The maximum number of unique System V IPC identifiers was limited to
32k.  That limit should be big enough for most use cases.

However, there are some users out there requesting for more, especially
those that are migrating from Solaris which uses 24 bits for unique
identifiers.  To satisfy the need of those users, a new boot time kernel
option "ipcmni_extend" is added to extend the IPCMNI value to 16M.  This
is a 512X increase which should be big enough for users out there that
need a large number of unique IPC identifier.

The use of this new option will change the pattern of the IPC
identifiers returned by functions like shmget(2).  An application that
depends on such pattern may not work properly.  So it should only be
used if the users really need more than 32k of unique IPC numbers.

This new option does have the side effect of reducing the maximum number
of unique sequence numbers from 64k down to 128.  So it is a trade-off.

The computation of a new IPC id is not done in the performance critical
path.  So a little bit of additional overhead shouldn't have any real
performance impact.

Link: http://lkml.kernel.org/r/20190329204930.21620-1-longman@redhat.comSigned-off-by: NWaiman Long <longman@redhat.com>
Acked-by: NManfred Spraul <manfred@colorfullife.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Allow specifying reboot_mode for panic only.  This is needed on systems
where ramoops is used to store panic logs, and user wants to use warm
reset to preserve those, while still having cold reset on normal
reboots.

Link: http://lkml.kernel.org/r/20190322004735.27702-1-aaro.koskinen@iki.fiSigned-off-by: NAaro Koskinen <aaro.koskinen@nokia.com>
Reviewed-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Patch series "mm: Randomize free memory", v10.

This patch (of 3):

Randomization of the page allocator improves the average utilization of
a direct-mapped memory-side-cache.  Memory side caching is a platform
capability that Linux has been previously exposed to in HPC
(high-performance computing) environments on specialty platforms.  In
that instance it was a smaller pool of high-bandwidth-memory relative to
higher-capacity / lower-bandwidth DRAM.  Now, this capability is going
to be found on general purpose server platforms where DRAM is a cache in
front of higher latency persistent memory [1].

Robert offered an explanation of the state of the art of Linux
interactions with memory-side-caches [2], and I copy it here:

    It's been a problem in the HPC space:
    http://www.nersc.gov/research-and-development/knl-cache-mode-performance-coe/

    A kernel module called zonesort is available to try to help:
    https://software.intel.com/en-us/articles/xeon-phi-software

    and this abandoned patch series proposed that for the kernel:
    https://lkml.kernel.org/r/20170823100205.17311-1-lukasz.daniluk@intel.com

    Dan's patch series doesn't attempt to ensure buffers won't conflict, but
    also reduces the chance that the buffers will. This will make performance
    more consistent, albeit slower than "optimal" (which is near impossible
    to attain in a general-purpose kernel).  That's better than forcing
    users to deploy remedies like:
        "To eliminate this gradual degradation, we have added a Stream
         measurement to the Node Health Check that follows each job;
         nodes are rebooted whenever their measured memory bandwidth
         falls below 300 GB/s."

A replacement for zonesort was merged upstream in commit cc9aec03
("x86/numa_emulation: Introduce uniform split capability").  With this
numa_emulation capability, memory can be split into cache sized
("near-memory" sized) numa nodes.  A bind operation to such a node, and
disabling workloads on other nodes, enables full cache performance.
However, once the workload exceeds the cache size then cache conflicts
are unavoidable.  While HPC environments might be able to tolerate
time-scheduling of cache sized workloads, for general purpose server
platforms, the oversubscribed cache case will be the common case.

The worst case scenario is that a server system owner benchmarks a
workload at boot with an un-contended cache only to see that performance
degrade over time, even below the average cache performance due to
excessive conflicts.  Randomization clips the peaks and fills in the
valleys of cache utilization to yield steady average performance.

Here are some performance impact details of the patches:

1/ An Intel internal synthetic memory bandwidth measurement tool, saw a
   3X speedup in a contrived case that tries to force cache conflicts.
   The contrived cased used the numa_emulation capability to force an
   instance of the benchmark to be run in two of the near-memory sized
   numa nodes.  If both instances were placed on the same emulated they
   would fit and cause zero conflicts.  While on separate emulated nodes
   without randomization they underutilized the cache and conflicted
   unnecessarily due to the in-order allocation per node.

