linux-kernel - Re: [PATCH Part2 v6 08/49] x86/traps: Define RMP violation #PF error code

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Date:   Mon, 8 Aug 2022 15:13:08 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Ashish Kalra <Ashish.Kalra@....com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        linux-crypto@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
        jroedel@...e.de, thomas.lendacky@....com, hpa@...or.com,
        ardb@...nel.org, pbonzini@...hat.com, seanjc@...gle.com,
        vkuznets@...hat.com, jmattson@...gle.com, luto@...nel.org,
        dave.hansen@...ux.intel.com, slp@...hat.com, pgonda@...gle.com,
        peterz@...radead.org, srinivas.pandruvada@...ux.intel.com,
        rientjes@...gle.com, dovmurik@...ux.ibm.com, tobin@....com,
        michael.roth@....com, vbabka@...e.cz, kirill@...temov.name,
        ak@...ux.intel.com, tony.luck@...el.com, marcorr@...gle.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com, alpergun@...gle.com,
        dgilbert@...hat.com, jarkko@...nel.org
Subject: Re: [PATCH Part2 v6 08/49] x86/traps: Define RMP violation #PF error
 code

On Mon, Jun 20, 2022 at 11:03:27PM +0000, Ashish Kalra wrote:
> @@ -12,15 +14,17 @@
>   *   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 due to RMP violation
>   */
>  enum x86_pf_error_code {
> -	X86_PF_PROT	=		1 << 0,
> -	X86_PF_WRITE	=		1 << 1,
> -	X86_PF_USER	=		1 << 2,
> -	X86_PF_RSVD	=		1 << 3,
> -	X86_PF_INSTR	=		1 << 4,
> -	X86_PF_PK	=		1 << 5,
> -	X86_PF_SGX	=		1 << 15,
> +	X86_PF_PROT	=		BIT_ULL(0),
> +	X86_PF_WRITE	=		BIT_ULL(1),
> +	X86_PF_USER	=		BIT_ULL(2),
> +	X86_PF_RSVD	=		BIT_ULL(3),
> +	X86_PF_INSTR	=		BIT_ULL(4),
> +	X86_PF_PK	=		BIT_ULL(5),
> +	X86_PF_SGX	=		BIT_ULL(15),
> +	X86_PF_RMP	=		BIT_ULL(31),

Yeah, I remember dhansen asked for those to use the BIT() macro but the
_ULL is an overkill. Those PF flags are 32 and they fit in an unsigned
int.

But we don't have BUT_UI() so I guess the next best thing - BIT() -
which uses UL internally, should be good enough.

So pls use BIT() here - not BIT_ULL().

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette