linux.git/Documentation/ABI/testing, branch v4.9.158

x86/bugs, kvm: Introduce boot-time control of L1TF mitigations

2018-08-15T16:14:51+00:00

commit d90a7a0ec83fb86622cd7dae23255d3c50a99ec8 upstream

Introduce the 'l1tf=' kernel command line option to allow for boot-time
switching of mitigation that is used on processors affected by L1TF.

The possible values are:

  full
	Provides all available mitigations for the L1TF vulnerability. Disables
	SMT and enables all mitigations in the hypervisors. SMT control via
	/sys/devices/system/cpu/smt/control is still possible after boot.
	Hypervisors will issue a warning when the first VM is started in
	a potentially insecure configuration, i.e. SMT enabled or L1D flush
	disabled.

  full,force
	Same as 'full', but disables SMT control. Implies the 'nosmt=force'
	command line option. sysfs control of SMT and the hypervisor flush
	control is disabled.

  flush
	Leaves SMT enabled and enables the conditional hypervisor mitigation.
	Hypervisors will issue a warning when the first VM is started in a
	potentially insecure configuration, i.e. SMT enabled or L1D flush
	disabled.

  flush,nosmt
	Disables SMT and enables the conditional hypervisor mitigation. SMT
	control via /sys/devices/system/cpu/smt/control is still possible
	after boot. If SMT is reenabled or flushing disabled at runtime
	hypervisors will issue a warning.

  flush,nowarn
	Same as 'flush', but hypervisors will not warn when
	a VM is started in a potentially insecure configuration.

  off
	Disables hypervisor mitigations and doesn't emit any warnings.

Default is 'flush'.

Let KVM adhere to these semantics, which means:

  - 'lt1f=full,force'	: Performe L1D flushes. No runtime control
    			  possible.

  - 'l1tf=full'
  - 'l1tf-flush'
  - 'l1tf=flush,nosmt'	: Perform L1D flushes and warn on VM start if
			  SMT has been runtime enabled or L1D flushing
			  has been run-time enabled

  - 'l1tf=flush,nowarn'	: Perform L1D flushes and no warnings are emitted.

  - 'l1tf=off'		: L1D flushes are not performed and no warnings
			  are emitted.

KVM can always override the L1D flushing behavior using its 'vmentry_l1d_flush'
module parameter except when lt1f=full,force is set.

This makes KVM's private 'nosmt' option redundant, and as it is a bit
non-systematic anyway (this is something to control globally, not on
hypervisor level), remove that option.

Add the missing Documentation entry for the l1tf vulnerability sysfs file
while at it.

Signed-off-by: Jiri Kosina 
Signed-off-by: Thomas Gleixner 
Tested-by: Jiri Kosina 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Josh Poimboeuf 
Link: https://lkml.kernel.org/r/20180713142323.202758176@linutronix.de
Signed-off-by: David Woodhouse 
Signed-off-by: Greg Kroah-Hartman

cpu/hotplug: Provide knobs to control SMT

2018-08-15T16:14:46+00:00

commit 05736e4ac13c08a4a9b1ef2de26dd31a32cbee57 upstream

Provide a command line and a sysfs knob to control SMT.

The command line options are:

 'nosmt':	Enumerate secondary threads, but do not online them

 'nosmt=force': Ignore secondary threads completely during enumeration
 		via MP table and ACPI/MADT.

The sysfs control file has the following states (read/write):

 'on':		 SMT is enabled. Secondary threads can be freely onlined
 'off':		 SMT is disabled. Secondary threads, even if enumerated
 		 cannot be onlined
 'forceoff':	 SMT is permanentely disabled. Writes to the control
 		 file are rejected.
 'notsupported': SMT is not supported by the CPU

The command line option 'nosmt' sets the sysfs control to 'off'. This
can be changed to 'on' to reenable SMT during runtime.

The command line option 'nosmt=force' sets the sysfs control to
'forceoff'. This cannot be changed during runtime.

When SMT is 'on' and the control file is changed to 'off' then all online
secondary threads are offlined and attempts to online a secondary thread
later on are rejected.

When SMT is 'off' and the control file is changed to 'on' then secondary
threads can be onlined again. The 'off' -> 'on' transition does not
automatically online the secondary threads.

When the control file is set to 'forceoff', the behaviour is the same as
setting it to 'off', but the operation is irreversible and later writes to
the control file are rejected.

When the control status is 'notsupported' then writes to the control file
are rejected.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Konrad Rzeszutek Wilk 
Acked-by: Ingo Molnar 
Signed-off-by: David Woodhouse 
Signed-off-by: Greg Kroah-Hartman

x86/bugs: Expose /sys/../spec_store_bypass

2018-05-22T14:57:59+00:00

commit c456442cd3a59eeb1d60293c26cbe2ff2c4e42cf upstream

Add the sysfs file for the new vulerability. It does not do much except
show the words 'Vulnerable' for recent x86 cores.

Intel cores prior to family 6 are known not to be vulnerable, and so are
some Atoms and some Xeon Phi.

It assumes that older Cyrix, Centaur, etc. cores are immune.

Signed-off-by: Konrad Rzeszutek Wilk 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Borislav Petkov 
Reviewed-by: Ingo Molnar 
Signed-off-by: David Woodhouse 
Signed-off-by: Greg Kroah-Hartman

iio: ABI: Fix name of timestamp sysfs file

2018-03-28T16:39:25+00:00

commit b9a3589332c2a25fb7edad25a26fcaada3209126 upstream.

The name of the file is "current_timetamp_clock" not
"timestamp_clock".

