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 A09971EEE3; Mon, 15 Apr 2024 14:41:14 +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=1713192074; cv=none; b=NeQE4T+pZ5NMcGvsl8j+tRGxqMelYgHU2qSjkBXPMVpBvviLzSzwh381/Bs4dC6cg5nnBpcAncfKdqyD+KTVkQaWKPglZ4bP/z1K0Mt79xRMBTIj6kUI/Qsd4jmFIKrCIqjQFlEV6t7oKMVZIHTHypngNQhJIRv7vOWWChGtBD4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713192074; c=relaxed/simple; bh=QI1Zu2BnxMJlSqHHBG3h77rbbA3kUIIsX4nF3qTlAqs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=FybQSMNTk88vRn/BfijYv9+WSiE4A3Pev4Brl7S2dg0HJ2WLpRa5+U0yjxF52XE3gHJkBWAgv8lSAnuydFuHElaDtDc+oH+wDvHJUYXmdaadYvxdSvfFCt53ws6XNMjHwIsiQCn97P0djh/Ox7LJp5mF3laz2HG9bQqyLb5aw8k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=RpoHKuCP; 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="RpoHKuCP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 248C4C113CC; Mon, 15 Apr 2024 14:41:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1713192074; bh=QI1Zu2BnxMJlSqHHBG3h77rbbA3kUIIsX4nF3qTlAqs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RpoHKuCPV2qWPLvKfcJq+mwbm5DC1KiwhKRKhoaU+c4/lEn9lqGQtL4Fwsax4IQK6 OBtup9N/UoLoGSrzpA40qhAg6mR3GsHlwUSFHQPpIyUY40mBIjj+cwZHnqOE4uOy+q VK8rJb6XEclrHYN3BU5sWhdNFvHraoObTU0AweME= 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 6.1 58/69] x86/bugs: Fix BHI documentation Date: Mon, 15 Apr 2024 16:21:29 +0200 Message-ID: <20240415141947.916732471@linuxfoundation.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240415141946.165870434@linuxfoundation.org> References: <20240415141946.165870434@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 6.1-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 @@ -3283,6 +3283,7 @@ 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] @@ -5739,11 +5740,12 @@ 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.