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linux/arch/x86/kernel
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Jiri Kosina d90a7a0ec8 x86/bugs, kvm: Introduce boot-time control of L1TF mitigations 
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 <jkosina@suse.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20180713142323.202758176@linutronix.de
2018-07-13 16:29:56 +02:00
..
acpi Revert "x86/apic: Ignore secondary threads if nosmt=force" 2018-07-02 11:25:28 +02:00
apic Revert "x86/apic: Ignore secondary threads if nosmt=force" 2018-07-02 11:25:28 +02:00
cpu x86/bugs, kvm: Introduce boot-time control of L1TF mitigations 2018-07-13 16:29:56 +02:00
fpu Merge commit 'upstream-x86-entry' into WIP.x86/mm 2017-12-17 12:58:53 +01:00
kprobes kprobes/x86: Prohibit probing on exception masking instructions 2018-05-13 19:52:55 +02:00
.gitignore
alternative.c x86/paravirt: Remove 'noreplace-paravirt' cmdline option 2018-01-31 10:37:45 +01:00
amd_gart_64.c x86/dma/amd_gart: Use dma_direct_{alloc,free}() 2018-03-20 10:01:57 +01:00
amd_nb.c x86/amd_nb: Add support for Raven Ridge CPUs 2018-05-13 09:00:27 -07:00
apb_timer.c
aperture_64.c x86/gart: Exclude GART aperture from vmcore 2018-01-11 15:09:24 +01:00
apm_32.c Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-06-04 19:17:47 -07:00
asm-offsets_32.c Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables 2018-06-14 12:21:18 +09:00
asm-offsets_64.c Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables 2018-06-14 12:21:18 +09:00
asm-offsets.c Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables 2018-06-14 12:21:18 +09:00
audit_64.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
bootflag.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
check.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
cpuid.c x86/cpuid: Allow cpuid_read() to schedule 2018-03-27 12:01:48 +02:00
crash_dump_32.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crash_dump_64.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crash.c kexec_file, x86: move re-factored code to generic side 2018-04-13 17:10:27 -07:00
devicetree.c Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-04-02 16:15:32 -07:00
doublefault.c x86/entry: Fix assumptions that the HW TSS is at the beginning of cpu_tss 2017-12-17 13:59:55 +01:00
dumpstack_32.c x86/dumpstack: Unify show_regs() 2018-03-08 12:04:59 +01:00
dumpstack_64.c x86/dumpstack: Unify show_regs() 2018-03-08 12:04:59 +01:00
dumpstack.c x86/dumpstack: Explain the reasoning for the prologue and buffer size 2018-04-26 16:15:28 +02:00
e820.c x86: Remove pr_fmt duplicate logging prefixes 2018-05-13 21:25:18 +02:00
early_printk.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
early-quirks.c x86/early-quirks: Rename duplicate define of dev_err 2018-05-13 20:04:35 +02:00
ebda.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
eisa.c
espfix_64.c x86/espfix: Document use of _PAGE_GLOBAL 2018-04-09 18:27:33 +02:00
ftrace_32.S x86/retpoline/ftrace: Convert ftrace assembler indirect jumps 2018-01-12 00:14:30 +01:00
ftrace_64.S Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-01-28 12:19:23 -08:00
ftrace.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
head32.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
head64.c x86/mm: Mark __pgtable_l5_enabled __initdata 2018-05-19 11:56:58 +02:00
head_32.S Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables 2018-06-14 12:21:18 +09:00
head_64.S x86/mm: Comment _PAGE_GLOBAL mystery 2018-04-12 09:05:58 +02:00
hpet.c treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
hw_breakpoint.c
i8237.c x86/i8237: Register device based on FADT legacy boot flag 2018-04-27 16:44:29 +02:00
i8253.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
i8259.c Merge branch 'linus' into x86/apic, to resolve conflicts 2017-11-07 10:51:10 +01:00
idt.c x86/idt: Simplify the idt_setup_apic_and_irq_gates() 2018-06-06 13:38:01 +02:00
io_delay.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ioport.c x86/ioport: add ksys_ioperm() helper; remove in-kernel calls to sys_ioperm() 2018-04-02 20:16:12 +02:00
irq_32.c x86/retpoline/irq32: Convert assembler indirect jumps 2018-01-12 00:14:32 +01:00
irq_64.c x86/irq/64: Print the offending IP in the stack overflow warning 2017-12-17 13:59:53 +01:00
irq_work.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
irq.c Drivers: hv: vmbus: Implement Direct Mode for stimer0 2018-03-06 09:57:17 -08:00
irqinit.c x86/apic: Simplify init_bsp_APIC() usage 2018-02-13 17:30:38 +01:00
itmt.c x86/headers: Remove duplicate #includes 2017-12-12 11:32:24 +01:00
jailhouse.c x86: Convert x86_platform_ops to timespec64 2018-05-19 14:03:14 +02:00
jump_label.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kdebugfs.c
kexec-bzimage64.c kexec_file: do not add extra alignment to efi memmap 2018-04-20 17:18:36 -07:00
kgdb.c
ksysfs.c treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
kvm.c kvm: rename KVM_HINTS_DEDICATED to KVM_HINTS_REALTIME 2018-05-17 19:12:13 +02:00
