Re: [RFC Part2 PATCH 05/30] x86: define RMP violation #PF error code

[Dave Hansen]

> diff --git a/arch/x86/include/asm/trap_pf.h b/arch/x86/include/asm/trap_pf.h
> index 10b1de500ab1..107f9d947e8d 100644
> --- a/arch/x86/include/asm/trap_pf.h
> +++ b/arch/x86/include/asm/trap_pf.h
> @@ -12,6 +12,7 @@
>   *   bit 4 ==				1: fault was an instruction fetch
>   *   bit 5 ==				1: protection keys block access
>   *   bit 15 ==				1: SGX MMU page-fault
> + *   bit 31 ==				1: fault was an RMP violation
>   */
>  enum x86_pf_error_code {
>  	X86_PF_PROT	=		1 << 0,
> @@ -21,6 +22,7 @@ enum x86_pf_error_code {
>  	X86_PF_INSTR	=		1 << 4,
>  	X86_PF_PK	=		1 << 5,
>  	X86_PF_SGX	=		1 << 15,
> +	X86_PF_RMP	=		1ull << 31,
>  };

Man, I hope AMD and Intel are talking to each other about these bits.  :)

Either way, this is hitting the limits of what I know about how enums
are implemented.  I had internalized that they are just an 'int', but
that doesn't seem quite right.  It sounds like they must be implemented
using *an* integer type, but not necessarily 'int' itself.

Either way, '1<<31' doesn't fit in a 32-bit signed int.  But, gcc at
least doesn't seem to blow the enum up into a 64-bit type, which is nice.

Could we at least start declaring these with BIT()?