On 05/05/2017 20:17, Ricardo Neri wrote:
> User-Mode Instruction Prevention is a security feature present in new
> Intel processors that, when set, prevents the execution of a subset of
> instructions if such instructions are executed in user mode (CPL > 0).
> Attempting to execute such instructions causes a general protection
> exception.
> 
> The subset of instructions comprises:
> 
>  * SGDT - Store Global Descriptor Table
>  * SIDT - Store Interrupt Descriptor Table
>  * SLDT - Store Local Descriptor Table
>  * SMSW - Store Machine Status Word
>  * STR  - Store Task Register
> 
> This feature is also added to the list of disabled-features to allow
> a cleaner handling of build-time configuration.
> 
> Cc: Andy Lutomirski <l...@kernel.org>
> Cc: Andrew Morton <a...@linux-foundation.org>
> Cc: H. Peter Anvin <h...@zytor.com>
> Cc: Borislav Petkov <b...@suse.de>
> Cc: Brian Gerst <brge...@gmail.com>
> Cc: Chen Yucong <sla...@gmail.com>
> Cc: Chris Metcalf <cmetc...@mellanox.com>
> Cc: Dave Hansen <dave.han...@linux.intel.com>
> Cc: Fenghua Yu <fenghua...@intel.com>
> Cc: Huang Rui <ray.hu...@amd.com>
> Cc: Jiri Slaby <jsl...@suse.cz>
> Cc: Jonathan Corbet <cor...@lwn.net>
> Cc: Michael S. Tsirkin <m...@redhat.com>
> Cc: Paul Gortmaker <paul.gortma...@windriver.com>
> Cc: Peter Zijlstra <pet...@infradead.org>
> Cc: Ravi V. Shankar <ravi.v.shan...@intel.com>
> Cc: Shuah Khan <sh...@kernel.org>
> Cc: Vlastimil Babka <vba...@suse.cz>
> Cc: Tony Luck <tony.l...@intel.com>
> Cc: Paolo Bonzini <pbonz...@redhat.com>
> Cc: Liang Z. Li <liang.z...@intel.com>
> Cc: Alexandre Julliard <julli...@winehq.org>
> Cc: Stas Sergeev <s...@list.ru>
> Cc: x...@kernel.org
> Cc: linux-msdos@vger.kernel.org
> 
> Signed-off-by: Ricardo Neri <ricardo.neri-calde...@linux.intel.com>

Would it be possible to have this patch in a topic branch for KVM's
consumption?

Thanks,

Paolo

> ---
>  arch/x86/include/asm/cpufeatures.h          | 1 +
>  arch/x86/include/asm/disabled-features.h    | 8 +++++++-
>  arch/x86/include/uapi/asm/processor-flags.h | 2 ++
>  3 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/cpufeatures.h 
> b/arch/x86/include/asm/cpufeatures.h
> index 2701e5f..f1d61d2 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -289,6 +289,7 @@
>  
>  /* Intel-defined CPU features, CPUID level 0x00000007:0 (ecx), word 16 */
>  #define X86_FEATURE_AVX512VBMI  (16*32+ 1) /* AVX512 Vector Bit Manipulation 
> instructions*/
> +#define X86_FEATURE_UMIP     (16*32+ 2) /* User Mode Instruction Protection 
> */
>  #define X86_FEATURE_PKU              (16*32+ 3) /* Protection Keys for 
> Userspace */
>  #define X86_FEATURE_OSPKE    (16*32+ 4) /* OS Protection Keys Enable */
>  #define X86_FEATURE_AVX512_VPOPCNTDQ (16*32+14) /* POPCNT for vectors of 
> DW/QW */
> diff --git a/arch/x86/include/asm/disabled-features.h 
> b/arch/x86/include/asm/disabled-features.h
> index 5dff775..7adaef7 100644
> --- a/arch/x86/include/asm/disabled-features.h
> +++ b/arch/x86/include/asm/disabled-features.h
> @@ -16,6 +16,12 @@
>  # define DISABLE_MPX (1<<(X86_FEATURE_MPX & 31))
>  #endif
>  
> +#ifdef CONFIG_X86_INTEL_UMIP
> +# define DISABLE_UMIP        0
> +#else
> +# define DISABLE_UMIP        (1<<(X86_FEATURE_UMIP & 31))
> +#endif
> +
>  #ifdef CONFIG_X86_64
>  # define DISABLE_VME         (1<<(X86_FEATURE_VME & 31))
>  # define DISABLE_K6_MTRR     (1<<(X86_FEATURE_K6_MTRR & 31))
> @@ -61,7 +67,7 @@
>  #define DISABLED_MASK13      0
>  #define DISABLED_MASK14      0
>  #define DISABLED_MASK15      0
> -#define DISABLED_MASK16      (DISABLE_PKU|DISABLE_OSPKE|DISABLE_LA57)
> +#define DISABLED_MASK16      
> (DISABLE_PKU|DISABLE_OSPKE|DISABLE_LA57|DISABLE_UMIP)
>  #define DISABLED_MASK17      0
>  #define DISABLED_MASK_CHECK BUILD_BUG_ON_ZERO(NCAPINTS != 18)
>  
> diff --git a/arch/x86/include/uapi/asm/processor-flags.h 
> b/arch/x86/include/uapi/asm/processor-flags.h
> index 567de50..d2c2af8 100644
> --- a/arch/x86/include/uapi/asm/processor-flags.h
> +++ b/arch/x86/include/uapi/asm/processor-flags.h
> @@ -104,6 +104,8 @@
>  #define X86_CR4_OSFXSR               _BITUL(X86_CR4_OSFXSR_BIT)
>  #define X86_CR4_OSXMMEXCPT_BIT       10 /* enable unmasked SSE exceptions */
>  #define X86_CR4_OSXMMEXCPT   _BITUL(X86_CR4_OSXMMEXCPT_BIT)
> +#define X86_CR4_UMIP_BIT     11 /* enable UMIP support */
> +#define X86_CR4_UMIP         _BITUL(X86_CR4_UMIP_BIT)
>  #define X86_CR4_VMXE_BIT     13 /* enable VMX virtualization */
>  #define X86_CR4_VMXE         _BITUL(X86_CR4_VMXE_BIT)
>  #define X86_CR4_SMXE_BIT     14 /* enable safer mode (TXT) */
> 
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