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 02131C433F5 for ; Sat, 4 Dec 2021 11:45:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344434AbhLDLs5 (ORCPT ); Sat, 4 Dec 2021 06:48:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54498 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232593AbhLDLsz (ORCPT ); Sat, 4 Dec 2021 06:48:55 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 408D0C061751; Sat, 4 Dec 2021 03:45:30 -0800 (PST) Date: Sat, 04 Dec 2021 11:45:26 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1638618327; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1Rv16amoOJU48Qefvj434LiLlJQhglGv2zTakpo7RAU=; b=uLHUkgl6A9txw49je5/tPe4GTs2pG4L5pc6TgvYfVc8dUPYQmD5G/qsjew7L2F5TTnkjK8 HNc/2Xs+YEG+9//qoV10nsuJsWwi2SV/ad1YGKLY17PG4oDjocNxPlywn5s2zYzu+VOAz3 msUQSK2ULjkcnb/ca0oY3Y3XNey57xWW1xpPTKbWHhzdtaGY425GJTNPA2WQ21vc7hkxpo 8I2WuUnIL3r3kEhW26IDZsU+PPbTQHU67MhTWACxXUD38maKUE1QwOg3i4qNcORWduWYw5 2Mxc60Dg94Q68dwVY1JQdOUzTTa9dtJMj5T4bxg3XaWryA8BRsf4OlAngGV0xA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1638618327; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1Rv16amoOJU48Qefvj434LiLlJQhglGv2zTakpo7RAU=; b=7pGzpJxvKpllgV3hAtF5eCWnadpv4elxqXuJo0b9QHSrLD95XUL7dpU0xmkv/mZKvUyNw4 NNpad8Lpxqt/kfDQ== From: "tip-bot2 for Lai Jiangshan" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/urgent] x86/entry: Use the correct fence macro after swapgs in kernel CR3 Cc: Lai Jiangshan , Borislav Petkov , "Peter Zijlstra (Intel)" , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20211126101209.8613-3-jiangshanlai@gmail.com> References: <20211126101209.8613-3-jiangshanlai@gmail.com> MIME-Version: 1.0 Message-ID: <163861832657.11128.14542109186341632803.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/urgent branch of tip: Commit-ID: 1367afaa2ee90d1c956dfc224e199fcb3ff3f8cc Gitweb: https://git.kernel.org/tip/1367afaa2ee90d1c956dfc224e199fcb3ff3f8cc Author: Lai Jiangshan AuthorDate: Fri, 26 Nov 2021 18:11:22 +08:00 Committer: Borislav Petkov CommitterDate: Fri, 03 Dec 2021 19:13:53 +01:00 x86/entry: Use the correct fence macro after swapgs in kernel CR3 The commit c75890700455 ("x86/entry/64: Remove unneeded kernel CR3 switching") removed a CR3 write in the faulting path of load_gs_index(). But the path's FENCE_SWAPGS_USER_ENTRY has no fence operation if PTI is enabled, see spectre_v1_select_mitigation(). Rather, it depended on the serializing CR3 write of SWITCH_TO_KERNEL_CR3 and since it got removed, add a FENCE_SWAPGS_KERNEL_ENTRY call to make sure speculation is blocked. [ bp: Massage commit message and comment. ] Fixes: c75890700455 ("x86/entry/64: Remove unneeded kernel CR3 switching") Signed-off-by: Lai Jiangshan Signed-off-by: Borislav Petkov Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20211126101209.8613-3-jiangshanlai@gmail.com --- arch/x86/entry/entry_64.S | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index f1a8b5b..f9e1c06 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -987,11 +987,6 @@ SYM_CODE_START_LOCAL(error_entry) pushq %r12 ret -.Lerror_entry_done_lfence: - FENCE_SWAPGS_KERNEL_ENTRY -.Lerror_entry_done: - ret - /* * There are two places in the kernel that can potentially fault with * usergs. Handle them here. B stepping K8s sometimes report a @@ -1014,8 +1009,14 @@ SYM_CODE_START_LOCAL(error_entry) * .Lgs_change's error handler with kernel gsbase. */ SWAPGS - FENCE_SWAPGS_USER_ENTRY - jmp .Lerror_entry_done + + /* + * Issue an LFENCE to prevent GS speculation, regardless of whether it is a + * kernel or user gsbase. + */ +.Lerror_entry_done_lfence: + FENCE_SWAPGS_KERNEL_ENTRY + ret .Lbstep_iret: /* Fix truncated RIP */