From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E35A0158D72; Tue, 9 Jul 2024 11:19:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720523977; cv=none; b=L/nAAIXHpGTdloM012+n+1UwFmgjPqFDCoCWveV7qrM0ZSFEuWgnet3a0qnPmdLP3K0r4gRqLtroA2eCa5EOj4wwaxO9CMoKv14KWfpha9P/1jZ65Y9QtHk0j6WEwbuhgEjJDwP9j139x282/M2g+4YvwCyzz65jHR9ZIHOHrIs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720523977; c=relaxed/simple; bh=lSZtLaCA5G6yFpiOKVcV33XvZ5GBp6z0HOzV2WyFAgc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jJUsoE5UCoZbAwtgGWiSnfpQdTbIZB4pPO7RjgjcxFlnESKaNviOhkZLpjuLCm63ULysan6gf1PnbDJBCIARha3NUAibWrha+LXVuyvKVWk8jzBPw6gw8pukGkTD/a+/falYkW2Z5hv6V4n+mTxuX9gsdWjtzMpdHpGTQeVdOys= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=byfUoWrR; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="byfUoWrR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 69B41C4AF0B; Tue, 9 Jul 2024 11:19:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1720523976; bh=lSZtLaCA5G6yFpiOKVcV33XvZ5GBp6z0HOzV2WyFAgc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=byfUoWrRCgDPVkWyz7A5Lu3WjeSl77rfh7oJit65y5vJ30mDWBJBCAM23AKIHl0Y9 KVgRhFTzCZaGqD6uOSXcmMVR68eJUdTYS0MKkQ8FtQL75UWq5Pz+cZWZOZcbJ/hFzY kJqhMA1dZ8M8Y9L7yHRmxDeGP0JE9mS4pnbY2I+Q= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Christophe Leroy , Shirisha Ganta , Mahesh Salgaonkar , Michael Ellerman , Sasha Levin Subject: [PATCH 6.9 007/197] powerpc: Avoid nmi_enter/nmi_exit in real mode interrupt. Date: Tue, 9 Jul 2024 13:07:41 +0200 Message-ID: <20240709110709.194322436@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240709110708.903245467@linuxfoundation.org> References: <20240709110708.903245467@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mahesh Salgaonkar [ Upstream commit 0db880fc865ffb522141ced4bfa66c12ab1fbb70 ] nmi_enter()/nmi_exit() touches per cpu variables which can lead to kernel crash when invoked during real mode interrupt handling (e.g. early HMI/MCE interrupt handler) if percpu allocation comes from vmalloc area. Early HMI/MCE handlers are called through DEFINE_INTERRUPT_HANDLER_NMI() wrapper which invokes nmi_enter/nmi_exit calls. We don't see any issue when percpu allocation is from the embedded first chunk. However with CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK enabled there are chances where percpu allocation can come from the vmalloc area. With kernel command line "percpu_alloc=page" we can force percpu allocation to come from vmalloc area and can see kernel crash in machine_check_early: [ 1.215714] NIP [c000000000e49eb4] rcu_nmi_enter+0x24/0x110 [ 1.215717] LR [c0000000000461a0] machine_check_early+0xf0/0x2c0 [ 1.215719] --- interrupt: 200 [ 1.215720] [c000000fffd73180] [0000000000000000] 0x0 (unreliable) [ 1.215722] [c000000fffd731b0] [0000000000000000] 0x0 [ 1.215724] [c000000fffd73210] [c000000000008364] machine_check_early_common+0x134/0x1f8 Fix this by avoiding use of nmi_enter()/nmi_exit() in real mode if percpu first chunk is not embedded. Reviewed-by: Christophe Leroy Tested-by: Shirisha Ganta Signed-off-by: Mahesh Salgaonkar Signed-off-by: Michael Ellerman Link: https://msgid.link/20240410043006.81577-1-mahesh@linux.ibm.com Signed-off-by: Sasha Levin --- arch/powerpc/include/asm/interrupt.h | 10 ++++++++++ arch/powerpc/include/asm/percpu.h | 10 ++++++++++ arch/powerpc/kernel/setup_64.c | 2 ++ 3 files changed, 22 insertions(+) diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h index 7b610864b3645..2d6c886b40f44 100644 --- a/arch/powerpc/include/asm/interrupt.h +++ b/arch/powerpc/include/asm/interrupt.h @@ -336,6 +336,14 @@ static inline void interrupt_nmi_enter_prepare(struct pt_regs *regs, struct inte if (IS_ENABLED(CONFIG_KASAN)) return; + /* + * Likewise, do not use it in real mode if percpu first chunk is not + * embedded. With CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK enabled there + * are chances where percpu allocation can come from vmalloc area. + */ + if (percpu_first_chunk_is_paged) + return; + /* Otherwise, it should be safe to call it */ nmi_enter(); } @@ -351,6 +359,8 @@ static inline void interrupt_nmi_exit_prepare(struct pt_regs *regs, struct inter // no nmi_exit for a pseries hash guest taking a real mode exception } else if (IS_ENABLED(CONFIG_KASAN)) { // no nmi_exit for KASAN in real mode + } else if (percpu_first_chunk_is_paged) { + // no nmi_exit if percpu first chunk is not embedded } else { nmi_exit(); } diff --git a/arch/powerpc/include/asm/percpu.h b/arch/powerpc/include/asm/percpu.h index 8e5b7d0b851c6..634970ce13c6b 100644 --- a/arch/powerpc/include/asm/percpu.h +++ b/arch/powerpc/include/asm/percpu.h @@ -15,6 +15,16 @@ #endif /* CONFIG_SMP */ #endif /* __powerpc64__ */ +#if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK) && defined(CONFIG_SMP) +#include +DECLARE_STATIC_KEY_FALSE(__percpu_first_chunk_is_paged); + +#define percpu_first_chunk_is_paged \ + (static_key_enabled(&__percpu_first_chunk_is_paged.key)) +#else +#define percpu_first_chunk_is_paged false +#endif /* CONFIG_PPC64 && CONFIG_SMP */ + #include #include diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c index 2f19d5e944852..ae36a129789ff 100644 --- a/arch/powerpc/kernel/setup_64.c +++ b/arch/powerpc/kernel/setup_64.c @@ -834,6 +834,7 @@ static __init int pcpu_cpu_to_node(int cpu) unsigned long __per_cpu_offset[NR_CPUS] __read_mostly; EXPORT_SYMBOL(__per_cpu_offset); +DEFINE_STATIC_KEY_FALSE(__percpu_first_chunk_is_paged); void __init setup_per_cpu_areas(void) { @@ -876,6 +877,7 @@ void __init setup_per_cpu_areas(void) if (rc < 0) panic("cannot initialize percpu area (err=%d)", rc); + static_key_enable(&__percpu_first_chunk_is_paged.key); delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start; for_each_possible_cpu(cpu) { __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu]; -- 2.43.0