From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:46411 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932306AbcHVO3m (ORCPT ); Mon, 22 Aug 2016 10:29:42 -0400 Subject: Patch "x86/platform/uv: Skip UV runtime services mapping in the efi_runtime_disabled case" has been added to the 4.7-stable tree To: athorlton@sgi.com, ard.biesheuvel@linaro.org, bp@alien8.de, bp@suse.de, brgerst@gmail.com, dvlasenk@redhat.com, gregkh@linuxfoundation.org, hpa@zytor.com, jpoimboe@redhat.com, luto@kernel.org, matt@codeblueprint.co.uk, mingo@kernel.org, peterz@infradead.org, rja@sgi.com, tglx@linutronix.de, torvalds@linux-foundation.org, travis@sgi.com Cc: , From: Date: Mon, 22 Aug 2016 10:29:45 -0400 Message-ID: <147187618586254@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled x86/platform/uv: Skip UV runtime services mapping in the efi_runtime_disabled case to the 4.7-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: x86-platform-uv-skip-uv-runtime-services-mapping-in-the-efi_runtime_disabled-case.patch and it can be found in the queue-4.7 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From f72075c9eda8a43aeea2f9dbb8d187afd4a76f0b Mon Sep 17 00:00:00 2001 From: Alex Thorlton Date: Thu, 11 Aug 2016 11:41:59 +0100 Subject: x86/platform/uv: Skip UV runtime services mapping in the efi_runtime_disabled case From: Alex Thorlton commit f72075c9eda8a43aeea2f9dbb8d187afd4a76f0b upstream. This problem has actually been in the UV code for a while, but we didn't catch it until recently, because we had been relying on EFI_OLD_MEMMAP to allow our systems to boot for a period of time. We noticed the issue when trying to kexec a recent community kernel, where we hit this NULL pointer dereference in efi_sync_low_kernel_mappings(): [ 0.337515] BUG: unable to handle kernel NULL pointer dereference at 0000000000000880 [ 0.346276] IP: [] efi_sync_low_kernel_mappings+0x5d/0x1b0 The problem doesn't show up with EFI_OLD_MEMMAP because we skip the chunk of setup_efi_state() that sets the efi_loader_signature for the kexec'd kernel. When the kexec'd kernel boots, it won't set EFI_BOOT in setup_arch, so we completely avoid the bug. We always kexec with noefi on the command line, so this shouldn't be an issue, but since we're not actually checking for efi_runtime_disabled in uv_bios_init(), we end up trying to do EFI runtime callbacks when we shouldn't be. This patch just adds a check for efi_runtime_disabled in uv_bios_init() so that we don't map in uv_systab when runtime_disabled == true. Signed-off-by: Alex Thorlton Signed-off-by: Matt Fleming Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: Borislav Petkov Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Mike Travis Cc: Peter Zijlstra Cc: Russ Anderson Cc: Thomas Gleixner Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1470912120-22831-2-git-send-email-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/platform/uv/bios_uv.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/arch/x86/platform/uv/bios_uv.c +++ b/arch/x86/platform/uv/bios_uv.c @@ -188,7 +188,8 @@ EXPORT_SYMBOL_GPL(uv_bios_set_legacy_vga void uv_bios_init(void) { uv_systab = NULL; - if ((efi.uv_systab == EFI_INVALID_TABLE_ADDR) || !efi.uv_systab) { + if ((efi.uv_systab == EFI_INVALID_TABLE_ADDR) || + !efi.uv_systab || efi_runtime_disabled()) { pr_crit("UV: UVsystab: missing\n"); return; } Patches currently in stable-queue which might be from athorlton@sgi.com are queue-4.7/x86-platform-uv-skip-uv-runtime-services-mapping-in-the-efi_runtime_disabled-case.patch