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ASoC: More updates for v5.5

Some more development work for v5.5.  Highlights include:

 - More cleanups from Morimoto-san.
 - Trigger word detection for RT5677.

Signed-off-by: Takashi Iwai <[email protected]>
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tiwai committed Nov 25, 2019
2 parents c6b6fc2 + 8c4d2a0 commit 09578ea
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8 changes: 7 additions & 1 deletion .mailmap
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Expand Up @@ -108,6 +108,10 @@ Jason Gunthorpe <[email protected]> <[email protected]>
Jason Gunthorpe <[email protected]> <[email protected]>
Javi Merino <[email protected]> <[email protected]>
<[email protected]> <[email protected]>
Jayachandran C <[email protected]> <[email protected]>
Jayachandran C <[email protected]> <[email protected]>
Jayachandran C <[email protected]> <[email protected]>
Jayachandran C <[email protected]> <[email protected]>
Jean Tourrilhes <[email protected]>
<[email protected]> <[email protected]>
Jeff Garzik <[email protected]>
Expand Down Expand Up @@ -196,7 +200,8 @@ Oleksij Rempel <[email protected]> <[email protected]>
Oleksij Rempel <[email protected]> <[email protected]>
Paolo 'Blaisorblade' Giarrusso <[email protected]>
Patrick Mochel <[email protected]>
Paul Burton <[email protected]> <[email protected]>
Paul Burton <[email protected]> <[email protected]>
Paul Burton <[email protected]> <[email protected]>
Peter A Jonsson <[email protected]>
Peter Oruba <[email protected]>
Peter Oruba <[email protected]>
Expand Down Expand Up @@ -229,6 +234,7 @@ Shuah Khan <[email protected]> <[email protected]>
Shuah Khan <[email protected]> <[email protected]>
Shuah Khan <[email protected]> <[email protected]>
Shuah Khan <[email protected]> <[email protected]>
Simon Arlott <[email protected]> <[email protected]>
Simon Kelley <[email protected]>
Stéphane Witzmann <[email protected]>
Stephen Hemminger <[email protected]>
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4 changes: 4 additions & 0 deletions CREDITS
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Expand Up @@ -1637,6 +1637,10 @@ S: Panoramastrasse 18
S: D-69126 Heidelberg
S: Germany

N: Simon Horman
M: [email protected]
D: Renesas ARM/ARM64 SoC maintainer

N: Christopher Horn
E: [email protected]
D: Miscellaneous sysctl hacks
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2 changes: 2 additions & 0 deletions Documentation/ABI/testing/sysfs-devices-system-cpu
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Expand Up @@ -486,6 +486,8 @@ What: /sys/devices/system/cpu/vulnerabilities
/sys/devices/system/cpu/vulnerabilities/spec_store_bypass
/sys/devices/system/cpu/vulnerabilities/l1tf
/sys/devices/system/cpu/vulnerabilities/mds
/sys/devices/system/cpu/vulnerabilities/tsx_async_abort
/sys/devices/system/cpu/vulnerabilities/itlb_multihit
Date: January 2018
Contact: Linux kernel mailing list <[email protected]>
Description: Information about CPU vulnerabilities
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20 changes: 14 additions & 6 deletions Documentation/admin-guide/cgroup-v2.rst
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Expand Up @@ -615,8 +615,8 @@ on an IO device and is an example of this type.
Protections
-----------

A cgroup is protected to be allocated upto the configured amount of
the resource if the usages of all its ancestors are under their
A cgroup is protected upto the configured amount of the resource
as long as the usages of all its ancestors are under their
protected levels. Protections can be hard guarantees or best effort
soft boundaries. Protections can also be over-committed in which case
only upto the amount available to the parent is protected among
Expand Down Expand Up @@ -1096,7 +1096,10 @@ PAGE_SIZE multiple when read back.
is within its effective min boundary, the cgroup's memory
won't be reclaimed under any conditions. If there is no
unprotected reclaimable memory available, OOM killer
is invoked.
is invoked. Above the effective min boundary (or
effective low boundary if it is higher), pages are reclaimed
proportionally to the overage, reducing reclaim pressure for
smaller overages.

Effective min boundary is limited by memory.min values of
all ancestor cgroups. If there is memory.min overcommitment
Expand All @@ -1118,7 +1121,10 @@ PAGE_SIZE multiple when read back.
Best-effort memory protection. If the memory usage of a
cgroup is within its effective low boundary, the cgroup's
memory won't be reclaimed unless memory can be reclaimed
from unprotected cgroups.
from unprotected cgroups. Above the effective low boundary (or
effective min boundary if it is higher), pages are reclaimed
proportionally to the overage, reducing reclaim pressure for
smaller overages.

Effective low boundary is limited by memory.low values of
all ancestor cgroups. If there is memory.low overcommitment
Expand Down Expand Up @@ -2482,8 +2488,10 @@ system performance due to overreclaim, to the point where the feature
becomes self-defeating.

The memory.low boundary on the other hand is a top-down allocated
reserve. A cgroup enjoys reclaim protection when it's within its low,
which makes delegation of subtrees possible.
reserve. A cgroup enjoys reclaim protection when it's within its
effective low, which makes delegation of subtrees possible. It also
enjoys having reclaim pressure proportional to its overage when
above its effective low.

