linux-kernel - Re: [PATCH v24 06/24] x86/sgx: Add wrappers for ENCLS leaf functions

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Date:   Tue, 17 Dec 2019 15:45:48 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        linux-sgx@...r.kernel.org, akpm@...ux-foundation.org,
        dave.hansen@...el.com, sean.j.christopherson@...el.com,
        nhorman@...hat.com, npmccallum@...hat.com, serge.ayoun@...el.com,
        shay.katz-zamir@...el.com, haitao.huang@...el.com,
        andriy.shevchenko@...ux.intel.com, tglx@...utronix.de,
        kai.svahn@...el.com, josh@...htriplett.org, luto@...nel.org,
        kai.huang@...el.com, rientjes@...gle.com, cedric.xing@...el.com,
        puiterwijk@...hat.com
Subject: Re: [PATCH v24 06/24] x86/sgx: Add wrappers for ENCLS leaf functions

On Sat, Nov 30, 2019 at 01:13:08AM +0200, Jarkko Sakkinen wrote:
> +/**
> + * encls_failed() - Check if an ENCLS leaf function failed
> + * @ret:	the return value of an ENCLS leaf function call
> + *
> + * Check if an ENCLS leaf function failed. This happens when the leaf function
> + * causes a fault that is not caused by an EPCM conflict or when the leaf
> + * function returns a non-zero value.
> + */
> +static inline bool encls_failed(int ret)
> +{
> +	int epcm_trapnr =
> +		boot_cpu_has(X86_FEATURE_SGX2) ? X86_TRAP_PF : X86_TRAP_GP;
> +	bool fault = ret & ENCLS_FAULT_FLAG;
> +
> +	return (fault && ENCLS_TRAPNR(ret) != epcm_trapnr) || (!fault && ret);
> +}

Can we make this function more readable?

static inline bool encls_failed(int ret)
{
        int epcm_trapnr;

        if (boot_cpu_has(X86_FEATURE_SGX2))
                epcm_trapnr = X86_TRAP_PF;
        else
                epcm_trapnr = X86_TRAP_GP;

        if (ret & ENCLS_FAULT_FLAG)
                return ENCLS_TRAPNR(ret) != epcm_trapnr;

        return !!ret;
}

I hope I've converted it correctly but I might've missed some corner
case...

Thx.

-- 
Regards/Gruss,
    Boris.

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