Thomas Gleixner 07f07f55a2 x86/speculation/mds: Conditionally clear CPU buffers on idle entry ... Add a static key which controls the invocation of the CPU buffer clear mechanism on idle entry. This is independent of other MDS mitigations because the idle entry invocation to mitigate the potential leakage due to store buffer repartitioning is only necessary on SMT systems. Add the actual invocations to the different halt/mwait variants which covers all usage sites. mwaitx is not patched as it's not available on Intel CPUs. The buffer clear is only invoked before entering the C-State to prevent that stale data from the idling CPU is spilled to the Hyper-Thread sibling after the Store buffer got repartitioned and all entries are available to the non idle sibling. When coming out of idle the store buffer is partitioned again so each sibling has half of it available. Now CPU which returned from idle could be speculatively exposed to contents of the sibling, but the buffers are flushed either on exit to user space or on VMENTER. When later on conditional buffer clearing is implemented on top of this, then there is no action required either because before returning to user space the context switch will set the condition flag which causes a flush on the return to user path. Note, that the buffer clearing on idle is only sensible on CPUs which are solely affected by MSBDS and not any other variant of MDS because the other MDS variants cannot be mitigated when SMT is enabled, so the buffer clearing on idle would be a window dressing exercise. This intentionally does not handle the case in the acpi/processor_idle driver which uses the legacy IO port interface for C-State transitions for two reasons: - The acpi/processor_idle driver was replaced by the intel_idle driver almost a decade ago. Anything Nehalem upwards supports it and defaults to that new driver. - The legacy IO port interface is likely to be used on older and therefore unaffected CPUs or on systems which do not receive microcode updates anymore, so there is no point in adding that. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Borislav Petkov <bp@suse.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Reviewed-by: Jon Masters <jcm@redhat.com> Tested-by: Jon Masters <jcm@redhat.com>		2019-03-06 21:52:13 +01:00
..
ABI	Documentation/ABI: Correct mlxreg-io KernelVersion for 5.0	2019-01-26 11:30:26 -08:00
accelerators
accounting	psi: cgroup support	2018-10-26 16:26:32 -07:00
acpi	ACPI: property: graph: Update graph documentation to use generic references	2018-07-23 12:44:52 +02:00
admin-guide	A single patch from Arnd bringing some top-level docs into the 5.0 era.	2019-02-20 14:14:31 -08:00
aoe
arm	Documentation: Use "while" instead of "whilst"	2018-11-20 09:30:43 -07:00
arm64	arm64 festive updates for 4.21	2018-12-25 17:41:56 -08:00
auxdisplay
backlight
block	block: doc: add slice_idle_us to bfq documentation	2019-01-09 07:38:48 -07:00
blockdev	zram: idle writeback fixes and cleanup	2019-01-08 17:15:10 -08:00
bpf	bpf, doc: update design qa to reflect kern_version requirement	2019-01-07 15:52:00 -08:00
bus-devices
cdrom	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00
cgroup-v1	Merge branch 'for-4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup	2018-10-25 17:15:46 -07:00
cma
connector
console	Documentation: corrections to console/console.txt	2018-08-10 16:09:40 -06:00
core-api	XArray: Honour reserved entries in xa_insert	2019-01-06 22:12:58 -05:00
cpu-freq	Documentation: cpu-freq: Frequencies aren't always sorted	2018-11-07 13:29:04 +01:00
cpuidle	Documentation: admin-guide: PM: Add cpuidle document	2018-12-03 10:03:36 +01:00
crypto	crypto: skcipher - remove remnants of internal IV generators	2018-12-23 11:52:45 +08:00
dev-tools	A fairly normal cycle for documentation stuff. We have a new	2018-12-29 11:21:49 -08:00
device-mapper	Documentation: Use "while" instead of "whilst"	2018-11-20 09:30:43 -07:00