The original high boundary, the hard limit, is defined as a strict
limit that can not budge, even if the OOM killer has to be called.
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2 changes: 2 additions & 0 deletions Documentation/admin-guide/hw-vuln/index.rst
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Expand Up @@ -12,3 +12,5 @@ are configurable at compile, boot or run time.
spectre
l1tf
mds
tsx_async_abort
multihit.rst
163 changes: 163 additions & 0 deletions Documentation/admin-guide/hw-vuln/multihit.rst
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iTLB multihit
=============

iTLB multihit is an erratum where some processors may incur a machine check
error, possibly resulting in an unrecoverable CPU lockup, when an
instruction fetch hits multiple entries in the instruction TLB. This can
occur when the page size is changed along with either the physical address
or cache type. A malicious guest running on a virtualized system can
exploit this erratum to perform a denial of service attack.


Affected processors
-------------------

Variations of this erratum are present on most Intel Core and Xeon processor
models. The erratum is not present on:

- non-Intel processors

- Some Atoms (Airmont, Bonnell, Goldmont, GoldmontPlus, Saltwell, Silvermont)

- Intel processors that have the PSCHANGE_MC_NO bit set in the
IA32_ARCH_CAPABILITIES MSR.


Related CVEs
------------

The following CVE entry is related to this issue:

============== =================================================
CVE-2018-12207 Machine Check Error Avoidance on Page Size Change
============== =================================================


Problem
-------

Privileged software, including OS and virtual machine managers (VMM), are in
charge of memory management. A key component in memory management is the control
of the page tables. Modern processors use virtual memory, a technique that creates
the illusion of a very large memory for processors. This virtual space is split
into pages of a given size. Page tables translate virtual addresses to physical
addresses.

To reduce latency when performing a virtual to physical address translation,
processors include a structure, called TLB, that caches recent translations.
There are separate TLBs for instruction (iTLB) and data (dTLB).

Under this errata, instructions are fetched from a linear address translated
using a 4 KB translation cached in the iTLB. Privileged software modifies the
paging structure so that the same linear address using large page size (2 MB, 4
MB, 1 GB) with a different physical address or memory type. After the page
structure modification but before the software invalidates any iTLB entries for
the linear address, a code fetch that happens on the same linear address may
cause a machine-check error which can result in a system hang or shutdown.


Attack scenarios
----------------

Attacks against the iTLB multihit erratum can be mounted from malicious
guests in a virtualized system.


iTLB multihit system information
--------------------------------

The Linux kernel provides a sysfs interface to enumerate the current iTLB
multihit status of the system:whether the system is vulnerable and which
mitigations are active. The relevant sysfs file is:

/sys/devices/system/cpu/vulnerabilities/itlb_multihit

The possible values in this file are:

.. list-table::

* - Not affected
- The processor is not vulnerable.
* - KVM: Mitigation: Split huge pages
- Software changes mitigate this issue.
* - KVM: Vulnerable
- The processor is vulnerable, but no mitigation enabled


Enumeration of the erratum
--------------------------------

A new bit has been allocated in the IA32_ARCH_CAPABILITIES (PSCHANGE_MC_NO) msr
and will be set on CPU's which are mitigated against this issue.

======================================= =========== ===============================
IA32_ARCH_CAPABILITIES MSR Not present Possibly vulnerable,check model
IA32_ARCH_CAPABILITIES[PSCHANGE_MC_NO] '0' Likely vulnerable,check model
IA32_ARCH_CAPABILITIES[PSCHANGE_MC_NO] '1' Not vulnerable
======================================= =========== ===============================


Mitigation mechanism
-------------------------

This erratum can be mitigated by restricting the use of large page sizes to
non-executable pages. This forces all iTLB entries to be 4K, and removes
the possibility of multiple hits.

In order to mitigate the vulnerability, KVM initially marks all huge pages
as non-executable. If the guest attempts to execute in one of those pages,
the page is broken down into 4K pages, which are then marked executable.

If EPT is disabled or not available on the host, KVM is in control of TLB
flushes and the problematic situation cannot happen. However, the shadow
EPT paging mechanism used by nested virtualization is vulnerable, because
the nested guest can trigger multiple iTLB hits by modifying its own
(non-nested) page tables. For simplicity, KVM will make large pages
non-executable in all shadow paging modes.

Mitigation control on the kernel command line and KVM - module parameter
------------------------------------------------------------------------

The KVM hypervisor mitigation mechanism for marking huge pages as
non-executable can be controlled with a module parameter "nx_huge_pages=".
The kernel command line allows to control the iTLB multihit mitigations at
boot time with the option "kvm.nx_huge_pages=".

The valid arguments for these options are:

========== ================================================================
force Mitigation is enabled. In this case, the mitigation implements
non-executable huge pages in Linux kernel KVM module. All huge
pages in the EPT are marked as non-executable.
If a guest attempts to execute in one of those pages, the page is
broken down into 4K pages, which are then marked executable.

off Mitigation is disabled.

auto Enable mitigation only if the platform is affected and the kernel
was not booted with the "mitigations=off" command line parameter.
This is the default option.
========== ================================================================


Mitigation selection guide
--------------------------

1. No virtualization in use
^^^^^^^^^^^^^^^^^^^^^^^^^^^

The system is protected by the kernel unconditionally and no further
action is required.

2. Virtualization with trusted guests
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

If the guest comes from a trusted source, you may assume that the guest will
not attempt to maliciously exploit these errata and no further action is
required.

3. Virtualization with untrusted guests
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
If the guest comes from an untrusted source, the guest host kernel will need
to apply iTLB multihit mitigation via the kernel command line or kvm
module parameter.
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