kvmclock.c x86: Convert x86_platform_ops to timespec64 2018-05-19 14:03:14 +02:00
ldt.c x86/ldt: Fix support_pte_mask filtering in map_ldt_struct() 2018-04-16 11:20:34 -07:00
livepatch.c
machine_kexec_32.c x86/kexec: Avoid double free_page() upon do_kexec_load() failure 2018-05-13 19:50:06 +02:00
machine_kexec_64.c x86/mm: Stop pretending pgtable_l5_enabled is a variable 2018-05-19 11:56:57 +02:00
Makefile Merge branch 'x86-dma-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-04-02 17:18:45 -07:00
mmconf-fam10h_64.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
module.c x86: Treat R_X86_64_PLT32 as R_X86_64_PC32 2018-02-22 09:01:10 -08:00
mpparse.c Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-02-14 17:02:15 -08:00
msr.c
nmi_selftest.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
nmi.c locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE() 2017-10-25 11:01:08 +02:00
paravirt_patch_32.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
paravirt_patch_64.c x86/paravirt: Dont patch flush_tlb_single 2017-12-17 14:27:52 +01:00
paravirt-spinlocks.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
paravirt.c x86/mm: Rename flush_tlb_single() and flush_tlb_one() to __flush_tlb_one_[user|kernel]() 2018-02-15 01:15:52 +01:00
pci-calgary_64.c x86/dma: Remove dma_alloc_coherent_gfp_flags() 2018-03-20 10:01:58 +01:00
pci-dma.c x86/pci-dma: switch the VIA 32-bit DMA quirk to use the struct device flag 2018-05-28 12:48:25 +02:00
pci-iommu_table.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pci-swiotlb.c x86/dma: Use generic swiotlb_ops 2018-03-20 10:01:57 +01:00
pcspeaker.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
perf_regs.c perf/x86: Store user space frame-pointer value on a sample 2018-05-25 08:11:12 +02:00
platform-quirks.c x86/i8237: Register device based on FADT legacy boot flag 2018-04-27 16:44:29 +02:00
pmem.c resource: Provide resource struct in resource walk callback 2017-11-07 15:35:57 +01:00
probe_roms.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
process_32.c x86/dumpstack: Add a show_ip() function 2018-04-26 16:15:27 +02:00
process_64.c x86/mm: Drop TS_COMPAT on 64-bit exec() syscall 2018-05-19 12:31:05 +02:00
process.c x86/speculation: Rework speculative_store_bypass_update() 2018-05-17 17:09:19 +02:00
ptrace.c signal: Ensure every siginfo we send has all bits initialized 2018-04-25 10:40:51 -05:00
pvclock.c x86: Convert x86_platform_ops to timespec64 2018-05-19 14:03:14 +02:00
quirks.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
reboot_fixups_32.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
reboot.c x86/apic: Fix restoring boot IRQ mode in reboot and kexec/kdump 2018-02-17 11:47:45 +01:00
relocate_kernel_32.S
relocate_kernel_64.S x86/kexec: Make kexec (mostly) work in 5-level paging mode 2018-01-31 08:39:40 +01:00
resource.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
rtc.c x86: Convert x86_platform_ops to timespec64 2018-05-19 14:03:14 +02:00
setup_percpu.c x86/cpu_entry_area: Sync cpu_entry_area to initial_page_table 2018-03-01 09:48:27 +01:00
setup.c x86/speculation/l1tf: Make sure the first page is always reserved 2018-06-20 19:10:00 +02:00
signal_compat.c signal: Add TRAP_UNK si_code for undiagnosted trap exceptions 2018-04-25 10:40:56 -05:00
signal.c x86: Add support for restartable sequences 2018-06-06 11:58:32 +02:00
smp.c
smpboot.c x86/topology: Provide topology_smt_supported() 2018-06-21 14:20:57 +02:00
stacktrace.c Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-01-03 16:41:07 -08:00
step.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sys_x86_64.c compat: Move compat_timespec/ timeval to compat_time.h 2018-04-19 13:29:54 +02:00
sysfb_efi.c
sysfb_simplefb.c
sysfb.c
tboot.c x86/pti: Make unpoison of pgd for trusted boot work for real 2018-01-11 23:36:59 +01:00
tce_64.c
time.c x86/time: Unconditionally register legacy timer interrupt 2018-01-14 20:18:23 +01:00
tls.c x86/ldt: Make the LDT mapping RO 2017-12-23 21:13:01 +01:00
tls.h
topology.c
trace_clock.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
tracepoint.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
traps.c signal: Ensure every siginfo we send has all bits initialized 2018-04-25 10:40:51 -05:00
tsc_msr.c
tsc_sync.c Merge branch 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-13 19:07:38 -08:00
tsc.c x86/tsc: Fix mark_tsc_unstable() 2018-05-02 16:10:40 +02:00
umip.c signal: Ensure every siginfo we send has all bits initialized 2018-04-25 10:40:51 -05:00
unwind_frame.c x86/unwind: Disable unwinder warnings on 32-bit 2017-10-10 12:49:49 +02:00
unwind_guess.c
unwind_orc.c extable: Make init_kernel_text() global 2018-02-21 16:54:06 +01:00
uprobes.c Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-06-04 19:17:47 -07:00
verify_cpu.S
vm86_32.c x86/vm86/32: Fix POPF emulation 2018-03-14 09:21:01 +01:00
vmlinux.lds.S x86/build: Remove no-op macro VMLINUX_SYMBOL() 2018-05-13 15:11:34 +02:00
vsmp_64.c
x86_init.c xen, mm: allow deferred page initialization for xen pv domains 2018-04-11 10:28:38 -07:00