From patchwork Thu May 20 10:22:19 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: thermal-bot for Julien Panis X-Patchwork-Id: 445568 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=-20.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING, SPF_HELO_NONE, SPF_PASS 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 CCCD4C433ED for ; Thu, 20 May 2021 10:24:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AF4556135B for ; Thu, 20 May 2021 10:24:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236306AbhETKZ3 (ORCPT ); Thu, 20 May 2021 06:25:29 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:45954 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236368AbhETKXu (ORCPT ); Thu, 20 May 2021 06:23:50 -0400 Date: Thu, 20 May 2021 10:22:19 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1621506139; 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=6BseoDTvKoUMT+QJFQEGGjbZApSjVZjrQkoWva0z5bQ=; b=eFsPWOfSQUU47ulF99G37c+vdWJdstdIyxAnwHsfnrohdl80csl4m31BrptqvzrpJf2aaW TjCov1FRzsIdmUc6gFwfZ2gFU+RRBVQ4Zmcl0XLp7NYR/9aSO1mz2J9ItMey7AfVB9rGw1 l4MkguT6wQG7i7Bp4FTuOaL+RvevIIS2oPfsrTIkkrrk9GUDAxQ+p3xawPzH96LTUAF4h0 oDyGFjoqpvtqICMT00WQRSXe9yMAyVJvW4DCAgZZaNaO0SmyhtYe7MZj5KvSp2L4qkahA4 6HXSiJ9XjN7dooWuQ8XGwBr9UkXRmZ/c2P9Ck6dOCHGMrKRAXqyXMovrlfVEAw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1621506139; 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=6BseoDTvKoUMT+QJFQEGGjbZApSjVZjrQkoWva0z5bQ=; b=PYXj3vRIocApDQ/qvsjVf7MiNaDfUCn71Y9SRHCibnYExes5i43yus6gcZYfjC8NNlNbXH /RZSPemxF3tyX6Aw== From: "tip-bot2 for Joerg Roedel" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/urgent] x86/sev-es: Don't return NULL from sev_es_get_ghcb() Cc: Joerg Roedel , Borislav Petkov , stable@vger.kernel.org, #@tip-bot2.tec.linutronix.de, v5.10+@tip-bot2.tec.linutronix.de, x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20210519135251.30093-2-joro@8bytes.org> References: <20210519135251.30093-2-joro@8bytes.org> MIME-Version: 1.0 Message-ID: <162150613911.29796.9924367580414039528.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The following commit has been merged into the x86/urgent branch of tip: Commit-ID: b250f2f7792d15bcde98e0456781e2835556d5fa Gitweb: https://git.kernel.org/tip/b250f2f7792d15bcde98e0456781e2835556d5fa Author: Joerg Roedel AuthorDate: Wed, 19 May 2021 15:52:44 +02:00 Committer: Borislav Petkov CommitterDate: Wed, 19 May 2021 17:05:13 +02:00 x86/sev-es: Don't return NULL from sev_es_get_ghcb() sev_es_get_ghcb() is called from several places but only one of them checks the return value. The reaction to returning NULL is always the same: calling panic() and kill the machine. Instead of adding checks to all call sites, move the panic() into the function itself so that it will no longer return NULL. Fixes: 0786138c78e7 ("x86/sev-es: Add a Runtime #VC Exception Handler") Signed-off-by: Joerg Roedel Signed-off-by: Borislav Petkov Cc: stable@vger.kernel.org # v5.10+ Link: https://lkml.kernel.org/r/20210519135251.30093-2-joro@8bytes.org --- arch/x86/kernel/sev.c | 25 ++++++++++++------------- 1 file changed, 12 insertions(+), 13 deletions(-) diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 4fa111b..82bced8 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -203,8 +203,18 @@ static __always_inline struct ghcb *sev_es_get_ghcb(struct ghcb_state *state) if (unlikely(data->ghcb_active)) { /* GHCB is already in use - save its contents */ - if (unlikely(data->backup_ghcb_active)) - return NULL; + if (unlikely(data->backup_ghcb_active)) { + /* + * Backup-GHCB is also already in use. There is no way + * to continue here so just kill the machine. To make + * panic() work, mark GHCBs inactive so that messages + * can be printed out. + */ + data->ghcb_active = false; + data->backup_ghcb_active = false; + + panic("Unable to handle #VC exception! GHCB and Backup GHCB are already in use"); + } /* Mark backup_ghcb active before writing to it */ data->backup_ghcb_active = true; @@ -1289,7 +1299,6 @@ static __always_inline bool on_vc_fallback_stack(struct pt_regs *regs) */ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication) { - struct sev_es_runtime_data *data = this_cpu_read(runtime_data); irqentry_state_t irq_state; struct ghcb_state state; struct es_em_ctxt ctxt; @@ -1315,16 +1324,6 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication) */ ghcb = sev_es_get_ghcb(&state); - if (!ghcb) { - /* - * Mark GHCBs inactive so that panic() is able to print the - * message. - */ - data->ghcb_active = false; - data->backup_ghcb_active = false; - - panic("Unable to handle #VC exception! GHCB and Backup GHCB are already in use"); - } vc_ghcb_invalidate(ghcb); result = vc_init_em_ctxt(&ctxt, regs, error_code);