linux.git/include/linux/cpu.h, branch v4.9.326

x86/speculation/mmio: Add sysfs reporting for Processor MMIO Stale Data

2022-06-16T11:00:52+00:00

commit 8d50cdf8b8341770bc6367bce40c0c1bb0e1d5b3 upstream

Add the sysfs reporting file for Processor MMIO Stale Data
vulnerability. It exposes the vulnerability and mitigation state similar
to the existing files for the other hardware vulnerabilities.

Signed-off-by: Pawan Gupta 
Signed-off-by: Borislav Petkov 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Thadeu Lima de Souza Cascardo 
Signed-off-by: Greg Kroah-Hartman

cpu/speculation: Add prototype for cpu_show_srbds()

2022-06-16T11:00:50+00:00

commit 2accfa69050c2a0d6fc6106f609208b3e9622b26 upstream.

0-day is not happy that there is no prototype for cpu_show_srbds():

drivers/base/cpu.c:565:16: error: no previous prototype for 'cpu_show_srbds'

Fixes: 7e5b3c267d25 ("x86/speculation: Add Special Register Buffer Data Sampling (SRBDS) mitigation")
Reported-by: kernel test robot 
Signed-off-by: Guenter Roeck 
Signed-off-by: Borislav Petkov 
Signed-off-by: Thomas Gleixner 
Link: https://lkml.kernel.org/r/20200617141410.93338-1-linux@roeck-us.net
Signed-off-by: Thadeu Lima de Souza Cascardo 
Signed-off-by: Greg Kroah-Hartman

cpu/speculation: Uninline and export CPU mitigations helpers

2019-11-16T09:29:54+00:00

commit 731dc9df975a5da21237a18c3384f811a7a41cc6 upstream.

A kernel module may need to check the value of the "mitigations=" kernel
command line parameter as part of its setup when the module needs
to perform software mitigations for a CPU flaw.

Uninline and export the helper functions surrounding the cpu_mitigations
enum to allow for their usage from a module.

Lastly, privatize the enum and cpu_mitigations variable since the value of
cpu_mitigations can be checked with the exported helper functions.

Signed-off-by: Tyler Hicks 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

x86/bugs: Add ITLB_MULTIHIT bug infrastructure

2019-11-16T09:29:54+00:00

commit db4d30fbb71b47e4ecb11c4efa5d8aad4b03dfae upstream.

Some processors may incur a machine check error possibly resulting in an
unrecoverable CPU lockup when an instruction fetch encounters a TLB
multi-hit in the instruction TLB. This can occur when the page size is
changed along with either the physical address or cache type. The relevant
erratum can be found here:

   https://bugzilla.kernel.org/show_bug.cgi?id=205195

There are other processors affected for which the erratum does not fully
disclose the impact.

This issue affects both bare-metal x86 page tables and EPT.

It can be mitigated by either eliminating the use of large pages or by
using careful TLB invalidations when changing the page size in the page
tables.

Just like Spectre, Meltdown, L1TF and MDS, a new bit has been allocated in
MSR_IA32_ARCH_CAPABILITIES (PSCHANGE_MC_NO) and will be set on CPUs which
are mitigated against this issue.

Signed-off-by: Vineela Tummalapalli 
Co-developed-by: Pawan Gupta 
Signed-off-by: Pawan Gupta 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Thomas Gleixner 
[bwh: Backported to 4.9:
 - No support for X86_VENDOR_HYGON, ATOM_AIRMONT_NP
 - Adjust context, indentation]
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

x86/speculation/taa: Add sysfs reporting for TSX Async Abort

2019-11-16T09:29:43+00:00

commit 6608b45ac5ecb56f9e171252229c39580cc85f0f upstream.

Add the sysfs reporting file for TSX Async Abort. It exposes the
vulnerability and the mitigation state similar to the existing files for
the other hardware vulnerabilities.

Sysfs file path is:
/sys/devices/system/cpu/vulnerabilities/tsx_async_abort

Signed-off-by: Pawan Gupta 
Signed-off-by: Borislav Petkov 
Signed-off-by: Thomas Gleixner 
Tested-by: Neelima Krishnan 
Reviewed-by: Mark Gross 
Reviewed-by: Tony Luck 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Josh Poimboeuf 
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

x86/power: Fix 'nosmt' vs hibernation triple fault during resume

2019-06-11T10:22:48+00:00

commit ec527c318036a65a083ef68d8ba95789d2212246 upstream.

As explained in

	0cc3cd21657b ("cpu/hotplug: Boot HT siblings at least once")

we always, no matter what, have to bring up x86 HT siblings during boot at
least once in order to avoid first MCE bringing the system to its knees.

That means that whenever 'nosmt' is supplied on the kernel command-line,
all the HT siblings are as a result sitting in mwait or cpudile after
going through the online-offline cycle at least once.

This causes a serious issue though when a kernel, which saw 'nosmt' on its
commandline, is going to perform resume from hibernation: if the resume
from the hibernated image is successful, cr3 is flipped in order to point
to the address space of the kernel that is being resumed, which in turn
means that all the HT siblings are all of a sudden mwaiting on address
which is no longer valid.

That results in triple fault shortly after cr3 is switched, and machine
reboots.

Fix this by always waking up all the SMT siblings before initiating the
'restore from hibernation' process; this guarantees that all the HT
siblings will be properly carried over to the resumed kernel waiting in
resume_play_dead(), and acted upon accordingly afterwards, based on the
target kernel configuration.

