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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BCCD8CCA468 for ; Wed, 1 Jun 2022 13:54:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353383AbiFANym (ORCPT ); Wed, 1 Jun 2022 09:54:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58590 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353653AbiFANyO (ORCPT ); Wed, 1 Jun 2022 09:54:14 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E60148A316; Wed, 1 Jun 2022 06:53:52 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 8C211CE1AF2; Wed, 1 Jun 2022 13:53:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C9F83C385B8; Wed, 1 Jun 2022 13:53:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1654091605; bh=rZ2OXPCITf7LRFHCb0HH1soMLzMUo8JEpL8zp4zSYqI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BuCUyXu8NVvp17J32+59pk2pCD+2t7bIRO/8sMAMipZwd8nb0glmW8AXkt82SfRD8 UPcaildFOG5UUMXaIcw1v4eHDcL7cOTz3rPRR0nDxYJt53OuRlBnXphkjit4LcuoGW x6uO1yksx0lw9M1QSSuCgRMxOJLbr1bPn2/TFj2zteQrw7JiRAvZPGhhXyrQlIkpNC jZGBmmqIhW18M5Tqwq6EHEqJ+25wyebl8GFFFk6jbBuYdlFLMLY1r77kTGaQXQTdwE wOsq6sEOdZ4DUutFWeF6pTmrwO8gV782mp7AVUAr50Ar2m89v28a/leyoMcs6uyTtR 4ej1K+zBcfZQg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Laurent Dufour , Nicholas Piggin , Michael Ellerman , Sasha Levin , christophe.leroy@csgroup.eu, nathanl@linux.ibm.com, adobriyan@gmail.com, sourabhjain@linux.ibm.com, linuxppc-dev@lists.ozlabs.org Subject: [PATCH AUTOSEL 5.18 30/49] powerpc/rtas: Keep MSR[RI] set when calling RTAS Date: Wed, 1 Jun 2022 09:51:54 -0400 Message-Id: <20220601135214.2002647-30-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220601135214.2002647-1-sashal@kernel.org> References: <20220601135214.2002647-1-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Laurent Dufour [ Upstream commit b6b1c3ce06ca438eb24e0f45bf0e63ecad0369f5 ] RTAS runs in real mode (MSR[DR] and MSR[IR] unset) and in 32-bit big endian mode (MSR[SF,LE] unset). The change in MSR is done in enter_rtas() in a relatively complex way, since the MSR value could be hardcoded. Furthermore, a panic has been reported when hitting the watchdog interrupt while running in RTAS, this leads to the following stack trace: watchdog: CPU 24 Hard LOCKUP watchdog: CPU 24 TB:997512652051031, last heartbeat TB:997504470175378 (15980ms ago) ... Supported: No, Unreleased kernel CPU: 24 PID: 87504 Comm: drmgr Kdump: loaded Tainted: G E X 5.14.21-150400.71.1.bz196362_2-default #1 SLE15-SP4 (unreleased) 0d821077ef4faa8dfaf370efb5fdca1fa35f4e2c NIP: 000000001fb41050 LR: 000000001fb4104c CTR: 0000000000000000 REGS: c00000000fc33d60 TRAP: 0100 Tainted: G E X (5.14.21-150400.71.1.bz196362_2-default) MSR: 8000000002981000 CR: 48800002 XER: 20040020 CFAR: 000000000000011c IRQMASK: 1 GPR00: 0000000000000003 ffffffffffffffff 0000000000000001 00000000000050dc GPR04: 000000001ffb6100 0000000000000020 0000000000000001 000000001fb09010 GPR08: 0000000020000000 0000000000000000 0000000000000000 0000000000000000 GPR12: 80040000072a40a8 c00000000ff8b680 0000000000000007 0000000000000034 GPR16: 000000001fbf6e94 000000001fbf6d84 000000001fbd1db0 000000001fb3f008 GPR20: 000000001fb41018 ffffffffffffffff 000000000000017f fffffffffffff68f GPR24: 000000001fb18fe8 000000001fb3e000 000000001fb1adc0 000000001fb1cf40 GPR28: 000000001fb26000 000000001fb460f0 000000001fb17f18 000000001fb17000 NIP [000000001fb41050] 0x1fb41050 LR [000000001fb4104c] 0x1fb4104c Call Trace: Instruction dump: XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX Oops: Unrecoverable System Reset, sig: 6 [#1] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries ... Supported: No, Unreleased kernel CPU: 24 PID: 87504 Comm: drmgr Kdump: loaded Tainted: G E X 5.14.21-150400.71.1.bz196362_2-default #1 SLE15-SP4 (unreleased) 0d821077ef4faa8dfaf370efb5fdca1fa35f4e2c NIP: 000000001fb41050 LR: 000000001fb4104c CTR: 0000000000000000 REGS: c00000000fc33d60 