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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 C33B6C04FF3 for ; Mon, 24 May 2021 16:00:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A03B16109E for ; Mon, 24 May 2021 16:00:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234923AbhEXQB7 (ORCPT ); Mon, 24 May 2021 12:01:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:40490 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234369AbhEXPz3 (ORCPT ); Mon, 24 May 2021 11:55:29 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8C99861442; Mon, 24 May 2021 15:41:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621870912; bh=AverE+4Aa7g78zpNJxtYS0wKkTAxqk0TcopGG5HvzAk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aW/dVBQ67o2s1RC7l5jNKSgglMcMgh7j4Q7dODtGTVGgO8tselzTtFeXx0Q7Tk37s jNR+Ne7jzqtGtYp7MR2WMNRvSNCP8wfJ76fdq8wFlB42d8PDr13Rd0pwBqkZHkMtYW vZzkNPW1/s2VIUE2B4eGd0cXKPGVpB9J55TUDHgE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Joerg Roedel , Borislav Petkov Subject: [PATCH 5.10 057/104] x86/sev-es: Dont return NULL from sev_es_get_ghcb() Date: Mon, 24 May 2021 17:25:52 +0200 Message-Id: <20210524152334.749954290@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210524152332.844251980@linuxfoundation.org> References: <20210524152332.844251980@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Joerg Roedel commit b250f2f7792d15bcde98e0456781e2835556d5fa upstream. 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 Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/sev-es.c | 25 ++++++++++++------------- 1 file changed, 12 insertions(+), 13 deletions(-) --- a/arch/x86/kernel/sev-es.c +++ b/arch/x86/kernel/sev-es.c @@ -191,8 +191,18 @@ static __always_inline struct ghcb *sev_ 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; @@ -1262,7 +1272,6 @@ static __always_inline bool on_vc_fallba */ 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; @@ -1288,16 +1297,6 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_co */ 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);