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x86: disable usermode on 64-bit unless no meltdown

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KPTI is still work-in-progress on x86_64. Don't allow
user mode to be enabled unless the SOC/board configuration
indicates that the CPU in use is invulnerable to meltdown
attacks.

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
This commit is contained in:
Andrew Boie 2020-01-05 17:19:43 -08:00 • committed by Anas Nashif
commit 808cca0efb
2 changed files with 4 additions and 3 deletions
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6
arch/x86/Kconfig
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@ -17,14 +17,14 @@ config CPU_ATOM
bool bool
select CPU_HAS_FPU select CPU_HAS_FPU
select ARCH_HAS_STACK_PROTECTION if X86_MMU select ARCH_HAS_STACK_PROTECTION if X86_MMU
select ARCH_HAS_USERSPACE if X86_MMU select ARCH_HAS_USERSPACE if X86_MMU && (!X86_64 || (X86_64 && X86_NO_MELTDOWN))
help help
This option signifies the use of a CPU from the Atom family. This option signifies the use of a CPU from the Atom family.
config CPU_MINUTEIA config CPU_MINUTEIA
bool bool
select ARCH_HAS_STACK_PROTECTION if X86_MMU select ARCH_HAS_STACK_PROTECTION if X86_MMU
select ARCH_HAS_USERSPACE if X86_MMU select ARCH_HAS_USERSPACE if X86_MMU && (!X86_64 || (X86_64 && X86_NO_MELTDOWN))
help help
This option signifies the use of a CPU from the Minute IA family. This option signifies the use of a CPU from the Minute IA family.
@ -32,7 +32,7 @@ config CPU_APOLLO_LAKE
bool bool
select CPU_HAS_FPU select CPU_HAS_FPU
select ARCH_HAS_STACK_PROTECTION if X86_MMU select ARCH_HAS_STACK_PROTECTION if X86_MMU
select ARCH_HAS_USERSPACE if X86_MMU select ARCH_HAS_USERSPACE if X86_MMU && (!X86_64 || (X86_64 && X86_NO_MELTDOWN))
help help
This option signifies the use of a CPU from the Apollo Lake family. This option signifies the use of a CPU from the Apollo Lake family.

1
boards/x86/qemu_x86/Kconfig.board
View file

@ -11,4 +11,5 @@ config BOARD_QEMU_X86_64
bool "QEMU x86_64" bool "QEMU x86_64"
depends on SOC_IA32 depends on SOC_IA32
select QEMU_TARGET select QEMU_TARGET
select X86_NO_MELTDOWN # Until KPTI is enabled, allow testing
select X86_64 select X86_64