linux-kernel - Re: [PATCH 03/26] x86/sgx: Add 'struct sgx_epc

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Message-ID: <Y3QiRlwmg2YZmqLQ@kernel.org>
Date:   Wed, 16 Nov 2022 01:35:34 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Kristen Carlson Accardi <kristen@...ux.intel.com>
Cc:     dave.hansen@...ux.kernel.org, tj@...nel.org,
        linux-kernel@...r.kernel.org, linux-sgx@...r.kernel.org,
        cgroups@...r.kernel.org, Dave Hansen <dave.hansen@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        zhiquan1.li@...el.com, Sean Christopherson <seanjc@...gle.com>
Subject: Re: [PATCH 03/26] x86/sgx: Add 'struct sgx_epc_lru' to encapsulate
 lru list(s)

On Fri, Nov 11, 2022 at 10:35:08AM -0800, Kristen Carlson Accardi wrote:
> 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, both of which will be introduced and used by SGX EPC cgroups.
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Kristen Carlson Accardi <kristen@...ux.intel.com>
> Cc: Sean Christopherson <seanjc@...gle.com>
> ---
>  arch/x86/kernel/cpu/sgx/sgx.h | 45 +++++++++++++++++++++++++++++++++++
>  1 file changed, 45 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
> index efb10eacd3aa..aac7d4feb0fa 100644
> --- a/arch/x86/kernel/cpu/sgx/sgx.h
> +++ b/arch/x86/kernel/cpu/sgx/sgx.h
> @@ -91,6 +91,51 @@ static inline void *sgx_get_epc_virt_addr(struct sgx_epc_page *page)
>  	return section->virt_addr + index * PAGE_SIZE;
>  }
>  
> +struct sgx_epc_lru {

It's not an LRU. It's a data structure containing two LRU's.

Please rename and add a descriptive comment.

> +	spinlock_t lock;
> +	struct list_head reclaimable;
> +	struct list_head unreclaimable;
> +};
> +
> +static inline void sgx_lru_init(struct sgx_epc_lru *lru)
> +{
> +	spin_lock_init(&lru->lock);
> +	INIT_LIST_HEAD(&lru->reclaimable);
> +	INIT_LIST_HEAD(&lru->unreclaimable);
> +}
> +
> +/*
> + * Must be called with queue lock acquired
> + */
> +static inline void __sgx_epc_page_list_push(struct list_head *list, struct sgx_epc_page *page)
> +{
> +	list_add_tail(&page->list, list);
> +}
> +
> +/*
> + * Must be called with queue lock acquired
> + */
> +static inline struct sgx_epc_page * __sgx_epc_page_list_pop(struct list_head *list)
> +{
> +	struct sgx_epc_page *epc_page;
> +
> +	if (list_empty(list))
> +		return NULL;
> +
> +	epc_page = list_first_entry(list, struct sgx_epc_page, list);
> +	list_del_init(&epc_page->list);
> +	return epc_page;
> +}
> +
> +#define sgx_epc_pop_reclaimable(lru) \
> +	__sgx_epc_page_list_pop(&(lru)->reclaimable)
> +#define sgx_epc_push_reclaimable(lru, page) \
> +	__sgx_epc_page_list_push(&(lru)->reclaimable, page)
> +#define sgx_epc_pop_unreclaimable(lru) \
> +	__sgx_epc_page_list_pop(&(lru)->unreclaimable)
> +#define sgx_epc_push_unreclaimable(lru, page) \
> +	__sgx_epc_page_list_push(&(lru)->unreclaimable, page)

Is there any reason not to declare these as inline functions?

> +
>  struct sgx_epc_page *__sgx_alloc_epc_page(void);
>  void sgx_free_epc_page(struct sgx_epc_page *page);
>  
> -- 
> 2.37.3
> 

BR, Jarkko