Fixes: bc2b7dab629a ("iio:core: timestamping clock selection support")
Cc: Gregor Boirie 
Signed-off-by: Linus Walleij 
Signed-off-by: Jonathan Cameron 
Signed-off-by: Greg Kroah-Hartman

sysfs/cpu: Fix typos in vulnerability documentation

2018-01-17T08:38:58+00:00

commit 9ecccfaa7cb5249bd31bdceb93fcf5bedb8a24d8 upstream.

Fixes: 87590ce6e ("sysfs/cpu: Add vulnerability folder")
Signed-off-by: David Woodhouse 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

sysfs/cpu: Add vulnerability folder

2018-01-17T08:38:57+00:00

commit 87590ce6e373d1a5401f6539f0c59ef92dd924a9 upstream.

As the meltdown/spectre problem affects several CPU architectures, it makes
sense to have common way to express whether a system is affected by a
particular vulnerability or not. If affected the way to express the
mitigation should be common as well.

Create /sys/devices/system/cpu/vulnerabilities folder and files for
meltdown, spectre_v1 and spectre_v2.

Allow architectures to override the show function.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Konrad Rzeszutek Wilk 
Cc: Peter Zijlstra 
Cc: Will Deacon 
Cc: Dave Hansen 
Cc: Linus Torvalds 
Cc: Borislav Petkov 
Cc: David Woodhouse 
Link: https://lkml.kernel.org/r/20180107214913.096657732@linutronix.de
Signed-off-by: Greg Kroah-Hartman

Merge tag 'platform-drivers-x86-v4.9-3' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86

2016-11-12T00:48:49+00:00

Pull x86 platform driver fixes from Darren Hart:
 "Minor doc fix, a DMI match for ideapad and a fix to toshiba-wmi to
  avoid loading on non-toshiba systems.

  Documentation/ABI:
   - ibm_rtl: The "What:" fields are incomplete

  toshiba-wmi:
   - Fix loading the driver on non Toshiba laptops

  ideapad-laptop:
   - Add another DMI entry for Yoga 900"

* tag 'platform-drivers-x86-v4.9-3' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86:
  Documentation/ABI: ibm_rtl: The "What:" fields are incomplete
  toshiba-wmi: Fix loading the driver on non Toshiba laptops
  ideapad-laptop: Add another DMI entry for Yoga 900

Documentation/ABI: ibm_rtl: The "What:" fields are incomplete

2016-11-01T16:27:33+00:00

The "What:" field at the ABI should describe the location of
the ABI, e. g. the position under a mounted sysfs. However,
this file has only the basename without the path.

Fix it.

Cc: Vernon Mauery 
Cc: platform-driver-x86@vger.kernel.org
Signed-off-by: Mauro Carvalho Chehab 
Signed-off-by: Darren Hart

cxl: Prevent adapter reset if an active context exists

2016-10-19T09:35:39+00:00

This patch prevents resetting the cxl adapter via sysfs in presence of
one or more active cxl_context on it. This protects against an
unrecoverable error caused by PSL owning a dirty cache line even after
reset and host tries to touch the same cache line. In case a force reset
of the card is required irrespective of any active contexts, the int
value -1 can be stored in the 'reset' sysfs attribute of the card.

The patch introduces a new atomic_t member named contexts_num inside
struct cxl that holds the number of active context attached to the card
, which is checked against '0' before proceeding with the reset. To
prevent against a race condition where a context is activated just after
reset check is performed, the contexts_num is atomically set to '-1'
after reset-check to indicate that no more contexts can be activated on
the card anymore.

Before activating a context we atomically test if contexts_num is
non-negative and if so, increment its value by one. In case the value of
contexts_num is negative then it indicates that the card is about to be
reset and context activation is error-ed out at that point.

Fixes: 62fa19d4b4fd ("cxl: Add ability to reset the card")
Cc: stable@vger.kernel.org # v4.0+
Acked-by: Frederic Barrat 
Reviewed-by: Andrew Donnellan 
Signed-off-by: Vaibhav Jain 
Signed-off-by: Michael Ellerman

Merge tag 'ceph-for-4.9-rc1' of git://github.com/ceph/ceph-client

2016-10-10T20:52:05+00:00

Pull Ceph updates from Ilya Dryomov:
 "The big ticket item here is support for rbd exclusive-lock feature,
  with maintenance operations offloaded to userspace (Douglas Fuller,
  Mike Christie and myself). Another block device bullet is a series
  fixing up layering error paths (myself).

  On the filesystem side, we've got patches that improve our handling of
  buffered vs dio write races (Neil Brown) and a few assorted fixes from
  Zheng. Also included a couple of random cleanups and a minor CRUSH
  update"

* tag 'ceph-for-4.9-rc1' of git://github.com/ceph/ceph-client: (39 commits)
  crush: remove redundant local variable
  crush: don't normalize input of crush_ln iteratively
  libceph: ceph_build_auth() doesn't need ceph_auth_build_hello()
  libceph: use CEPH_AUTH_UNKNOWN in ceph_auth_build_hello()
  ceph: fix description for rsize and rasize mount options
  rbd: use kmalloc_array() in rbd_header_from_disk()
  ceph: use list_move instead of list_del/list_add
  ceph: handle CEPH_SESSION_REJECT message
  ceph: avoid accessing / when mounting a subpath
  ceph: fix mandatory flock check
  ceph: remove warning when ceph_releasepage() is called on dirty page
  ceph: ignore error from invalidate_inode_pages2_range() in direct write
  ceph: fix error handling of start_read()
  rbd: add rbd_obj_request_error() helper
  rbd: img_data requests don't own their page array
  rbd: don't call rbd_osd_req_format_read() for !img_data requests
  rbd: rework rbd_img_obj_exists_submit() error paths
  rbd: don't crash or leak on errors in rbd_img_obj_parent_read_full_callback()
  rbd: move bumping img_request refcount into rbd_obj_request_submit()
  rbd: mark the original request as done if stat request fails
  ...