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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A206EC19F2B for ; Wed, 27 Jul 2022 17:45:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243040AbiG0RpP (ORCPT ); Wed, 27 Jul 2022 13:45:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46662 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243318AbiG0Rol (ORCPT ); Wed, 27 Jul 2022 13:44:41 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0E53B8C153; Wed, 27 Jul 2022 09:53:22 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 0F0DEB821D7; Wed, 27 Jul 2022 16:53:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 53D6BC433C1; Wed, 27 Jul 2022 16:53:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658940798; bh=hgedp9WsWU6gyxMX4x+e4LsYusxnvmMwzm2vb72HzhM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SraCPUtZDKSAFdA6sZ517BQ1RPSxQX5Qjt+X0yLA3bK3cIi55RFI1mA3Gb8a131bW o1vdOM7Qr69CssgpoxMZZu/eyto8lZWSH3A174dHBm3h+ZMaikmVoHThhwBnQfS0Yx WMGAlMnDqUACaCoEIdA8EKWnE9ZEUpl6dxY1QJWE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Peter Zijlstra (Intel)" , Borislav Petkov Subject: [PATCH 5.18 152/158] x86/amd: Use IBPB for firmware calls Date: Wed, 27 Jul 2022 18:13:36 +0200 Message-Id: <20220727161027.443092336@linuxfoundation.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220727161021.428340041@linuxfoundation.org> References: <20220727161021.428340041@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Peter Zijlstra commit 28a99e95f55c61855983d36a88c05c178d966bb7 upstream. On AMD IBRS does not prevent Retbleed; as such use IBPB before a firmware call to flush the branch history state. And because in order to do an EFI call, the kernel maps a whole lot of the kernel page table into the EFI page table, do an IBPB just in case in order to prevent the scenario of poisoning the BTB and causing an EFI call using the unprotected RET there. [ bp: Massage. ] Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20220715194550.793957-1-cascardo@canonical.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/include/asm/nospec-branch.h | 2 ++ arch/x86/kernel/cpu/bugs.c | 11 ++++++++++- 3 files changed, 13 insertions(+), 1 deletion(-) --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -301,6 +301,7 @@ #define X86_FEATURE_RETPOLINE_LFENCE (11*32+13) /* "" Use LFENCE for Spectre variant 2 */ #define X86_FEATURE_RETHUNK (11*32+14) /* "" Use REturn THUNK */ #define X86_FEATURE_UNRET (11*32+15) /* "" AMD BTB untrain return */ +#define X86_FEATURE_USE_IBPB_FW (11*32+16) /* "" Use IBPB during runtime firmware calls */ /* Intel-defined CPU features, CPUID level 0x00000007:1 (EAX), word 12 */ #define X86_FEATURE_AVX_VNNI (12*32+ 4) /* AVX VNNI instructions */ --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -297,6 +297,8 @@ do { \ alternative_msr_write(MSR_IA32_SPEC_CTRL, \ spec_ctrl_current() | SPEC_CTRL_IBRS, \ X86_FEATURE_USE_IBRS_FW); \ + alternative_msr_write(MSR_IA32_PRED_CMD, PRED_CMD_IBPB, \ + X86_FEATURE_USE_IBPB_FW); \ } while (0) #define firmware_restrict_branch_speculation_end() \ --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1512,7 +1512,16 @@ static void __init spectre_v2_select_mit * the CPU supports Enhanced IBRS, kernel might un-intentionally not * enable IBRS around firmware calls. */ - if (boot_cpu_has(X86_FEATURE_IBRS) && !spectre_v2_in_ibrs_mode(mode)) { + if (boot_cpu_has_bug(X86_BUG_RETBLEED) && + (boot_cpu_data.x86_vendor == X86_VENDOR_AMD || + boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)) { + + if (retbleed_cmd != RETBLEED_CMD_IBPB) { + setup_force_cpu_cap(X86_FEATURE_USE_IBPB_FW); + pr_info("Enabling Speculation Barrier for firmware calls\n"); + } + + } else if (boot_cpu_has(X86_FEATURE_IBRS) && !spectre_v2_in_ibrs_mode(mode)) { setup_force_cpu_cap(X86_FEATURE_USE_IBRS_FW); pr_info("Enabling Restricted Speculation for firmware calls\n"); }