From patchwork Mon Oct 9 22:51:50 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Limonciello, Mario" X-Patchwork-Id: 9994493 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 70E3360230 for ; Mon, 9 Oct 2017 22:54:27 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 629F422299 for ; Mon, 9 Oct 2017 22:54:27 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 571B422B39; Mon, 9 Oct 2017 22:54:27 +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=ham 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 03FC322064 for ; Mon, 9 Oct 2017 22:54:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755588AbdJIWyY (ORCPT ); Mon, 9 Oct 2017 18:54:24 -0400 Received: from esa6.dell-outbound.iphmx.com ([68.232.149.229]:32812 "EHLO esa6.dell-outbound.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755460AbdJIWv7 (ORCPT ); Mon, 9 Oct 2017 18:51:59 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=dell.com; i=@dell.com; q=dns/txt; s=smtpout; t=1507589519; x=1539125519; h=from:to:cc:subject:date:message-id; bh=lkljOnEEIC75/3vnVn9+vC8uVHo4vgNN5C5WIHBYu5I=; b=t1V4SpoFxw9vlY2+RAe7wxpjzXXZJ5JKDdER0MQtH4wYKgdPOKH1oCTX lL33g0k3gHlJ+Mlc5VdNwjtzoHlOGu84b/un+jOPDtBGmHnwYi91cEfGs 25Xgw/cMRNVXYYa4HUOSjf9oklziQeFiRvvKQXGYFfT5E+KgQe/o5mR63 M=; Received: from esa6.dell-outbound2.iphmx.com ([68.232.154.99]) by esa6.dell-outbound.iphmx.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 09 Oct 2017 17:51:57 -0500 Received: from ausc60ps301.us.dell.com ([143.166.148.206]) by esa6.dell-outbound2.iphmx.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 10 Oct 2017 04:51:57 +0600 X-LoopCount0: from 10.208.86.39 X-IronPort-AV: E=Sophos;i="5.42,501,1500958800"; d="scan'208";a="1042306273" 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 , Mario Limonciello Subject: [PATCH v6 12/14] platform/x86: dell-smbios-smm: test for WSMT Date: Mon, 9 Oct 2017 17:51:50 -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 --- drivers/platform/x86/dell-smbios-smm.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/drivers/platform/x86/dell-smbios-smm.c b/drivers/platform/x86/dell-smbios-smm.c index 223531e43fea..ba315753e847 100644 --- a/drivers/platform/x86/dell-smbios-smm.c +++ b/drivers/platform/x86/dell-smbios-smm.c @@ -25,6 +25,8 @@ static struct calling_interface_buffer *buffer; struct platform_device *platform_device; static DEFINE_MUTEX(smm_mutex); +#define WSMT_EN_TOKEN 0x04EC + static const struct dmi_system_id dell_device_table[] __initconst = { { .ident = "Dell laptop", @@ -76,6 +78,30 @@ int dell_smbios_smm_call(struct calling_interface_buffer *input) return 0; } +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 = 0; + buffer->select = 0; + 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; @@ -88,6 +114,13 @@ static int __init dell_smbios_smm_init(void) return -ENOMEM; dell_smbios_get_smm_address(&da_command_address, &da_command_code); + 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; @@ -111,6 +144,7 @@ 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;