2/ A well known Java server application benchmark was run with a heap
   size that exceeded cache size by 3X.  The cache conflict rate was 8%
   for the first run and degraded to 21% after page allocator aging.  With
   randomization enabled the rate levelled out at 11%.

3/ A MongoDB workload did not observe measurable difference in
   cache-conflict rates, but the overall throughput dropped by 7% with
   randomization in one case.

4/ Mel Gorman ran his suite of performance workloads with randomization
   enabled on platforms without a memory-side-cache and saw a mix of some
   improvements and some losses [3].

While there is potentially significant improvement for applications that
depend on low latency access across a wide working-set, the performance
may be negligible to negative for other workloads.  For this reason the
shuffle capability defaults to off unless a direct-mapped
memory-side-cache is detected.  Even then, the page_alloc.shuffle=0
parameter can be specified to disable the randomization on those systems.

Outside of memory-side-cache utilization concerns there is potentially
security benefit from randomization.  Some data exfiltration and
return-oriented-programming attacks rely on the ability to infer the
location of sensitive data objects.  The kernel page allocator, especially
early in system boot, has predictable first-in-first out behavior for
physical pages.  Pages are freed in physical address order when first
onlined.

Quoting Kees:
    "While we already have a base-address randomization
     (CONFIG_RANDOMIZE_MEMORY), attacks against the same hardware and
     memory layouts would certainly be using the predictability of
     allocation ordering (i.e. for attacks where the base address isn't
     important: only the relative positions between allocated memory).
     This is common in lots of heap-style attacks. They try to gain
     control over ordering by spraying allocations, etc.

     I'd really like to see this because it gives us something similar
     to CONFIG_SLAB_FREELIST_RANDOM but for the page allocator."

While SLAB_FREELIST_RANDOM reduces the predictability of some local slab
caches it leaves vast bulk of memory to be predictably in order allocated.
However, it should be noted, the concrete security benefits are hard to
quantify, and no known CVE is mitigated by this randomization.

Introduce shuffle_free_memory(), and its helper shuffle_zone(), to perform
a Fisher-Yates shuffle of the page allocator 'free_area' lists when they
are initially populated with free memory at boot and at hotplug time.  Do
this based on either the presence of a page_alloc.shuffle=Y command line
parameter, or autodetection of a memory-side-cache (to be added in a
follow-on patch).

The shuffling is done in terms of CONFIG_SHUFFLE_PAGE_ORDER sized free
pages where the default CONFIG_SHUFFLE_PAGE_ORDER is MAX_ORDER-1 i.e.  10,
4MB this trades off randomization granularity for time spent shuffling.
MAX_ORDER-1 was chosen to be minimally invasive to the page allocator
while still showing memory-side cache behavior improvements, and the
expectation that the security implications of finer granularity
randomization is mitigated by CONFIG_SLAB_FREELIST_RANDOM.  The
performance impact of the shuffling appears to be in the noise compared to
other memory initialization work.

This initial randomization can be undone over time so a follow-on patch is
introduced to inject entropy on page free decisions.  It is reasonable to
ask if the page free entropy is sufficient, but it is not enough due to
the in-order initial freeing of pages.  At the start of that process
putting page1 in front or behind page0 still keeps them close together,
page2 is still near page1 and has a high chance of being adjacent.  As
more pages are added ordering diversity improves, but there is still high
page locality for the low address pages and this leads to no significant
impact to the cache conflict rate.

[1]: https://itpeernetwork.intel.com/intel-optane-dc-persistent-memory-operating-modes/
[2]: https://lkml.kernel.org/r/AT5PR8401MB1169D656C8B5E121752FC0F8AB120@AT5PR8401MB1169.NAMPRD84.PROD.OUTLOOK.COM
[3]: https://lkml.org/lkml/2018/10/12/309

[dan.j.williams@intel.com: fix shuffle enable]
  Link: http://lkml.kernel.org/r/154943713038.3858443.4125180191382062871.stgit@dwillia2-desk3.amr.corp.intel.com
[cai@lca.pw: fix SHUFFLE_PAGE_ALLOCATOR help texts]
  Link: http://lkml.kernel.org/r/20190425201300.75650-1-cai@lca.pw
Link: http://lkml.kernel.org/r/154899811738.3165233.12325692939590944259.stgit@dwillia2-desk3.amr.corp.intel.comSigned-off-by: NDan Williams <dan.j.williams@intel.com>
Signed-off-by: NQian Cai <cai@lca.pw>
Reviewed-by: NKees Cook <keescook@chromium.org>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Robert Elliott <elliott@hpe.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Configure arm64 runtime CPU speculation bug mitigations in accordance
with the 'mitigations=' cmdline option.  This affects Meltdown, Spectre
v2, and Speculative Store Bypass.

