From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 45363824B3; Mon, 15 Apr 2024 14:37:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713191855; cv=none; b=fyVwwFnwO2ome20HYYcmrSD68/DifOnfyAdNbnx4xj5C8Fkw1qvmqQY6n6tIr+PAi8ncEx4qy28WClySKvbPavv5vfpIPh7X9q8raqhuJL4/Xlee6YDetK71JeMZTz7eUd9+ZFXuV1Zc81mZK5MxvmZwqdfaDi/Pi4+HferqHUI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713191855; c=relaxed/simple; bh=bHkLUvy2IdHI6zsjHnJ/vwD3NqeqWwxTSAlKedgSwN0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=u8pTROkVq4c73TNWqxor/z7yAtQ1qSkslJQgXdyBXvmyTqk8tiXlIkDg5GeEBrvDbK95YqxysRXeA878WDpUK5EDXsH/Es2QxU06Od+HNc5p/QfRlfkTA48CTqnpfTc/3IPojBue0GIRPWs8Zjnk1Mn2vl8dP33V4rKO6MHXrzc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=zGULawWm; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="zGULawWm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 91B25C113CC; Mon, 15 Apr 2024 14:37:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1713191855; bh=bHkLUvy2IdHI6zsjHnJ/vwD3NqeqWwxTSAlKedgSwN0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zGULawWm7XloL4W3QzgdmwulaSxKm58Hp1C2Q6GC6AyBamoeWmaKc1DOo7bBbJrQS TfcZG0kBSMK2c85HTdihl4QiMQNzmU38j8Lm4Am6Ztg9nSCusiagwIRSBS614TFvyK 44lEIfJAsD/J+w6eDsuuegDxNVt9GpJmA1kyv/34= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Josh Poimboeuf , Ingo Molnar , Nikolay Borisov , Linus Torvalds , Sean Christopherson Subject: [PATCH 6.6 108/122] x86/bugs: Fix BHI documentation Date: Mon, 15 Apr 2024 16:21:13 +0200 Message-ID: <20240415141956.614101730@linuxfoundation.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240415141953.365222063@linuxfoundation.org> References: <20240415141953.365222063@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Josh Poimboeuf commit dfe648903f42296866d79f10d03f8c85c9dfba30 upstream. Fix up some inaccuracies in the BHI documentation. Fixes: ec9404e40e8f ("x86/bhi: Add BHI mitigation knob") Signed-off-by: Josh Poimboeuf Signed-off-by: Ingo Molnar Reviewed-by: Nikolay Borisov Cc: Linus Torvalds Cc: Sean Christopherson Link: https://lore.kernel.org/r/8c84f7451bfe0dd08543c6082a383f390d4aa7e2.1712813475.git.jpoimboe@kernel.org Signed-off-by: Greg Kroah-Hartman --- Documentation/admin-guide/hw-vuln/spectre.rst | 15 ++++++++------- Documentation/admin-guide/kernel-parameters.txt | 12 +++++++----- 2 files changed, 15 insertions(+), 12 deletions(-) --- a/Documentation/admin-guide/hw-vuln/spectre.rst +++ b/Documentation/admin-guide/hw-vuln/spectre.rst @@ -439,11 +439,11 @@ The possible values in this file are: - System is protected by retpoline * - BHI: BHI_DIS_S - System is protected by BHI_DIS_S - * - BHI: SW loop; KVM SW loop + * - BHI: SW loop, KVM SW loop - System is protected by software clearing sequence * - BHI: Syscall hardening - Syscalls are hardened against BHI - * - BHI: Syscall hardening; KVM: SW loop + * - BHI: Syscall hardening, KVM: SW loop - System is protected from userspace attacks by syscall hardening; KVM is protected by software clearing sequence Full mitigation might require a microcode update from the CPU @@ -666,13 +666,14 @@ kernel command line. of the HW BHI control and the SW BHB clearing sequence. on - unconditionally enable. + (default) Enable the HW or SW mitigation as + needed. off - unconditionally disable. + Disable the mitigation. auto - enable if hardware mitigation - control(BHI_DIS_S) is available, otherwise - enable alternate mitigation in KVM. + Enable the HW mitigation if needed, but + *don't* enable the SW mitigation except for KVM. + The system may be vulnerable. For spectre_v2_user see Documentation/admin-guide/kernel-parameters.txt --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3343,6 +3343,7 @@ reg_file_data_sampling=off [X86] retbleed=off [X86] spec_store_bypass_disable=off [X86,PPC] + spectre_bhi=off [X86] spectre_v2_user=off [X86] srbds=off [X86,INTEL] ssbd=force-off [ARM64] @@ -5926,11 +5927,12 @@ deployment of the HW BHI control and the SW BHB clearing sequence. - on - unconditionally enable. - off - unconditionally disable. - auto - (default) enable hardware mitigation - (BHI_DIS_S) if available, otherwise enable - alternate mitigation in KVM. + on - (default) Enable the HW or SW mitigation + as needed. + off - Disable the mitigation. + auto - Enable the HW mitigation if needed, but + *don't* enable the SW mitigation except + for KVM. The system may be vulnerable. spectre_v2= [X86] Control mitigation of Spectre variant 2 (indirect branch speculation) vulnerability.