devicetree	A single fix for building DT bindings in-tree.	2019-02-02 10:34:32 -08:00
doc-guide	doc:process: add links where missing	2018-12-06 10:21:19 -07:00
driver-api	pci-v4.21-changes	2019-01-05 17:57:34 -08:00
driver-model	Documentation: driver core: remove use of BUS_ATTR	2019-01-08 15:17:45 +01:00
early-userspace	Correct gen_init_cpio tool's documentation	2018-11-25 12:25:53 -07:00
EDID	Docs/EDID: Calculate CRC while building the code	2018-11-06 07:36:22 -07:00
extcon
fault-injection
fb	fbdev: fbmem: convert CONFIG_FB_LOGO_CENTER into a cmd line option	2019-01-16 17:42:35 +01:00
features	Documentation/features: Add csky kernel features	2019-01-07 22:22:16 +08:00
filesystems	Documentation: driver core: remove use of BUS_ATTR	2019-01-08 15:17:45 +01:00
firmware_class
fmc	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00
fpga
gpio	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00
gpu	A fairly normal cycle for documentation stuff. We have a new	2018-12-29 11:21:49 -08:00
hid	HID: doc: fix wrong data structure reference for UHID_OUTPUT	2018-12-18 14:55:22 +01:00
hwmon	hwmon: Introduce SENSOR_DEVICE_ATTR_{RO, RW, WO} and variants	2018-12-16 15:13:22 -08:00
i2c	i2c: add i2c bus driver for NVIDIA GPU	2018-11-09 17:46:43 +01:00
ia64
ide	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00
iio
infiniband
input	Input: add REL_WHEEL_HI_RES and REL_HWHEEL_HI_RES	2018-12-07 16:27:11 +01:00
ioctl	seccomp: add a return code to trap to userspace	2018-12-11 16:28:41 -08:00
isdn	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00
kbuild	kbuild: generate asm-generic wrappers if mandatory headers are missing	2019-01-06 09:46:51 +09:00
kdump
kernel-hacking	doc:it_IT: translation for kernel-hacking	2018-07-26 16:21:09 -06:00
laptops	platform-drivers-x86 for v4.20-1	2018-11-01 08:42:21 -07:00
leds	Documentation: Use "while" instead of "whilst"	2018-11-20 09:30:43 -07:00
lightnvm
livepatch
locking	This is a fairly typical cycle for documentation. There's some welcome	2018-10-24 18:01:11 +01:00
m68k	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00
maintainer
md
media	A fairly normal cycle for documentation stuff. We have a new	2018-12-29 11:21:49 -08:00
memory-devices
mic
mips	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00
misc-devices	pci_endpoint_test: Add 2 ioctl commands	2018-07-19 11:46:57 +01:00
mmc	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00
mtd	Documentation: mtd: remove stale pxa3xx NAND controller documentation	2018-09-04 23:37:38 +02:00
namespaces
netlabel	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00
networking	net: dsa: Remove documentation for port_fdb_prepare	2019-02-23 18:38:00 -08:00
nfc
nios2
nvdimm	libnvdimm/security: Add documentation for nvdimm security support	2018-12-21 12:44:41 -08:00
nvmem	Documentation: nvmem: document cell tables and lookup entries	2018-09-28 15:14:54 +02:00
openrisc
parisc	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00
PCI	pci-v4.20-changes	2018-10-25 06:50:48 -07:00
pcmcia	pcmcia: remove long deprecated pcmcia_request_exclusive_irq() function	2018-08-18 12:30:42 -07:00
perf	Documentation: perf: Add documentation for ThunderX2 PMU uncore driver	2018-12-06 12:29:47 +00:00
phy
platform
power	Documentation: Use "while" instead of "whilst"	2018-11-20 09:30:43 -07:00
powerpc	powerpc/fadump: Reservationless firmware assisted dump	2018-12-21 11:32:49 +11:00
pps
process	Documentation: change linux-4.x references to 5.x	2019-02-17 15:41:05 -07:00
pti
ptp
rapidio
RCU	doc: Fix "struction" typo in RCU memory-ordering documentation	2018-11-12 08:56:25 -08:00
riscv
s390	Documentation: Use "while" instead of "whilst"	2018-11-20 09:30:43 -07:00
scheduler	This is a fairly typical cycle for documentation. There's some welcome	2018-10-24 18:01:11 +01:00
scsi	SCSI misc on 20181224	2018-12-28 14:48:06 -08:00
security	Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security	2019-01-02 09:43:14 -08:00
