From patchwork Mon Jul 12 06:06:31 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 475775 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=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 A4B74C11F68 for ; Mon, 12 Jul 2021 07:10:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8A56F613F4 for ; Mon, 12 Jul 2021 07:10:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233742AbhGLHNn (ORCPT ); Mon, 12 Jul 2021 03:13:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:46696 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242815AbhGLHMK (ORCPT ); Mon, 12 Jul 2021 03:12:10 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1B2986108B; Mon, 12 Jul 2021 07:09:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626073762; bh=p0dhTNl3jvXzHiHMy3rCGHaQQhWGEnT3keM+VaVJG1s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LOQ+Uu7hQimIxPTvMh+rf8WuvZvpjuYkMEWiKrCu6FfBMOFZTd+wC30Ayy73MxxTW huGp/vH6JrD7aAk2XIrW8WZSmoxnKClB5tHWnrHAAX1RiQGBOhoirsUuGsJspwPJOt As2zfPL5tmA5sklDV6pDk2sN7wDTNc4MGgA7OKCs= 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 5.12 308/700] x86/sev: Make sure IRQs are disabled while GHCB is active Date: Mon, 12 Jul 2021 08:06:31 +0200 Message-Id: <20210712061009.149709173@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210712060924.797321836@linuxfoundation.org> References: <20210712060924.797321836@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@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-es.c | 34 ++++++++++++++++++++++------------ 1 file changed, 22 insertions(+), 12 deletions(-) diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c index e0cdab7cb632..0b5e35a51804 100644 --- a/arch/x86/kernel/sev-es.c +++ b/arch/x86/kernel/sev-es.c @@ -12,7 +12,6 @@ #include /* For show_regs() */ #include #include -#include #include #include #include @@ -180,11 +179,19 @@ 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; @@ -201,7 +208,9 @@ 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 */ @@ -452,11 +461,13 @@ 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-es-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; @@ -480,7 +491,7 @@ 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); @@ -490,7 +501,7 @@ 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) @@ -502,7 +513,7 @@ 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); @@ -516,7 +527,7 @@ 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); @@ -641,7 +652,7 @@ 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); @@ -658,7 +669,7 @@ static void sev_es_ap_hlt_loop(void) break; } - sev_es_put_ghcb(&state); + __sev_put_ghcb(&state); } /* @@ -1317,7 +1328,6 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication) } irq_state = irqentry_nmi_enter(regs); - lockdep_assert_irqs_disabled(); instrumentation_begin(); /* @@ -1326,7 +1336,7 @@ 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); @@ -1334,7 +1344,7 @@ 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) {