Re: [PATCH v33 09/21] x86/sgx: Add __sgx_alloc_epc_page() and sgx_free_epc_page()

[Borislav Petkov]

On Thu, Jun 18, 2020 at 01:08:31AM +0300, Jarkko Sakkinen wrote:
> Add __sgx_alloc_epc_page(), which iterates through EPC sections and borrows
> a page structure that is not used by anyone else. When a page is no longer
> needed it must be released with sgx_free_epc_page(). This function
> implicitly calls ENCLS[EREMOVE], which will return the page to the
> uninitialized state (i.e. not required from caller part).
> 
> Acked-by: Jethro Beekman <jethro@xxxxxxxxxxxx>
> Co-developed-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
> ---
>  arch/x86/kernel/cpu/sgx/main.c | 61 ++++++++++++++++++++++++++++++++++
>  arch/x86/kernel/cpu/sgx/sgx.h  |  3 ++
>  2 files changed, 64 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> index c5831e3db14a..b776d249289f 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -83,6 +83,67 @@ static bool __init sgx_page_reclaimer_init(void)
>  	return true;
>  }
>  
> +static struct sgx_epc_page *__sgx_alloc_epc_page_from_section(struct sgx_epc_section *section)
> +{
> +	struct sgx_epc_page *page;
> +
> +	if (list_empty(&section->page_list))
> +		return NULL;
> +
> +	page = list_first_entry(&section->page_list, struct sgx_epc_page, list);
> +	list_del_init(&page->list);

<---- newline here.

> +	return page;
> +}

Otherwise looks good; nice comments.

Thx.

-- 
Regards/Gruss,
    Boris.

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