Symmetricaly, the resumed kernel has to push the SMT siblings to mwait
again in case it has SMT disabled; this means it has to online all
the siblings when resuming (so that they come out of hlt) and offline
them again to let them reach mwait.

Cc: 4.19+  # v4.19+
Debugged-by: Thomas Gleixner 
Fixes: 0cc3cd21657b ("cpu/hotplug: Boot HT siblings at least once")
Signed-off-by: Jiri Kosina 
Acked-by: Pavel Machek 
Reviewed-by: Thomas Gleixner 
Reviewed-by: Josh Poimboeuf 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman

cpu/speculation: Add 'mitigations=' cmdline option

2019-05-14T17:19:41+00:00

commit 98af8452945c55652de68536afdde3b520fec429 upstream.

Keeping track of the number of mitigations for all the CPU speculation
bugs has become overwhelming for many users.  It's getting more and more
complicated to decide which mitigations are needed for a given
architecture.  Complicating matters is the fact that each arch tends to
have its own custom way to mitigate the same vulnerability.

Most users fall into a few basic categories:

a) they want all mitigations off;

b) they want all reasonable mitigations on, with SMT enabled even if
   it's vulnerable; or

c) they want all reasonable mitigations on, with SMT disabled if
   vulnerable.

Define a set of curated, arch-independent options, each of which is an
aggregation of existing options:

- mitigations=off: Disable all mitigations.

- mitigations=auto: [default] Enable all the default mitigations, but
  leave SMT enabled, even if it's vulnerable.

- mitigations=auto,nosmt: Enable all the default mitigations, disabling
  SMT if needed by a mitigation.

Currently, these options are placeholders which don't actually do
anything.  They will be fleshed out in upcoming patches.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Thomas Gleixner 
Tested-by: Jiri Kosina  (on x86)
Reviewed-by: Jiri Kosina 
Cc: Borislav Petkov 
Cc: "H . Peter Anvin" 
Cc: Andy Lutomirski 
Cc: Peter Zijlstra 
Cc: Jiri Kosina 
Cc: Waiman Long 
Cc: Andrea Arcangeli 
Cc: Jon Masters 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Michael Ellerman 
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Cc: linux-s390@vger.kernel.org
Cc: Catalin Marinas 
Cc: Will Deacon 
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-arch@vger.kernel.org
Cc: Greg Kroah-Hartman 
Cc: Tyler Hicks 
Cc: Linus Torvalds 
Cc: Randy Dunlap 
Cc: Steven Price 
Cc: Phil Auld 
Link: https://lkml.kernel.org/r/b07a8ef9b7c5055c3a4637c87d07c296d5016fe0.1555085500.git.jpoimboe@redhat.com
[bwh: Backported to 4.9: adjust filename]
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

x86/speculation/mds: Add sysfs reporting for MDS

2019-05-14T17:19:40+00:00

commit 8a4b06d391b0a42a373808979b5028f5c84d9c6a upstream.

Add the sysfs reporting file for MDS. It exposes the vulnerability and
mitigation state similar to the existing files for the other speculative
hardware vulnerabilities.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Borislav Petkov 
Reviewed-by: Jon Masters 
Tested-by: Jon Masters 
[bwh: Backported to 4.9: test x86_hyper instead of using hypervisor_is_type()]
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

cpu/hotplug: Fix SMT supported evaluation

2018-08-15T16:14:53+00:00

commit bc2d8d262cba5736332cbc866acb11b1c5748aa9 upstream

Josh reported that the late SMT evaluation in cpu_smt_state_init() sets
cpu_smt_control to CPU_SMT_NOT_SUPPORTED in case that 'nosmt' was supplied
on the kernel command line as it cannot differentiate between SMT disabled
by BIOS and SMT soft disable via 'nosmt'. That wreckages the state and
makes the sysfs interface unusable.

Rework this so that during bringup of the non boot CPUs the availability of
SMT is determined in cpu_smt_allowed(). If a newly booted CPU is not a
'primary' thread then set the local cpu_smt_available marker and evaluate
this explicitely right after the initial SMP bringup has finished.

SMT evaulation on x86 is a trainwreck as the firmware has all the
information _before_ booting the kernel, but there is no interface to query
it.

Fixes: 73d5e2b47264 ("cpu/hotplug: detect SMT disabled by BIOS")
Reported-by: Josh Poimboeuf 
Signed-off-by: Thomas Gleixner 
Signed-off-by: David Woodhouse 
Signed-off-by: Greg Kroah-Hartman

cpu/hotplug: Set CPU_SMT_NOT_SUPPORTED early

2018-08-15T16:14:50+00:00

commit fee0aede6f4739c87179eca76136f83210953b86 upstream

The CPU_SMT_NOT_SUPPORTED state is set (if the processor does not support
SMT) when the sysfs SMT control file is initialized.

That was fine so far as this was only required to make the output of the
control file correct and to prevent writes in that case.

With the upcoming l1tf command line parameter, this needs to be set up
before the L1TF mitigation selection and command line parsing happens.

Signed-off-by: Thomas Gleixner 
Tested-by: Jiri Kosina 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Josh Poimboeuf 
Link: https://lkml.kernel.org/r/20180713142323.121795971@linutronix.de
Signed-off-by: David Woodhouse 
Signed-off-by: Greg Kroah-Hartman