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 DAEACC433F5 for ; Fri, 26 Nov 2021 10:24:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1376995AbhKZK1h (ORCPT ); Fri, 26 Nov 2021 05:27:37 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37746 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235522AbhKZKZU (ORCPT ); Fri, 26 Nov 2021 05:25:20 -0500 Received: from mail-pj1-x102f.google.com (mail-pj1-x102f.google.com [IPv6:2607:f8b0:4864:20::102f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 290A3C0613B4 for ; Fri, 26 Nov 2021 02:13:33 -0800 (PST) Received: by mail-pj1-x102f.google.com with SMTP id gf14-20020a17090ac7ce00b001a7a2a0b5c3so9561757pjb.5 for ; Fri, 26 Nov 2021 02:13:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=JXRYlHaZYG2aFI4DCBWmOyqizmtvtzTxNVeiLJn6Liw=; b=NXvDV1+/fzA2CizuNZYQxLIw2PNSdBaninuQel72zra8uVnirnP7c5Tx5twXlU7Be9 qB/QazdJ2KS2tCV+qyktWjrLbd1X7kS9AF6veiwYBTSPAN56lWM7WkXN/RUwL7WrhViX FlWbRwD2Yyc/TSKT7AGDS7MjxOXkup0ji07ZvDLo621rDLTM9q3uw1QBbQr2XShJMmiR H3/9ta7knHKir7wk0yOxAN1zmHlPTq4jjjREkUejkkA9K+NE9GAu7hkJHXGOeDjcb0ZJ KM3QKwhI7gz8Q3EezUmokUP/H1vkuZa54rXVi3k5no6EVEXTXk+X+Pt0F9R02ezSb30l /xJA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=JXRYlHaZYG2aFI4DCBWmOyqizmtvtzTxNVeiLJn6Liw=; b=Ue40yXjNDOnSOVuBQZo6Q4JXilpJyatRRedAzJ9lkBPsWazd1y4El9gaCrq6faMd2X J2si0biQTWvvDa8S0jHlzKyljeKNIY+r7c+1djy5z+BcCpV+8Ut3EHjlOrFVq0lTV577 9hO8Jjwm74SSSMet+uBMbt3Jb79ewuuYWmkI35VMPf80oRBDixbnnfQJy4s3g1iuC4gY sI5Tkm8QVi4aQXSvswV7L42nINzYpwmWGzD8j5x6sWYMEyKtzyTg6QsYMQrfDIjQ5fIa HPjgLOHSS2Aup1PyueeR4pL06yRp6DKrLllv8RLllllVDexndFbiJsRVZFO3FDjEBQCw AEOQ== X-Gm-Message-State: AOAM532PNH4MsTaL404GIHZ6s7uVn3/PWzT1kIcxsotE7wMQUiEsnJz/ PjpBwM+aIq1yttyGJ1+IUe7WdmosiKw= X-Google-Smtp-Source: ABdhPJzQACgSP/rcaj16A3WczF696dR8rlqYW5T3NwOfuA6MQxalFTv3pESk/hti2UXSP5vjhFhmpQ== X-Received: by 2002:a17:90b:3ec4:: with SMTP id rm4mr14254669pjb.88.1637921612586; Fri, 26 Nov 2021 02:13:32 -0800 (PST) Received: from localhost ([47.251.3.230]) by smtp.gmail.com with ESMTPSA id g9sm7159917pfj.160.2021.11.26.02.13.31 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 26 Nov 2021 02:13:32 -0800 (PST) From: Lai Jiangshan To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, Lai Jiangshan , Josh Poimboeuf , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" Subject: [PATCH V6 15/49] x86/traps: Add fence_swapgs_{user,kernel}_entry() Date: Fri, 26 Nov 2021 18:11:35 +0800 Message-Id: <20211126101209.8613-16-jiangshanlai@gmail.com> X-Mailer: git-send-email 2.19.1.6.gb485710b In-Reply-To: <20211126101209.8613-1-jiangshanlai@gmail.com> References: <20211126101209.8613-1-jiangshanlai@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lai Jiangshan fence_swapgs_{user,kernel}_entry() in entry64.c are the same as the ASM macro FENCE_SWAPGS_{USER,KERNEL}_ENTRY. fence_swapgs_user_entry is used in the user entry swapgs code path, to prevent a speculative swapgs when coming from kernel space. fence_swapgs_kernel_entry is used in the kernel entry code path, to prevent the swapgs from getting speculatively skipped when coming from user space. Cc: Josh Poimboeuf Signed-off-by: Lai Jiangshan --- arch/x86/entry/entry64.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/arch/x86/entry/entry64.c b/arch/x86/entry/entry64.c index 9a5c535b1ddf..bdc9540f25d3 100644 --- a/arch/x86/entry/entry64.c +++ b/arch/x86/entry/entry64.c @@ -38,3 +38,24 @@ static __always_inline void switch_to_kernel_cr3(void) #else static __always_inline void switch_to_kernel_cr3(void) {} #endif + +/* + * Mitigate Spectre v1 for conditional swapgs code paths. + * + * fence_swapgs_user_entry is used in the user entry swapgs code path, to + * prevent a speculative swapgs when coming from kernel space. It must be + * used with switch_to_kernel_cr3() in the same path. + * + * fence_swapgs_kernel_entry is used in the kernel entry code path without + * CR3 write or with conditinal CR3 write only, to prevent the swapgs from + * getting speculatively skipped when coming from user space. + */ +static __always_inline void fence_swapgs_user_entry(void) +{ + alternative("", "lfence", X86_FEATURE_FENCE_SWAPGS_USER); +} + +static __always_inline void fence_swapgs_kernel_entry(void) +{ + alternative("", "lfence", X86_FEATURE_FENCE_SWAPGS_KERNEL); +} -- 2.19.1.6.gb485710b