios-smm: test for WSMT Date: Tue, 17 Oct 2017 13:21:55 -0500 Message-Id: X-Mailer: git-send-email 2.7.4 In-Reply-To: References: In-Reply-To: References: Sender: platform-driver-x86-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: platform-driver-x86@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP WSMT is as an attestation to the OS that the platform won't modify memory outside of pre-defined areas. If a platform has WSMT enabled in BIOS setup, SMM calls through dcdbas will fail. The only way to access platform data in these instances is through the WMI SMBIOS calling interface. Signed-off-by: Mario Limonciello Reviewed-by: Edward O'Callaghan --- drivers/platform/x86/dell-smbios-smm.c | 33 +++++++++++++++++++++++++++++++++ drivers/platform/x86/dell-smbios.h | 2 ++ 2 files changed, 35 insertions(+) diff --git a/drivers/platform/x86/dell-smbios-smm.c b/drivers/platform/x86/dell-smbios-smm.c index 53eabb14fb48..c2dfe4c5908c 100644 --- a/drivers/platform/x86/dell-smbios-smm.c +++ b/drivers/platform/x86/dell-smbios-smm.c @@ -102,6 +102,31 @@ int dell_smbios_smm_call(struct calling_interface_buffer *input) return 0; } +/* When enabled this indicates that SMM won't work */ +static int test_wsmt_enabled(void) +{ + struct calling_interface_token *token; + + /* if token doesn't exist, SMM will work */ + token = dell_smbios_find_token(WSMT_EN_TOKEN); + if (!token) + return 0; + + /* if token exists, try to access over SMM */ + buffer->class = CLASS_TOKEN_READ; + buffer->select = SELECT_TOKEN_STD; + memset(buffer, 0, sizeof(struct calling_interface_buffer)); + buffer->input[0] = token->location; + dell_smbios_smm_call(buffer); + + /* if lookup failed, we know WSMT was enabled */ + if (buffer->output[0] != 0) + return 1; + + /* query token status if it didn't fail */ + return (buffer->output[1] == token->value); +} + static int __init dell_smbios_smm_init(void) { int ret; @@ -115,6 +140,13 @@ static int __init dell_smbios_smm_init(void) dmi_walk(find_cmd_address, NULL); + ret = test_wsmt_enabled(); + pr_debug("WSMT enable test: %d\n", ret); + if (ret) { + ret = -ENODEV; + goto fail_wsmt; + } + platform_device = platform_device_alloc("dell-smbios", 1); if (!platform_device) { ret = -ENOMEM; @@ -138,6 +170,7 @@ static int __init dell_smbios_smm_init(void) fail_platform_device_add: platform_device_put(platform_device); +fail_wsmt: fail_platform_device_alloc: free_page((unsigned long)buffer); return ret; diff --git a/drivers/platform/x86/dell-smbios.h b/drivers/platform/x86/dell-smbios.h index 8df330abeb5d..db6a16e5f87c 100644 --- a/drivers/platform/x86/dell-smbios.h +++ b/drivers/platform/x86/dell-smbios.h @@ -44,6 +44,8 @@ #define KBD_LED_AUTO_100_TOKEN 0x02F6 #define GLOBAL_MIC_MUTE_ENABLE 0x0364 #define GLOBAL_MIC_MUTE_DISABLE 0x0365 +#define WSMT_EN_TOKEN 0x04EC +#define WSMT_DIS_TOKEN 0x04ED struct notifier_block;