linux-kernel - Re: [PATCH v4 4/4] x86/mm/KASLR: Adjust the padding size for the direct mapping.

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Message-ID: <20191114081638.GH30906@MiWiFi-R3L-srv>
Date:   Thu, 14 Nov 2019 16:16:38 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Masayoshi Mizuma <msys.mizuma@...il.com>
Cc:     Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Masayoshi Mizuma <m.mizuma@...fujitsu.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 4/4] x86/mm/KASLR: Adjust the padding size for the
 direct  mapping.

On 11/12/19 at 03:47pm, Masayoshi Mizuma wrote:
> Your suggesion makes it simpler, thanks!
> So I'll modify calc_direct_mapping_size() as following.
> Does it make sense?

Yeah, it looks good to me. Thanks.

> 
> static inline unsigned long calc_direct_mapping_size(void)
> {
>        unsigned long size_tb, memory_tb;
> 
>        memory_tb = DIV_ROUND_UP(max_pfn << PAGE_SHIFT, 1UL << TB_SHIFT) +
>                CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING;
> 
> #ifdef CONFIG_MEMORY_HOTPLUG
>        if (boot_params.max_addr) {
>                unsigned long maximum_tb;
> 
>                maximum_tb = DIV_ROUND_UP(boot_params.max_addr,
>                                1UL << TB_SHIFT);
> 
>                if (maximum_tb > memory_tb)
>                        memory_tb = maximum_tb;
>        }
> #endif
>        size_tb = 1 << (MAX_PHYSMEM_BITS - TB_SHIFT);
> 
>        /*
>         * Adapt physical memory region size based on available memory
>         */
>        if (memory_tb < size_tb)
>                size_tb = memory_tb;
> 
>        return size_tb;
> }