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ff4b353f2e
linux/arch/x86/kernel
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Fenghua Yu ff4b353f2e x86/umwait: Add sysfs interface to control umwait C0.2 state 
C0.2 state in umwait and tpause instructions can be enabled or disabled
on a processor through IA32_UMWAIT_CONTROL MSR register.

By default, C0.2 is enabled and the user wait instructions results in
lower power consumption with slower wakeup time.

But in real time systems which require faster wakeup time although power
savings could be smaller, the administrator needs to disable C0.2 and all
umwait invocations from user applications use C0.1.

Create a sysfs interface which allows the administrator to control C0.2
state during run time.

Andy Lutomirski suggested to turn off local irqs before writing the MSR to
ensure the cached control value is not changed by a concurrent sysfs write
from a different CPU via IPI.

[ tglx: Simplified the update logic in the write function and got rid of
  	all the convoluted type casts. Added a shared update function and
	made the namespace consistent. Moved the sysfs create invocation.
	Massaged changelog ]

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ashok Raj <ashok.raj@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
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: "Ravi V Shankar" <ravi.v.shankar@intel.com>
Link: https://lkml.kernel.org/r/1560994438-235698-4-git-send-email-fenghua.yu@intel.com
2019-06-24 01:44:20 +02:00
..
acpi x86/acpi/cstate: Add Zhaoxin processors support for cache flush policy in C3 2019-06-22 11:45:58 +02:00
apic treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 223 2019-05-30 11:29:55 -07:00
cpu x86/umwait: Add sysfs interface to control umwait C0.2 state 2019-06-24 01:44:20 +02:00
fpu treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
kprobes treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
.gitignore
alternative.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
amd_gart_64.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 213 2019-05-30 11:29:54 -07:00
amd_nb.c x86/amd_nb: Add PCI device IDs for family 17h, model 30h 2018-11-07 21:36:09 +01:00
apb_timer.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441 2019-06-05 17:37:17 +02:00
aperture_64.c x86/gart: Exclude GART aperture from kcore 2019-03-23 12:11:49 +01:00
apm_32.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 118 2019-05-24 17:39:02 +02:00
asm-offsets_32.c
asm-offsets_64.c x86/irq/64: Split the IRQ stack into its own pages 2019-04-17 15:37:02 +02:00
asm-offsets.c x86/kernel: Fix more -Wmissing-prototypes warnings 2018-12-08 12:24:35 +01:00
audit_64.c
bootflag.c
check.c x86/headers: Fix -Wmissing-prototypes warning 2018-11-23 07:59:59 +01:00
cpuid.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 142 2019-05-30 11:25:17 -07:00
crash_dump_32.c
crash_dump_64.c x86: Fix various typos in comments 2018-12-03 10:49:13 +01:00
crash.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
devicetree.c x86/headers: Fix -Wmissing-prototypes warning 2018-11-23 07:59:59 +01:00
doublefault.c
dumpstack_32.c x86/irq/32: Rename hard/softirq_stack to hard/softirq_stack_ptr 2019-04-17 15:24:18 +02:00
dumpstack_64.c x86/irq/64: Rename irq_stack_ptr to hardirq_stack_ptr 2019-04-17 15:27:10 +02:00
dumpstack.c x86/process: Don't mix user/kernel regs in 64bit __show_regs() 2018-09-06 14:33:12 +02:00
e820.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
early_printk.c efi/x86: Convert x86 EFI earlyprintk into generic earlycon implementation 2019-02-04 08:27:30 +01:00
early-quirks.c x86/gpu: add ElkhartLake to gen11 early quirks 2019-04-01 10:29:32 -07:00
ebda.c
eisa.c x86/EISA: Don't probe EISA bus for Xen PV guests 2018-09-11 23:36:50 +02:00
espfix_64.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 288 2019-06-05 17:36:37 +02:00
ftrace_32.S ftrace/x86: Remove mcount support 2019-05-10 12:33:09 -04:00
ftrace_64.S ftrace/x86: Remove mcount support 2019-05-10 12:33:09 -04:00
ftrace.c The major changes in this tracing update includes: 2019-05-15 16:05:47 -07:00
head32.c x86/boot: Mostly revert commit ae7e1238e6 ("Add ACPI RSDP address to setup_header") 2018-11-20 09:43:10 +01:00
head64.c x86/boot: Mostly revert commit ae7e1238e6 ("Add ACPI RSDP address to setup_header") 2018-11-20 09:43:10 +01:00
head_32.S
head_64.S x86/irq/64: Split the IRQ stack into its own pages 2019-04-17 15:37:02 +02:00
hpet.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
hw_breakpoint.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
i8237.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
i8253.c
i8259.c x86: Don't include linux/irq.h from asm/hardirq.h 2018-08-05 09:53:13 +02:00
idt.c x86/exceptions: Disconnect IST index and stack order 2019-04-17 15:01:09 +02:00
ima_arch.c x86/ima: Check EFI_RUNTIME_SERVICES before using 2019-05-19 20:27:12 -04:00
io_delay.c
ioport.c
irq_32.c x86/irq/32: Handle irq stack allocation failure proper 2019-04-17 15:31:42 +02:00
irq_64.c x86/irq/64: Remove stack overflow debug code 2019-04-17 15:41:48 +02:00
irq_work.c
irq.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
irqflags.S
irqinit.c x86/irq/32: Handle irq stack allocation failure proper 2019-04-17 15:31:42 +02:00
itmt.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441 2019-06-05 17:37:17 +02:00
jailhouse.c x86/headers: Fix -Wmissing-prototypes warning 2018-11-23 07:59:59 +01:00