TRAP: 0100 Tainted: G E X (5.14.21-150400.71.1.bz196362_2-default) MSR: 8000000002981000 CR: 48800002 XER: 20040020 CFAR: 000000000000011c IRQMASK: 1 GPR00: 0000000000000003 ffffffffffffffff 0000000000000001 00000000000050dc GPR04: 000000001ffb6100 0000000000000020 0000000000000001 000000001fb09010 GPR08: 0000000020000000 0000000000000000 0000000000000000 0000000000000000 GPR12: 80040000072a40a8 c00000000ff8b680 0000000000000007 0000000000000034 GPR16: 000000001fbf6e94 000000001fbf6d84 000000001fbd1db0 000000001fb3f008 GPR20: 000000001fb41018 ffffffffffffffff 000000000000017f fffffffffffff68f GPR24: 000000001fb18fe8 000000001fb3e000 000000001fb1adc0 000000001fb1cf40 GPR28: 000000001fb26000 000000001fb460f0 000000001fb17f18 000000001fb17000 NIP [000000001fb41050] 0x1fb41050 LR [000000001fb4104c] 0x1fb4104c Call Trace: Instruction dump: XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX ---[ end trace 3ddec07f638c34a2 ]--- This happens because MSR[RI] is unset when entering RTAS but there is no valid reason to not set it here. RTAS is expected to be called with MSR[RI] as specified in PAPR+ section "7.2.1 Machine State": R1–7.2.1–9. If called with MSR[RI] equal to 1, then RTAS must protect its own critical regions from recursion by setting the MSR[RI] bit to 0 when in the critical regions. Fixing this by reviewing the way MSR is compute before calling RTAS. Now a hardcoded value meaning real mode, 32 bits big endian mode and Recoverable Interrupt is loaded. In the case MSR[S] is set, it will remain set while entering RTAS as only urfid can unset it (thanks Fabiano). In addition a check is added in do_enter_rtas() to detect calls made with MSR[RI] unset, as we are forcing it on later. This patch has been tested on the following machines: Power KVM Guest P8 S822L (host Ubuntu kernel 5.11.0-49-generic) PowerVM LPAR P8 9119-MME (FW860.A1) p9 9008-22L (FW950.00) P10 9080-HEX (FW1010.00) Suggested-by: Nicholas Piggin Signed-off-by: Laurent Dufour Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220504101244.12107-1-ldufour@linux.ibm.com Signed-off-by: Sasha Levin --- arch/powerpc/kernel/entry_64.S | 24 ++++++++++++------------ arch/powerpc/kernel/rtas.c | 9 +++++++++ 2 files changed, 21 insertions(+), 12 deletions(-) diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 9581906b5ee9..da18f83ef883 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -330,22 +330,22 @@ _GLOBAL(enter_rtas) clrldi r4,r4,2 /* convert to realmode address */ mtlr r4 - li r0,0 - ori r0,r0,MSR_EE|MSR_SE|MSR_BE|MSR_RI - andc r0,r6,r0 - - li r9,1 - rldicr r9,r9,MSR_SF_LG,(63-MSR_SF_LG) - ori r9,r9,MSR_IR|MSR_DR|MSR_FE0|MSR_FE1|MSR_FP|MSR_RI|MSR_LE - andc r6,r0,r9 - __enter_rtas: - sync /* disable interrupts so SRR0/1 */ - mtmsrd r0 /* don't get trashed */ - LOAD_REG_ADDR(r4, rtas) ld r5,RTASENTRY(r4) /* get the rtas->entry value */ ld r4,RTASBASE(r4) /* get the rtas->base value */ + + /* + * RTAS runs in 32-bit big endian real mode, but leave MSR[RI] on as we + * may hit NMI (SRESET or MCE) while in RTAS. RTAS should disable RI in + * its critical regions (as specified in PAPR+ section 7.2.1). MSR[S] + * is not impacted by RFI_TO_KERNEL (only urfid can unset it). So if + * MSR[S] is set, it will remain when entering RTAS. + */ + LOAD_REG_IMMEDIATE(r6, MSR_ME | MSR_RI) + + li r0,0 + mtmsrd r0,1 /* disable RI before using SRR0/1 */ mtspr SPRN_SRR0,r5 mtspr SPRN_SRR1,r6 diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index 1f42aabbbab3..6bc89d9ccf63 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -49,6 +49,15 @@ void enter_rtas(unsigned long); static inline void do_enter_rtas(unsigned long args) { + unsigned long msr; + + /* + * Make sure MSR[RI] is currently enabled as it will be forced later + * in enter_rtas. + */ + msr = mfmsr(); + BUG_ON(!(msr & MSR_RI)); + enter_rtas(args); srr_regs_clobbered(); /* rtas uses SRRs, invalidate */ -- 2.35.1