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=-19.4 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, URIBL_BLOCKED,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 E50FFC11F7D for ; Mon, 12 Jul 2021 08:34:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CFD2361441 for ; Mon, 12 Jul 2021 08:34:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377341AbhGLIfs (ORCPT ); Mon, 12 Jul 2021 04:35:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:35410 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349316AbhGLHuK (ORCPT ); Mon, 12 Jul 2021 03:50:10 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 2DF2A619A9; Mon, 12 Jul 2021 07:43:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626075810; bh=MD1JWawNe2ws4m20kH+0XKMRaIcFuDj9Vi/Qa8d8hoM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ht8G4o35uh4KUlrFKAm/VtSWF8KteHM8e3JnVvmAzmLlYGsa/b5ROtXPhbsMQJqKL mqx2iL5QncOTL8Jv4Fy/rIpd/M4sxCqaBI2r6BFOJcQ66K06BUfer7QbxNzQO+m3he ZwkMErgWlladi76Gzlwu8JvYvZyv2EZFC+dQgRGU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Joerg Roedel , Borislav Petkov , "Peter Zijlstra (Intel)" , Sasha Levin Subject: [PATCH 5.13 337/800] x86/sev: Make sure IRQs are disabled while GHCB is active Date: Mon, 12 Jul 2021 08:06:00 +0200 Message-Id: <20210712061002.534442696@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210712060912.995381202@linuxfoundation.org> References: <20210712060912.995381202@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 [ Upstream commit d187f217335dba2b49fc9002aab2004e04acddee ] The #VC handler only cares about IRQs being disabled while the GHCB is active, as it must not be interrupted by something which could cause another #VC while it holds the GHCB (NMI is the exception for which the backup GHCB exits). Make sure nothing interrupts the code path while the GHCB is active by making sure that callers of __sev_{get,put}_ghcb() have disabled interrupts upfront. [ bp: Massage commit message. ] Signed-off-by: Joerg Roedel Signed-off-by: Borislav Petkov Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20210618115409.22735-2-joro@8bytes.org Signed-off-by: Sasha Levin --- arch/x86/kernel/sev.c | 34 ++++++++++++++++++++++------------ 1 file changed, 22 insertions(+), 12 deletions(-) diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 651b81cd648e..396d578043d1 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -12,7 +12,6 @@ #include /* For show_regs() */ #include #include -#include #include #include #include @@ -192,11 +191,19 @@ void noinstr __sev_es_ist_exit(void) this_cpu_write(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC], *(unsigned long *)ist); } -static __always_inline struct ghcb *sev_es_get_ghcb(struct ghcb_state *state) +/* + * Nothing shall interrupt this code path while holding the per-CPU + * GHCB. The backup GHCB is only for NMIs interrupting this path. + * + * Callers must disable local interrupts around it. + */ +static noinstr struct ghcb *__sev_get_ghcb(struct ghcb_state *state) { struct sev_es_runtime_data *data; struct ghcb *ghcb; + WARN_ON(!irqs_disabled()); + data = this_cpu_read(runtime_data); ghcb = &data->ghcb_page; @@ -213,7 +220,9 @@ static __always_inline struct ghcb *sev_es_get_ghcb(struct ghcb_state *state) data->ghcb_active = false; data->backup_ghcb_active = false; + instrumentation_begin(); panic("Unable to handle #VC exception! GHCB and Backup GHCB are already in use"); + instrumentation_end(); } /* Mark backup_ghcb active before writing to it */ @@ -479,11 +488,13 @@ static enum es_result vc_slow_virt_to_phys(struct ghcb *ghcb, struct es_em_ctxt /* Include code shared with pre-decompression boot stage */ #include "sev-shared.c" -static __always_inline void sev_es_put_ghcb(struct ghcb_state *state) +static noinstr void __sev_put_ghcb(struct ghcb_state *state) { struct sev_es_runtime_data *data; struct ghcb *ghcb; + WARN_ON(!irqs_disabled()); + data = this_cpu_read(runtime_data); ghcb = &data->ghcb_page; @@ -507,7 +518,7 @@ void noinstr __sev_es_nmi_complete(void) struct ghcb_state state; struct ghcb *ghcb; - ghcb = sev_es_get_ghcb(&state); + ghcb = __sev_get_ghcb(&state); vc_ghcb_invalidate(ghcb); ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_NMI_COMPLETE); @@ -517,7 +528,7 @@ void noinstr __sev_es_nmi_complete(void) sev_es_wr_ghcb_msr(__pa_nodebug(ghcb)); VMGEXIT(); - sev_es_put_ghcb(&state); + __sev_put_ghcb(&state); } static u64 get_jump_table_addr(void) @@ -529,7 +540,7 @@ static u64 get_jump_table_addr(void) local_irq_save(flags); - ghcb = sev_es_get_ghcb(&state); + ghcb = __sev_get_ghcb(&state); vc_ghcb_invalidate(ghcb); ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_JUMP_TABLE); @@ -543,7 +554,7 @@ static u64 get_jump_table_addr(void) ghcb_sw_exit_info_2_is_valid(ghcb)) ret = ghcb->save.sw_exit_info_2; - sev_es_put_ghcb(&state); + __sev_put_ghcb(&state); local_irq_restore(flags); @@ -668,7 +679,7 @@ static void sev_es_ap_hlt_loop(void) struct ghcb_state state; struct ghcb *ghcb; - ghcb = sev_es_get_ghcb(&state); + ghcb = __sev_get_ghcb(&state); while (true) { vc_ghcb_invalidate(ghcb); @@ -685,7 +696,7 @@ static void sev_es_ap_hlt_loop(void) break; } - sev_es_put_ghcb(&state); + __sev_put_ghcb(&state); } /* @@ -1344,7 +1355,6 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication) } irq_state = irqentry_nmi_enter(regs); - lockdep_assert_irqs_disabled(); instrumentation_begin(); /* @@ -1353,7 +1363,7 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication) * keep the IRQs disabled to protect us against concurrent TLB flushes. */ - ghcb = sev_es_get_ghcb(&state); + ghcb = __sev_get_ghcb(&state); vc_ghcb_invalidate(ghcb); result = vc_init_em_ctxt(&ctxt, regs, error_code); @@ -1361,7 +1371,7 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication) if (result == ES_OK) result = vc_handle_exitcode(&ctxt, ghcb, error_code); - sev_es_put_ghcb(&state); + __sev_put_ghcb(&state); /* Done - now check the result */ switch (result) { -- 2.30.2