jump_label.c x86/jump-label: Remove support for custom text poker 2019-04-30 12:37:55 +02:00
kdebugfs.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 428 2019-06-05 17:37:16 +02:00
kexec-bzimage64.c Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-03-10 17:32:04 -07:00
kgdb.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 118 2019-05-24 17:39:02 +02:00
ksysfs.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 428 2019-06-05 17:37:16 +02:00
kvm.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 19 2019-05-21 11:28:46 +02:00
kvmclock.c x86: kvmguest: use TSC clocksource if invariant TSC is exposed 2019-02-20 22:48:52 +01:00
ldt.c x86: Convert some slow-path static_cpu_has() callers to boot_cpu_has() 2019-04-08 12:13:34 +02:00
livepatch.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13 2019-05-21 11:28:45 +02:00
machine_kexec_32.c x86/kexec: Allocate 8k PGDs for PTI 2018-07-30 13:53:48 +02:00
machine_kexec_64.c x86/kdump: Export the SME mask to vmcoreinfo 2019-01-11 16:09:25 +01:00
Makefile treewide: prefix header search paths with $(srctree)/ 2019-05-18 11:49:57 +09:00
mmconf-fam10h_64.c
module.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
mpparse.c x86/mm: Don't leak kernel addresses 2019-03-19 12:10:56 +01:00
msr.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 142 2019-05-30 11:25:17 -07:00
nmi_selftest.c
nmi.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
paravirt_patch_32.c x86/paravirt: Remove unused _paravirt_ident_32 2018-10-30 09:55:31 +01:00
paravirt_patch_64.c x86/paravirt: Remove unused _paravirt_ident_32 2018-10-30 09:55:31 +01:00
paravirt-spinlocks.c x86/paravirt: Use a single ops structure 2018-09-03 16:50:35 +02:00
paravirt.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 102 2019-05-24 17:39:00 +02:00
pci-calgary_64.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
pci-dma.c x86/dma: Remove the x86_dma_fallback_dev hack 2019-04-08 17:52:46 +02:00
pci-iommu_table.c x86/iommu: Use NULL instead of 0 2018-08-02 14:33:19 +02:00
pci-swiotlb.c dma-direct: merge swiotlb_dma_ops into the dma_direct code 2018-12-13 21:06:17 +01:00
pcspeaker.c x86/platform/pcspeaker: Use PTR_ERR_OR_ZERO() to fix ptr_ret.cocci warning 2018-07-24 09:46:42 +02:00
perf_regs.c perf/x86: Support outputting XMM registers 2019-04-16 12:19:36 +02:00
platform-quirks.c
pmem.c
probe_roms.c
process_32.c Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-07 10:24:10 -07:00
process_64.c x86/process/64: Use FSGSBASE instructions on thread copy and ptrace 2019-06-22 11:38:53 +02:00
process.c Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-07 10:24:10 -07:00
process.h x86/speculation: Change misspelled STIPB to STIBP 2018-12-06 11:49:15 +01:00
ptrace.c x86/ptrace: Prevent ptrace from clearing the FS/GS selector 2019-06-22 11:38:50 +02:00
pvclock.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 102 2019-05-24 17:39:00 +02:00
quirks.c x86/headers: Fix -Wmissing-prototypes warning 2018-11-23 07:59:59 +01:00
reboot_fixups_32.c
reboot.c Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-06 15:32:35 -07:00
relocate_kernel_32.S
relocate_kernel_64.S
resource.c
rtc.c
setup_percpu.c x86/irq/64: Split the IRQ stack into its own pages 2019-04-17 15:37:02 +02:00
setup.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
signal_compat.c
signal.c Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-07 10:24:10 -07:00
smp.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 82 2019-05-24 17:37:52 +02:00
smpboot.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 82 2019-05-24 17:37:52 +02:00
stacktrace.c x86/stacktrace: Use common infrastructure 2019-04-29 12:37:57 +02:00
step.c
sys_x86_64.c x86/compat: Adjust in_compat_syscall() to generic code under !COMPAT 2018-11-01 12:59:25 +01:00
sysfb_efi.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
sysfb_simplefb.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
sysfb.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
tboot.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 335 2019-06-05 17:37:06 +02:00
tce_64.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
time.c Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-10-23 19:07:25 +01:00
tls.c
tls.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 193 2019-05-30 11:29:21 -07:00
topology.c x86/topology: Make DEBUG_HOTPLUG_CPU0 pr_info() more descriptive 2019-04-19 19:42:57 +02:00
trace_clock.c
tracepoint.c x86/kernel: Fix more -Wmissing-prototypes warnings 2018-12-08 12:24:35 +01:00
traps.c x86/speculation/mds: Revert CPU buffer clear on double fault exit 2019-05-16 09:05:11 +02:00
tsc_msr.c x86/cpu: Sanitize FAM6_ATOM naming 2018-10-02 10:14:32 +02:00
tsc_sync.c
tsc.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
umip.c signal/x86: Use force_sig_fault where appropriate 2018-09-21 15:30:54 +02:00
unwind_frame.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
unwind_guess.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
unwind_orc.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
uprobes.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
verify_cpu.S
vm86_32.c x86: Convert some slow-path static_cpu_has() callers to boot_cpu_has() 2019-04-08 12:13:34 +02:00
vmlinux.lds.S Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-06 16:13:31 -07:00
vsmp_64.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 346 2019-06-05 17:37:08 +02:00
x86_init.c x86/acpi, x86/boot: Take RSDP address for boot params if available 2018-10-10 10:44:22 +02:00