linux-kernel - Re: [PATCH v3 03/28] x86/sgx: Add 'struct sgx_epc_lru

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Message-Id: <CU4GHCJTRKLZ.1RK23NWPHJGNI@seitikki>
Date:   Mon, 17 Jul 2023 12:45:36 +0000
From:   "Jarkko Sakkinen" <jarkko@...nel.org>
To:     "Haitao Huang" <haitao.huang@...ux.intel.com>,
        <dave.hansen@...ux.intel.com>, <tj@...nel.org>,
        <linux-kernel@...r.kernel.org>, <linux-sgx@...r.kernel.org>,
        <cgroups@...r.kernel.org>, "Thomas Gleixner" <tglx@...utronix.de>,
        "Ingo Molnar" <mingo@...hat.com>, "Borislav Petkov" <bp@...en8.de>,
        <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>
Cc:     <kai.huang@...el.com>, <reinette.chatre@...el.com>,
        "Kristen Carlson Accardi" <kristen@...ux.intel.com>,
        <zhiquan1.li@...el.com>, <seanjc@...gle.com>
Subject: Re: [PATCH v3 03/28] x86/sgx: Add 'struct sgx_epc_lru_lists' to
 encapsulate lru list(s)

On Wed Jul 12, 2023 at 11:01 PM UTC, Haitao Huang wrote:
> From: Kristen Carlson Accardi <kristen@...ux.intel.com>
>
> Introduce a data structure to wrap the existing reclaimable list
> and its spinlock in a struct to minimize the code changes needed
> to handle multiple LRUs as well as reclaimable and non-reclaimable
> lists. The new structure will be used in a following set of patches to
> implement SGX EPC cgroups.
>
> The changes to the structure needed for unreclaimable lists will be
> added in later patches.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Kristen Carlson Accardi <kristen@...ux.intel.com>
> Signed-off-by: Haitao Huang <haitao.huang@...ux.intel.com>
> Cc: Sean Christopherson <seanjc@...gle.com>
>
> V3:
> Removed the helper functions and revised commit messages
> ---
>  arch/x86/kernel/cpu/sgx/sgx.h | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
> index f6e3c5810eef..77fceba73a25 100644
> --- a/arch/x86/kernel/cpu/sgx/sgx.h
> +++ b/arch/x86/kernel/cpu/sgx/sgx.h
> @@ -92,6 +92,23 @@ static inline void *sgx_get_epc_virt_addr(struct sgx_epc_page *page)
>  	return section->virt_addr + index * PAGE_SIZE;
>  }
>  
> +/*
> + * This data structure wraps a list of reclaimable EPC pages, and a list of
> + * non-reclaimable EPC pages and is used to implement a LRU policy during
> + * reclamation.
> + */
> +struct sgx_epc_lru_lists {
> +	/* Must acquire this lock to access */
> +	spinlock_t lock;

Isn't this self-explanatory, why the inline comment?

> +	struct list_head reclaimable;
> +};
> +
> +static inline void sgx_lru_init(struct sgx_epc_lru_lists *lrus)
> +{
> +	spin_lock_init(&lrus->lock);
> +	INIT_LIST_HEAD(&lrus->reclaimable);
> +}
> +
>  struct sgx_epc_page *__sgx_alloc_epc_page(void);
>  void sgx_free_epc_page(struct sgx_epc_page *page);
>  
> -- 
> 2.25.1


BR, Jarkko