Re: [PATCH v4 03/18] x86/sgx: Add sgx_epc_lru_lists to encapsulate LRU lists

Jarkko Sakkinen
2023-09-13T09:46:16Z

On Wed Sep 13, 2023 at 7:06 AM EEST, Haitao Huang wrote:
> From: Kristen Carlson Accardi <kristen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
>
> Introduce a data structure to wrap the existing reclaimable list and its
> spinlock. Each cgroup later will have one instance of this structure to
> track EPC pages allocated for processes associated with the same cgroup.
> Just like the global SGX reclaimer (ksgxd), an EPC cgroup reclaims pages
> from the reclaimable list in this structure when its usage reaches near
> its limit.
>
> Currently, ksgxd does not track the VA, SECS pages. They are considered
> as 'unreclaimable' pages that are only deallocated when their respective
> owning enclaves are destroyed and all associated resources released.
>
> When an EPC cgroup can not reclaim any more reclaimable EPC pages to
> reduce its usage below its limit, the cgroup must also reclaim those
> unreclaimables by killing their owning enclaves. The VA and SECS pages
> later are also tracked in an 'unreclaimable' list added to this structure
> to support this OOM killing of enclaves.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> Signed-off-by: Kristen Carlson Accardi <kristen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> Signed-off-by: Haitao Huang <haitao.huang-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> Cc: Sean Christopherson <seanjc-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> ---
> V4:
> - Removed unneeded comments for the spinlock and the non-reclaimables.
> (Kai, Jarkko)
> - Revised the commit to add introduction comments for unreclaimables and
> multiple LRU lists.(Kai)
> - Reordered the patches: delay all changes for unreclaimables to
> later, and this one becomes the first change in the SGX subsystem.
>
> V3:
> - Removed the helper functions and revised commit messages.
> ---
> arch/x86/kernel/cpu/sgx/sgx.h | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
> index d2dad21259a8..018414b2abe8 100644
> --- a/arch/x86/kernel/cpu/sgx/sgx.h
> +++ b/arch/x86/kernel/cpu/sgx/sgx.h
> @@ -83,6 +83,20 @@ static inline void *sgx_get_epc_virt_addr(struct sgx_epc_page *page)
> return section->virt_addr + index * PAGE_SIZE;
> }
>
> +/*
> + * Tracks EPC pages reclaimable by the reclaimer (ksgxd).
> + */
> +struct sgx_epc_lru_lists {
> + spinlock_t lock;
> + 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
>

Looks good but not yet time for ack'ing.

BR, Jarkko