The default behavior is unchanged.
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
[will: reorder checks so KASLR implies KPTI and SSBS is affected by cmdline]
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Allow users to disable usage of MIO instructions by specifying pci=nomio
at the kernel command line.
Signed-off-by: NSebastian Ott <sebott@linux.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Provide a kernel parameter to force the usage of floating interrupts.
Signed-off-by: NSebastian Ott <sebott@linux.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

There are various reasons, such as benchmarking, to disable spectrev2
mitigation on a machine. Provide a command-line option to do so.
Signed-off-by: NJeremy Linton <jeremy.linton@arm.com>
Reviewed-by: NSuzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: NAndre Przywara <andre.przywara@arm.com>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Tested-by: NStefan Wahren <stefan.wahren@i2se.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Signed-off-by: NWill Deacon <will.deacon@arm.com>

crashkernel=xM tries to reserve memory for the crash kernel under 4G,
which is enough, usually. But this could fail sometimes, for example
when one tries to reserve a big chunk like 2G, for example.

So let the crashkernel=xM just fall back to use high memory in case it
fails to find a suitable low range. Do not set the ,high as default
because it allocates extra low memory for DMA buffers and swiotlb, and
this is not always necessary for all machines.

Typically, crashkernel=128M usually works with low reservation under 4G,
so keep <4G as default.

 [ bp: Massage. ]
Signed-off-by: NDave Young <dyoung@redhat.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NIngo Molnar <mingo@kernel.org>
Acked-by: NBaoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: linux-doc@vger.kernel.org
Cc: "Paul E. McKenney" <paulmck@linux.ibm.com>
Cc: Petr Tesarik <ptesarik@suse.cz>
Cc: piliu@redhat.com
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Sinan Kaya <okaya@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thymo van Beers <thymovanbeers@gmail.com>
Cc: vgoyal@redhat.com
Cc: x86-ml <x86@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Zhimin Gu <kookoo.gu@intel.com>
Link: https://lkml.kernel.org/r/20190422031905.GA8387@dhcp-128-65.nay.redhat.com

This patch implements a framework for Kernel Userspace Access
Protection.

Then subarches will have the possibility to provide their own
implementation by providing setup_kuap() and
allow/prevent_user_access().

Some platforms will need to know the area accessed and whether it is
accessed from read, write or both. Therefore source, destination and
size and handed over to the two functions.

mpe: Rename to allow/prevent rather than unlock/lock, and add
read/write wrappers. Drop the 32-bit code for now until we have an
implementation for it. Add kuap to pt_regs for 64-bit as well as
32-bit. Don't split strings, use pr_crit_ratelimited().
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: NRussell Currey <ruscur@russell.cc>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

This patch adds a skeleton for Kernel Userspace Execution Prevention.

Then subarches implementing it have to define CONFIG_PPC_HAVE_KUEP
and provide setup_kuep() function.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
[mpe: Don't split strings, use pr_crit_ratelimited()]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Add MDS to the new 'mitigations=' cmdline option.
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Configure s390 runtime CPU speculation bug mitigations in accordance
with the 'mitigations=' cmdline option.  This affects Spectre v1 and
Spectre v2.

The default behavior is unchanged.
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: Jiri Kosina <jkosina@suse.cz> (on x86)
Reviewed-by: NJiri Kosina <jkosina@suse.cz>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Jon Masters <jcm@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-arch@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Phil Auld <pauld@redhat.com>
Link: https://lkml.kernel.org/r/e4a161805458a5ec88812aac0307ae3908a030fc.1555085500.git.jpoimboe@redhat.com

Configure powerpc CPU runtime speculation bug mitigations in accordance
with the 'mitigations=' cmdline option.  This affects Meltdown, Spectre
v1, Spectre v2, and Speculative Store Bypass.

