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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 403E7CA9EC0 for ; Tue, 29 Oct 2019 02:11:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 053B2218AC for ; Tue, 29 Oct 2019 02:11:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KDApa/4f" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729673AbfJ2CLf (ORCPT ); Mon, 28 Oct 2019 22:11:35 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:46598 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726526AbfJ2CLf (ORCPT ); Mon, 28 Oct 2019 22:11:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1572315094; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Hnh/cEOnCtz15+Vm+cdDfXEaQONmAZZKvLF31txQOks=; b=KDApa/4fr0daAX0WJyXFtbwwG7b35Ylexk1Vg9mr7suwXMf1jNsTyu6/Wx5KtmFNXbQmXP hGHRrFRvXVwbFnBGA2SiA9vpt7bVmo8bYGfAnbdvWaOzM0rJD5kkQcMAWpDqa0OVlLV4cm Nc34Rox98v17YLE/5IG+sIJ1el8Vu2M= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-325-qwYsCiBGN7Ct6PQCfzJ_-g-1; Mon, 28 Oct 2019 22:11:30 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 14F93107AD28; Tue, 29 Oct 2019 02:11:29 +0000 (UTC) Received: from localhost.localdomain.com (ovpn-12-41.pek2.redhat.com [10.72.12.41]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4B83A1000180; Tue, 29 Oct 2019 02:11:17 +0000 (UTC) From: Lianbo Jiang To: linux-kernel@vger.kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org, bhe@redhat.com, dyoung@redhat.com, jgross@suse.com, dhowells@redhat.com, Thomas.Lendacky@amd.com, ebiederm@xmission.com, vgoyal@redhat.com, d.hatayama@fujitsu.com, horms@verge.net.au, kexec@lists.infradead.org Subject: [PATCH 1/2 v7] x86/kdump: always reserve the low 1MiB when the crashkernel option is specified Date: Tue, 29 Oct 2019 10:10:58 +0800 Message-Id: <20191029021059.22070-2-lijiang@redhat.com> In-Reply-To: <20191029021059.22070-1-lijiang@redhat.com> References: <20191029021059.22070-1-lijiang@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-MC-Unique: qwYsCiBGN7Ct6PQCfzJ_-g-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Kdump kernel will reuse the first 640k region because the real mode trampoline has to work in this area. When the vmcore is dumped, the old memory in this area may be accessed, therefore, kernel has to copy the contents of the first 640k area to a backup region so that kdump kernel can read the old memory from the backup area of the first 640k area, which is done in the purgatory(). But, the current handling of copying the first 640k area runs into problems when SME is enabled, kernel does not properly copy these old memory to the backup area in the purgatory(), thereby, kdump kernel reads out the encrypted contents, because the kdump kernel must access the first kernel's memory with the encryption bit set when SME is enabled in the first kernel. Please refer to this link: Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=3D204793 Finally, it causes the following errors, and the crash tool gets invalid pointers when parsing the vmcore. crash> kmem -s|grep -i invalid kmem: dma-kmalloc-512: slab:ffffd77680001c00 invalid freepointer:a6086ac099= f0c5a4 kmem: dma-kmalloc-512: slab:ffffd77680001c00 invalid freepointer:a6086ac099= f0c5a4 crash> To avoid the above errors, when the crashkernel option is specified, lets reserve the remaining low 1MiB memory(after reserving real mode memory) so that the allocated memory does not fall into the low 1MiB area, which makes us not to copy the first 640k content to a backup region in purgatory(). This indicates that it does not need to be included in crash dumps or used for anything except the processor trampolines that must live in the low 1MiB. Signed-off-by: Lianbo Jiang --- arch/x86/include/asm/crash.h | 6 ++++++ arch/x86/kernel/crash.c | 15 +++++++++++++++ arch/x86/realmode/init.c | 2 ++ 3 files changed, 23 insertions(+) diff --git a/arch/x86/include/asm/crash.h b/arch/x86/include/asm/crash.h index 0acf5ee45a21..3e966a3dc823 100644 --- a/arch/x86/include/asm/crash.h +++ b/arch/x86/include/asm/crash.h @@ -8,4 +8,10 @@ int crash_setup_memmap_entries(struct kimage *image, =09=09struct boot_params *params); void crash_smp_send_stop(void); =20 +#ifdef CONFIG_KEXEC_CORE +void __init kexec_reserve_low_1MiB(void); +#else +static inline void __init kexec_reserve_low_1MiB(void) { } +#endif + #endif /* _ASM_X86_CRASH_H */ diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c index eb651fbde92a..144f519aef29 100644 --- a/arch/x86/kernel/crash.c +++ b/arch/x86/kernel/crash.c @@ -24,6 +24,7 @@ #include #include #include +#include =20 #include #include @@ -39,6 +40,7 @@ #include #include #include +#include =20 /* Used while preparing memory map entries for second kernel */ struct crash_memmap_data { @@ -68,6 +70,19 @@ static inline void cpu_crash_vmclear_loaded_vmcss(void) =09rcu_read_unlock(); } =20 +/* + * When the crashkernel option is specified, only use the low + * 1MiB for the real mode trampoline. + */ +void __init kexec_reserve_low_1MiB(void) +{ +=09if (cmdline_find_option(boot_command_line, "crashkernel", +=09=09=09=09NULL, 0) > 0) { +=09=09memblock_reserve(0, 1<<20); +=09=09pr_info("Reserving the low 1MiB of memory for crashkernel\n"); +=09} +} + #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC) =20 static void kdump_nmi_callback(int cpu, struct pt_regs *regs) diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c index 7dce39c8c034..b8bbd0017ca8 100644 --- a/arch/x86/realmode/init.c +++ b/arch/x86/realmode/init.c @@ -8,6 +8,7 @@ #include #include #include +#include =20 struct real_mode_header *real_mode_header; u32 *trampoline_cr4_features; @@ -34,6 +35,7 @@ void __init reserve_real_mode(void) =20 =09memblock_reserve(mem, size); =09set_real_mode_mem(mem); +=09kexec_reserve_low_1MiB(); } =20 static void __init setup_real_mode(void) --=20 2.17.1