linux-kernel - Re: [patch 02/10] x86/mm/cpa: Rework static

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Date:   Fri, 7 Sep 2018 09:21:32 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Peter Zijlstra <peterz@...radead.org>,
        Bin Yang <bin.yang@...el.com>,
        Mark Gross <mark.gross@...el.com>
Subject: Re: [patch 02/10] x86/mm/cpa: Rework static_protections()

On 09/07/2018 08:01 AM, Thomas Gleixner wrote:
> +static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
> +					  unsigned long pfn)
> +{
> +	pgprotval_t forbidden;
> +
> +	/* Operate on the virtual address */
> +	forbidden  = protect_kernel_text(address);
> +	forbidden |= protect_kernel_text_ro(address);
> +
> +	/* Check the PFN directly */
> +	forbidden |= protect_pci_bios(pfn);
> +	forbidden |= protect_rodata(pfn);
>  
> -	return prot;
> +	return __pgprot(pgprot_val(prot) & ~forbidden);
>  }

Wow, that's quite an improvement, especially separating the vaddr vs.
paddr checks.