Messages in this thread Patch in this message | | | From | Ricardo Neri <> | Subject | [RESEND PATCH v2 1/4] x86/umip: Select X86_INTEL_UMIP by default | Date | Mon, 13 Nov 2017 22:29:42 -0800 |
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UMIP does not incur in a significant performance penalty. Furthermore, it is triggered only when a small group of instructions are used from user space programs.
While here, provide more details on the benefits UMIP provides and the behavior that can expect the few applications that use the instructions protected by UMIP.
Cc: Andy Lutomirski <luto@kernel.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Borislav Petkov <bp@suse.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Ravi V. Shankar <ravi.v.shankar@intel.com> Cc: x86@kernel.org Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> --- arch/x86/Kconfig | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index f08977d..a524a7a 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1805,14 +1805,20 @@ config X86_SMAP If unsure, say Y. config X86_INTEL_UMIP - def_bool n + def_bool y depends on CPU_SUP_INTEL prompt "Intel User Mode Instruction Prevention" if EXPERT ---help--- The User Mode Instruction Prevention (UMIP) is a security feature in newer Intel processors. If enabled, a general protection fault is issued if the instructions SGDT, SLDT, - SIDT, SMSW and STR are executed in user mode. + SIDT, SMSW and STR are executed in user mode. These instructions + unnecessarily expose information about the hardware state. + + The vast majority of applications do not use these instructions. + For the very few that do, software emulation is provided in + specific cases in protected and virtual-8086 modes. Emulated + results are dummy. config X86_INTEL_MPX prompt "Intel MPX (Memory Protection Extensions)" -- 2.7.4
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