serial	Documentation: Use "while" instead of "whilst"	2018-11-20 09:30:43 -07:00
sh	sh: remove board_time_init() callback	2018-12-18 16:13:04 +01:00
sound	Documentation: Use "while" instead of "whilst"	2018-11-20 09:30:43 -07:00
sparc
sphinx
sphinx-static	docs: improve readability for people with poorer eyesight	2018-10-07 09:16:50 -06:00
spi	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00
sysctl	Documentation: Fix grammatical error in sysctl/fs.txt & clarify negative dentry	2019-02-11 09:10:22 -08:00
target
thermal	Documentation: Use "while" instead of "whilst"	2018-11-20 09:30:43 -07:00
timers	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00
trace	Merge branches 'pm-cpuidle', 'pm-cpufreq' and 'pm-sleep'	2019-01-11 10:09:51 +01:00
translations	Documentation: change linux-4.x references to 5.x	2019-02-17 15:41:05 -07:00
usb	Documentation/usb: Fix typo	2018-11-26 16:56:34 +01:00
userspace-api	Merge branch 'next-seccomp' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security	2019-01-02 09:48:13 -08:00
virtual	Documentation/virtual/kvm: Update URL for AMD SEV API specification	2019-01-11 18:38:07 +01:00
vm	A fairly normal cycle for documentation stuff. We have a new	2018-12-29 11:21:49 -08:00
w1	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00
watchdog	watchdog: docs: kernel-api: don't reference removed functions	2018-12-24 13:15:06 +01:00
wimax
x86	x86/speculation/mds: Conditionally clear CPU buffers on idle entry	2019-03-06 21:52:13 +01:00
xilinx	Documentation: xilinx: Add documentation for eemi APIs	2018-10-09 13:26:05 +02:00
xtensa
.gitignore
atomic_bitops.txt
atomic_t.txt
bt8xxgpio.txt
btmrvl.txt
bus-virt-phys-mapping.txt
Changes
clearing-warn-once.txt
CodingStyle
conf.py	This is a fairly typical cycle for documentation. There's some welcome	2018-10-24 18:01:11 +01:00
cpu-load.txt
cputopology.txt
crc32.txt
dcdbas.txt
debugging-modules.txt
debugging-via-ohci1394.txt
dell_rbu.txt
digsig.txt
DMA-API-HOWTO.txt
DMA-API.txt	dma-mapping: deprecate dma_zalloc_coherent	2018-12-20 08:14:09 +01:00
DMA-attributes.txt
DMA-ISA-LPC.txt
docutils.conf
dontdiff
efi-stub.txt	efi_stub: update documentation on dtb= parameter	2018-09-09 14:46:44 -06:00
eisa.txt
flexible-arrays.txt
futex-requeue-pi.txt
gcc-plugins.txt
highuid.txt
hw_random.txt
hwspinlock.txt
index.rst	x86/speculation/mds: Add mds_clear_cpu_buffers()	2019-03-06 21:52:12 +01:00
Intel-IOMMU.txt
intel_txt.txt
io-mapping.txt
io_ordering.txt
iostats.txt	block: Track DISCARD statistics and output them in stat and diskstat	2018-07-18 08:44:22 -06:00
IPMI.txt
IRQ-affinity.txt
IRQ-domain.txt
IRQ.txt
irqflags-tracing.txt
isa.txt
isapnp.txt
kernel-per-CPU-kthreads.txt	doc: Update removal of RCU-bh/sched update machinery	2018-08-30 10:59:48 -07:00
kobject.txt	kref/kobject: Improve documentation	2018-12-06 13:57:03 +01:00
kprobes.txt
kref.txt
ldm.txt
lockup-watchdogs.txt
logo.gif
logo.txt
lsm.txt
lzo.txt
mailbox.txt
Makefile	kbuild: Add support for DT binding schema checks	2018-12-13 09:41:32 -06:00
memory-barriers.txt	Documentation: Use "while" instead of "whilst"	2018-11-20 09:30:43 -07:00
men-chameleon-bus.txt
nommu-mmap.txt
ntb.txt
numastat.txt
padata.txt
parport-lowlevel.txt
percpu-rw-semaphore.txt
phy.txt
pi-futex.txt
pnp.txt
preempt-locking.txt	Documentation: preempt-locking: Use better example	2018-10-12 11:35:47 -06:00
pwm.txt
rbtree.txt
remoteproc.txt
rfkill.txt
robust-futex-ABI.txt
robust-futexes.txt
rpmsg.txt
rtc.txt
SAK.txt
sgi-ioc4.txt
siphash.txt
SM501.txt
smsc_ece1099.txt
speculation.txt
static-keys.txt	Documentation: Use "while" instead of "whilst"	2018-11-20 09:30:43 -07:00
SubmittingPatches
svga.txt
switchtec.txt	NTB: switchtec_ntb: Update switchtec documentation with prerequisites for NTB	2018-10-11 11:28:53 -05:00
sync_file.txt
tee.txt
this_cpu_ops.txt
unaligned-memory-access.txt
vfio-mediated-device.txt
vfio.txt
video-output.txt
xillybus.txt
xz.txt
zorro.txt