linux-kernel - Re: [RFC PATCH v2 14/32] x86: mm: Provide support to use memblock when spliting large pages

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Message-ID: <55f528b7-da06-2506-2cd0-56b9493347f0@redhat.com>
Date:   Thu, 16 Mar 2017 13:28:01 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Brijesh Singh <brijesh.singh@....com>, simon.guinot@...uanux.org,
        linux-efi@...r.kernel.org, kvm@...r.kernel.org, rkrcmar@...hat.com,
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        paul.gortmaker@...driver.com, hpa@...or.com, cl@...ux.com,
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Subject: Re: [RFC PATCH v2 14/32] x86: mm: Provide support to use memblock
 when spliting large pages



On 02/03/2017 16:15, Brijesh Singh wrote:
> 
>  __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
> -		   struct page *base)
> +		  pte_t *pbase, unsigned long new_pfn)
>  {
> -	pte_t *pbase = (pte_t *)page_address(base);

Just one comment and I'll reply to Boris, I think you can compute pbase 
with pfn_to_kaddr, and avoid adding a new argument.

>  	 */
> -	__set_pmd_pte(kpte, address, mk_pte(base, __pgprot(_KERNPG_TABLE)));
> +	__set_pmd_pte(kpte, address,
> +		native_make_pte((new_pfn << PAGE_SHIFT) + _KERNPG_TABLE));

And this probably is better written as:

	__set_pmd_pte(kpte, address, pfn_pte(new_pfn, __pgprot(_KERNPG_TABLE));

Paolo