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 X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EE107C433DB for ; Thu, 4 Feb 2021 14:29:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BE33664F42 for ; Thu, 4 Feb 2021 14:29:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236627AbhBDO3B (ORCPT ); Thu, 4 Feb 2021 09:29:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53566 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236751AbhBDO1M (ORCPT ); Thu, 4 Feb 2021 09:27:12 -0500 Received: from mail-pg1-x529.google.com (mail-pg1-x529.google.com [IPv6:2607:f8b0:4864:20::529]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3102C061788 for ; Thu, 4 Feb 2021 06:26:30 -0800 (PST) Received: by mail-pg1-x529.google.com with SMTP id t25so2216952pga.2 for ; Thu, 04 Feb 2021 06:26:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=3BIXwfOt2Imm8gRi2hLWfcGsPb8s4RQNwvxHi+wIG9g=; b=hVAR78eNebt6pCIxN0kgY0ZhycDpPhKCUkEGhy0gs+YRLRQHNZLsBhNDURXQul4m5O OS62ULYpV5Rhz5iwlhpLEN+Oz5bBakA7MDyNtqhgGzBo1FYVmFaTA954wyxUEfaG6YF+ uTPDlfM1G5YXnTlT4J5kil7nRVxILcZ/ZYdEWXYu0Dx7+A4DdBslT1/ier+uba6jLELI BHyDw3YoP1NtnEFgPk604iZa+k1GaVEdKVsmxYjppWSllgAp6T681WqFl280OcA0lkdc uF6ualI7vkgTG6rJH/jga1HPdllB96+xAjm+SmsBAZfCacDWPKM1dKAnM4P6+r94uv+n jHhg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=3BIXwfOt2Imm8gRi2hLWfcGsPb8s4RQNwvxHi+wIG9g=; b=ZWjIUokYZFB+sqUspHHFWitdHOgWbdO3DHve6vYBfFng8lQ25EZ4wmOfgrWOT+i3Ag Zp4wpwOARVDUAEb0MyFZsWjIiBZEBjeBKV7zDd0YkWPoTSqRw5qzQvMIE56My5dzhhXt ADJzKBFtT0PnM5priifiGGycOpHMmZh5TdxoMXBCjA4WC66owvdJzYABSNDbnR/gqJKn AgC0DDcExiwx6S/jiLL6ztQy+ulKr2JP35zysmVOBlXiHtwFqPgY1Nc+rQUkGRsZ2+nd eVFwFtkbxrt9o0e3p3x23KOY9P15LSPuyA/7REavBYtyzz9oTjLNX1MdB1vTiK9fZ0Fs OE5A== X-Gm-Message-State: AOAM5307pjKabHXQ6xf9ga2BOLeMQ3Bm6I1+/ytZe3rCNd11D3Ud9ugX whHmEoURpbB7LP7BHkyala+NIVh5u6A= X-Google-Smtp-Source: ABdhPJwYYz8kUZFXDErKVSlxvr2RVqWotIaxHorxMxxfbIOzmBwo0sUN2IZtIaEYSmnEQ5TxO2XGCg== X-Received: by 2002:a63:2d46:: with SMTP id t67mr9243323pgt.242.1612448790129; Thu, 04 Feb 2021 06:26:30 -0800 (PST) Received: from localhost ([47.251.4.198]) by smtp.gmail.com with ESMTPSA id w205sm6351513pfc.198.2021.02.04.06.26.29 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 04 Feb 2021 06:26:29 -0800 (PST) From: Lai Jiangshan To: linux-kernel@vger.kernel.org Cc: Lai Jiangshan , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Peter Zijlstra , Alexandre Chartre , Andy Lutomirski , "Gustavo A. R. Silva" Subject: [PATCH 2/2] x86/hw_breakpoint: Prevent data breakpoints on cpu_dr7 Date: Thu, 4 Feb 2021 23:27:07 +0800 Message-Id: <20210204152708.21308-2-jiangshanlai@gmail.com> X-Mailer: git-send-email 2.19.1.6.gb485710b In-Reply-To: <20210204152708.21308-1-jiangshanlai@gmail.com> References: <20210204152708.21308-1-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 When in guest (X86_FEATURE_HYPERVISOR), local_db_save() will read per-cpu cpu_dr7 before clear dr7 register. local_db_save() is called at the start of exc_debug_kernel(). To avoid recursive #DB, we have to disallow data breakpoints on cpu_dr7. Fixes: 84b6a3491567a("x86/entry: Optimize local_db_save() for virt") Signed-off-by: Lai Jiangshan --- arch/x86/kernel/hw_breakpoint.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c index bc7493a0736f..de34dd49d317 100644 --- a/arch/x86/kernel/hw_breakpoint.c +++ b/arch/x86/kernel/hw_breakpoint.c @@ -307,6 +307,14 @@ static inline bool within_cpu_entry(unsigned long addr, unsigned long end) (unsigned long)&per_cpu(cpu_tlbstate, cpu), sizeof(struct tlb_state))) return true; + + /* + * When in guest (X86_FEATURE_HYPERVISOR), local_db_save() + * will read per-cpu cpu_dr7 before clear dr7 register. + */ + if (within_area(addr, end, (unsigned long)&per_cpu(cpu_dr7, cpu), + sizeof(cpu_dr7))) + return true; } return false; -- 2.19.1.6.gb485710b