The default behavior is unchanged.
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: Jiri Kosina <jkosina@suse.cz> (on x86)
Reviewed-by: NJiri Kosina <jkosina@suse.cz>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Jon Masters <jcm@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-arch@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Phil Auld <pauld@redhat.com>
Link: https://lkml.kernel.org/r/245a606e1a42a558a310220312d9b6adb9159df6.1555085500.git.jpoimboe@redhat.com

Configure x86 runtime CPU speculation bug mitigations in accordance with
the 'mitigations=' cmdline option.  This affects Meltdown, Spectre v2,
Speculative Store Bypass, and L1TF.

The default behavior is unchanged.
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: Jiri Kosina <jkosina@suse.cz> (on x86)
Reviewed-by: NJiri Kosina <jkosina@suse.cz>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Jon Masters <jcm@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-arch@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Phil Auld <pauld@redhat.com>
Link: https://lkml.kernel.org/r/6616d0ae169308516cfdf5216bedd169f8a8291b.1555085500.git.jpoimboe@redhat.com

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: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: Jiri Kosina <jkosina@suse.cz> (on x86)
Reviewed-by: NJiri Kosina <jkosina@suse.cz>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Jon Masters <jcm@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-arch@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Phil Auld <pauld@redhat.com>
Link: https://lkml.kernel.org/r/b07a8ef9b7c5055c3a4637c87d07c296d5016fe0.1555085500.git.jpoimboe@redhat.com

Signed-off-by: NPetr Vorel <pvorel@suse.cz>
Signed-off-by: NMimi Zohar <zohar@linux.ibm.com>

Add the mds=full,nosmt cmdline option.  This is like mds=full, but with
SMT disabled if the CPU is vulnerable.
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NTyler Hicks <tyhicks@canonical.com>
Acked-by: NJiri Kosina <jkosina@suse.cz>

Currently, the rcu_nocbs= kernel boot parameter requires that a specific
list of CPUs be specified, and has no way to say "all of them".
As noted by user RavFX in a comment to Phoronix topic 1002538, this
is an inconvenient side effect of the removal of the RCU_NOCB_CPU_ALL
Kconfig option.  This commit therefore enables the rcu_nocbs= kernel boot
parameter to be given the string "all", as in "rcu_nocbs=all" to specify
that all CPUs on the system are to have their RCU callbacks offloaded.

Another approach would be to make cpulist_parse() check for "all", but
there are uses of cpulist_parse() that do other checking, which could
conflict with an "all".  This commit therefore focuses on the specific
use of cpulist_parse() in rcu_nocb_setup().

Just a note to other people who would like changes to Linux-kernel RCU:
If you send your requests to me directly, they might get fixed somewhat
faster.  RavFX's comment was posted on January 22, 2018 and I first saw
it on March 5, 2019.  And the only reason that I found it -at- -all- was
that I was looking for projects using RCU, and my search engine showed
me that Phoronix comment quite by accident.  Your choice, though!  ;-)
Signed-off-by: NPaul E. McKenney <paulmck@linux.ibm.com>

Clocksource watchdog has been found responsible for generating latency
spikes (in the 10-20 us range) when woken up to check for TSC stability.

Add an option to disable it at boot.
Signed-off-by: NJuri Lelli <juri.lelli@redhat.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: bigeasy@linutronix.de
Cc: linux-rt-users@vger.kernel.org
Cc: peterz@infradead.org
Cc: bristot@redhat.com
Cc: williams@redhat.com
Link: https://lkml.kernel.org/r/20190307120913.13168-1-juri.lelli@redhat.com

Add the initial MDS vulnerability documentation.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NJon Masters <jcm@redhat.com>

Move L!TF to a separate directory so the MDS stuff can be added at the
side. Otherwise the all hardware vulnerabilites have their own top level
entry. Should have done that right away.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: NJon Masters <jcm@redhat.com>

Now that the mitigations are in place, add a command line parameter to
control the mitigation, a mitigation selector function and a SMT update
mechanism.

