kernel.git/arch/x86/kernel/msr.c, branch linux-5.9.y

x86/msr: Filter MSR writes

2020-06-25T08:39:02Z

Add functionality to disable writing to MSRs from userspace. Writes can still be allowed by supplying the allow_writes=on module parameter. The kernel will be tainted so that it shows in oopses. Having unfettered access to all MSRs on a system is and has always been a disaster waiting to happen. Think performance counter MSRs, MSRs with sticky or locked bits, MSRs making major system changes like loading microcode, MTRRs, PAT configuration, TSC counter, security mitigations MSRs, you name it. This also destroys all the kernel's caching of MSR values for performance, as the recent case with MSR_AMD64_LS_CFG showed. Another example is writing MSRs by mistake by simply typing the wrong MSR address. System freezes have been experienced that way. In general, poking at MSRs under the kernel's feet is a bad bad idea. So log writing to MSRs by default. Longer term, such writes will be disabled by default. If userspace still wants to do that, then proper interfaces should be defined which are under the kernel's control and accesses to those MSRs can be synchronized and sanitized properly. [ Fix sparse warnings. ] Reported-by: kernel test robot Signed-off-by: Borislav Petkov Tested-by: Sean Christopherson Link: https://lkml.kernel.org/r/20200612105026.GA22660@zn.tnic

x86/msr: Restrict MSR access when the kernel is locked down

2019-08-20T04:54:16Z

Writing to MSRs should not be allowed if the kernel is locked down, since it could lead to execution of arbitrary code in kernel mode. Based on a patch by Kees Cook. Signed-off-by: Matthew Garrett Signed-off-by: David Howells Acked-by: Kees Cook Reviewed-by: Thomas Gleixner cc: x86@kernel.org Signed-off-by: James Morris

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 142

2019-05-30T18:25:17Z

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation inc 675 mass ave cambridge ma 02139 usa either version 2 of the license or at your option any later version incorporated herein by reference extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 4 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Richard Fontana Reviewed-by: Allison Randal Reviewed-by: Kate Stewart Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190524100844.465381181@linutronix.de Signed-off-by: Greg Kroah-Hartman

x86: Clean up 'sizeof x' => 'sizeof(x)'

2018-10-29T06:13:28Z

"sizeof(x)" is the canonical coding style used in arch/x86 most of the time. Fix the few places that didn't follow the convention. (Also do some whitespace cleanups in a few places while at it.) [ mingo: Rewrote the changelog. ] Signed-off-by: Jordan Borgner Cc: Borislav Petkov Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20181028125828.7rgammkgzep2wpam@JordanDesktop Signed-off-by: Ingo Molnar

x86/msr: Remove bogus cleanup from the error path

2016-12-25T09:47:41Z

The error cleanup which is invoked when the hotplug state setup failed tries to remove the failed state, which is broken. Fixes: 8fba38c937cd ("x86/msr: Convert to hotplug state machine") Reported-by: kernel test robot Signed-off-by: Thomas Gleixner Cc: Sebastian Siewior

x86/msr: Convert to hotplug state machine

2016-11-22T22:34:39Z

Install the callbacks via the state machine and let the core invoke the callbacks on the already online CPUs. Move the callbacks to online/offline as there is no point in having the files around before the cpu is online and until its completely gone. [ tglx: Move the callbacks to online/offline ] Signed-off-by: Sebastian Andrzej Siewior Cc: rt@linuxtronix.de Link: http://lkml.kernel.org/r/20161117183541.8588-4-bigeasy@linutronix.de Signed-off-by: Thomas Gleixner

x86/cpufeature: Carve out X86_FEATURE_*

2016-01-30T10:22:17Z

Move them to a separate header and have the following dependency: x86/cpufeatures.h <- x86/processor.h <- x86/cpufeature.h This makes it easier to use the header in asm code and not include the whole cpufeature.h and add guards for asm. Suggested-by: H. Peter Anvin Signed-off-by: Borislav Petkov Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1453842730-28463-5-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar

new helpers: no_seek_end_llseek{,_size}()

2015-12-23T15:41:31Z

Signed-off-by: Al Viro

x86, msr: Use seek definitions instead of hard-coded values

2014-10-17T20:40:55Z

Replace 0/1 by SEEK_SET/SEEK_CUR. Signed-off-by: Fabian Frederick Link: http://lkml.kernel.org/r/1413576120-27147-1-git-send-email-fabf@skynet.be Signed-off-by: H. Peter Anvin

x86, msr: Convert printk to pr_foo()

2014-10-17T20:40:54Z

Also define pr_fmt. Signed-off-by: Fabian Frederick Link: http://lkml.kernel.org/r/1413576110-27103-1-git-send-email-fabf@skynet.be Signed-off-by: H. Peter Anvin