linux-kernel - Re: [PATCH v1 1/3] x86/mm: Centralize PMD flags in sme_encrypt

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Message-ID: <20171220191301.6ak5kzs5mi6h3vvg@pd.tnic>
Date:   Wed, 20 Dec 2017 20:13:01 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Tom Lendacky <thomas.lendacky@....com>
Cc:     x86@...nel.org, Brijesh Singh <brijesh.singh@....com>,
        linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v1 1/3] x86/mm: Centralize PMD flags in
 sme_encrypt_kernel()

On Thu, Dec 07, 2017 at 05:33:52PM -0600, Tom Lendacky wrote:
> In preparation for encrypting more than just the kernel during early
> boot processing, centralize the use of the PMD flag settings based
> on the type of mapping desired.  When 4KB aligned encryption is added,
> this will allow either PTE flags or large page PMD flags to be used
> without requiring the caller to adjust.
> 
> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
> ---
>  arch/x86/mm/mem_encrypt.c |  109 +++++++++++++++++++++++++--------------------
>  1 file changed, 60 insertions(+), 49 deletions(-)
> 
> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
> index d9a9e9f..2d8404b 100644
> --- a/arch/x86/mm/mem_encrypt.c
> +++ b/arch/x86/mm/mem_encrypt.c
> @@ -464,6 +464,8 @@ void swiotlb_set_mem_attributes(void *vaddr, unsigned long size)
>  	set_memory_decrypted((unsigned long)vaddr, size >> PAGE_SHIFT);
>  }
>  
> +static void *pgtable_area;

Ewww, a global variable which gets manipulated by functions. Can we not
do that pls?

sme_populate_pgd() used to return it. Why change that?

> +
>  static void __init sme_clear_pgd(pgd_t *pgd_base, unsigned long start,
>  				 unsigned long end)
>  {
> @@ -484,10 +486,16 @@ static void __init sme_clear_pgd(pgd_t *pgd_base, unsigned long start,
>  #define PGD_FLAGS	_KERNPG_TABLE_NOENC
>  #define P4D_FLAGS	_KERNPG_TABLE_NOENC
>  #define PUD_FLAGS	_KERNPG_TABLE_NOENC
> -#define PMD_FLAGS	(__PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL)
>  
> -static void __init *sme_populate_pgd(pgd_t *pgd_base, void *pgtable_area,
> -				     unsigned long vaddr, pmdval_t pmd_val)
> +#define PMD_FLAGS_LARGE		(__PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL)
> +
> +#define PMD_FLAGS_DEC		PMD_FLAGS_LARGE
> +#define PMD_FLAGS_DEC_WP	((PMD_FLAGS_DEC & ~_PAGE_CACHE_MASK) | \
> +				 (_PAGE_PAT | _PAGE_PWT))
> +#define PMD_FLAGS_ENC		(PMD_FLAGS_LARGE | _PAGE_ENC)

Align vertically.

Rest looks ok.

-- 
Regards/Gruss,
    Boris.

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