This is the minimal straight forward initial implementation which just
provides an always on/off mode. The command line parameter is:

  mds=[full|off]

This is consistent with the existing mitigations for other speculative
hardware vulnerabilities.

The idle invocation is dynamically updated according to the SMT state of
the system similar to the dynamic update of the STIBP mitigation. The idle
mitigation is limited to CPUs which are only affected by MSBDS and not any
other variant, because the other variants cannot be mitigated on SMT
enabled systems.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NJon Masters <jcm@redhat.com>
Tested-by: NJon Masters <jcm@redhat.com>

To avoid potential confusion, explicitly ignore "security=" when "lsm=" is
used on the command line, and report that it is happening.
Suggested-by: NTetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: NKees Cook <keescook@chromium.org>
Acked-by: NCasey Schaufler <casey@schaufler-ca.com>
Acked-by: NJohn Johansen <john.johansen@canonical.com>
Signed-off-by: NJames Morris <james.morris@microsoft.com>

On Chrome OS we want to use USBguard to potentially limit access to USB
devices based on policy. We however to do not want to wait for userspace to
come up before initializing fixed USB devices to not regress our boot
times.

This patch adds option to instruct the kernel to only authorize devices
connected to the internal ports. Previously we could either authorize
all or none (or, by default, we'd only authorize wired devices).

The behavior is controlled via usbcore.authorized_default command line
option.
Signed-off-by: NDmitry Torokhov <dtor@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Asynchronous driver probing can help much on kernel fastboot, and
this option can provide a flexible way to optimize and quickly verify
async driver probe.

Also it will help in below cases:
* Some driver actually covers several families of HWs, some of which
  could use async probing while others don't. So we can't simply
  turn on the PROBE_PREFER_ASYNCHRONOUS flag in driver, but use this
  cmdline option, like igb driver async patch discussed at
  https://www.spinics.net/lists/netdev/msg545986.html

* For SOC (System on Chip) with multiple spi or i2c controllers, most
  of the slave spi/i2c devices will be assigned with fixed controller
  number, while async probing may make those controllers get different
  index for each boot, which prevents those controller drivers to be
  async probed. For platforms not using these spi/i2c slave devices,
  they can use this cmdline option to benefit from the async probing.
Suggested-by: NAlexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: NFeng Tang <feng.tang@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

For a while Arm64 has been capable of force enabling
or disabling the kpti mitigations. Lets make sure the
documentation reflects that.
Signed-off-by: NJeremy Linton <jeremy.linton@arm.com>
Reviewed-by: NAndre Przywara <andre.przywara@arm.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Legacy IO schedulers (cfq, deadline and noop) were removed in
f382fb0b.

The documentation for deadline was retained because it carries over to
mq-deadline as well, but location of the doc file was changed over time.

The old iosched algorithms were removed from elevator= kernel parameter
and mq-deadline, kyber and bfq were added with a reference to their
documentation.

Fixes: f382fb0b ("block: remove legacy IO schedulers")
Signed-off-by: NOtto Sabart <ottosabart@seberm.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Add a build option and a command line parameter to build and enable the
support of pseudo-NMIs.
Signed-off-by: NJulien Thierry <julien.thierry@arm.com>
Suggested-by: NDaniel Thompson <daniel.thompson@linaro.org>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Move the x86 EFI earlyprintk implementation to a shared location under
drivers/firmware and tweak it slightly so we can expose it as an earlycon
implementation (which is generic) rather than earlyprintk (which is only
implemented for a few architectures)

This also involves switching to write-combine mappings by default (which
is required on ARM since device mappings lack memory semantics, and so
memcpy/memset may not be used on them), and adding support for shared
memory framebuffers on cache coherent non-x86 systems (which do not
tolerate mismatched attributes).

Note that 32-bit ARM does not populate its struct screen_info early
enough for earlycon=efifb to work, so it is disabled there.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: NAlexander Graf <agraf@suse.de>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Jeffrey Hugo <jhugo@codeaurora.org>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Jones <pjones@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20190202094119.13230-10-ard.biesheuvel@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

commit 3fb72f1e ("ipconfig wait for carrier") added a
"wait for carrier" policy, with a fixed worst case maximum wait
of two minutes.

Now make the wait for carrier timeout configurable on the kernel
commandline and use the 120s as the default.

The timeout messages introduced with
commit 5e404cd6 ("ipconfig: add informative timeout messages while
waiting for carrier") are done in a fixed interval of 20 seconds, just
like they were before (240/12).
Signed-off-by: NMartin Kepplinger <martin.kepplinger@ginzinger.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Commit 765b6a98 ("iommu/vt-d: Enumerate the scalable
mode capability") enables VT-d scalable mode if hardware
advertises the capability. As we will bring up different
features and use cases to upstream in different patch
series, it will leave some intermediate kernel versions
which support partial features. Hence, end user might run
into problems when they use such kernels on bare metals
or virtualization environments.

This leaves scalable mode default off and end users could
turn it on with "intel-iommu=sm_on" only when they have
clear ideas about which scalable features are supported
in the kernel.

Cc: Liu Yi L <yi.l.liu@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Suggested-by: NAshok Raj <ashok.raj@intel.com>
Suggested-by: NKevin Tian <kevin.tian@intel.com>
Signed-off-by: NLu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: NJoerg Roedel <jroedel@suse.de>

The rcutree.jiffies_till_sched_qs kernel boot parameter used to solicit
help only from rcu_note_context_switch(), but now also solicits help
from cond_resched().  This commit therefore updates kernel-parameters.txt
accordingly.
Signed-off-by: NPaul E. McKenney <paulmck@linux.ibm.com>

Life is hard if RCU manages to get stuck without triggering RCU CPU
stall warnings or triggering the rcu_check_gp_start_stall() checks
for failing to start a grace period.  This commit therefore adds a
boot-time-selectable sysrq key (commandeering "y") that allows manually
dumping Tree RCU state.  The new rcutree.sysrq_rcu kernel boot parameter
must be set for this sysrq to be available.
Signed-off-by: NPaul E. McKenney <paulmck@linux.ibm.com>

Provide a way to explicitly choose LSM initialization order via the new
"lsm=" comma-separated list of LSMs.
Signed-off-by: NKees Cook <keescook@chromium.org>

Kernel panic issues are always painful to debug, partially because it's
not easy to get enough information of the context when panic happens.

And we have ramoops and kdump for that, while this commit tries to
provide a easier way to show the system info by adding a cmdline
parameter, referring some idea from sysrq handler.

Link: http://lkml.kernel.org/r/1543398842-19295-2-git-send-email-feng.tang@intel.comSigned-off-by: NFeng Tang <feng.tang@intel.com>
Reviewed-by: NKees Cook <keescook@chromium.org>
Acked-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add UART driver for RDA Micro RDA8810PL SoC.
Signed-off-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NOlof Johansson <olof@lixom.net>

It can be useful to inhibit all cgroup1 hierarchies especially during
transition and for debugging.  cgroup_no_v1 can block hierarchies with
controllers which leaves out the named hierarchies.  Expand it to
cover the named hierarchies so that "cgroup_no_v1=all,named" disables
all cgroup1 hierarchies.
Signed-off-by: NTejun Heo <tj@kernel.org>
Suggested-by: NMarcin Pawlowski <mpawlowski@fb.com>
Signed-off-by: NTejun Heo <tj@kernel.org>

Signed-off-by: NDiana Craciun <diana.craciun@nxp.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Add cpuidle.governor= command line parameter to allow the default
cpuidle governor to be replaced.

That is useful, for example, if someone running a tickful kernel
wants to use the menu governor on it.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Swap storage is restricted to max_swapfile_size (~16TB on x86_64) whenever
the system is deemed affected by L1TF vulnerability. Even though the limit
is quite high for most deployments it seems to be too restrictive for
deployments which are willing to live with the mitigation disabled.

We have a customer to deploy 8x 6,4TB PCIe/NVMe SSD swap devices which is
clearly out of the limit.

Drop the swap restriction when l1tf=off is specified. It also doesn't make
much sense to warn about too much memory for the l1tf mitigation when it is
forcefully disabled by the administrator.

[ tglx: Folded the documentation delta change ]

Fixes: 377eeaa8 ("x86/speculation/l1tf: Limit swap file size to MAX_PA/2")
Signed-off-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NPavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NJiri Kosina <jkosina@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: <linux-mm@kvack.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20181113184910.26697-1-mhocko@kernel.org