Re: [PATCH v9 11/15] x86/sgx: Abstract check for global reclaimable pages

Jarkko Sakkinen
2024-02-12T19:56:46Z

On Mon Feb 5, 2024 at 11:06 PM EET, Haitao Huang wrote:
> From: Kristen Carlson Accardi <kristen@linux.intel.com>
>
> To determine if any page available for reclamation at the global level,
> only checking for emptiness of the global LRU is not adequate when pages
> are tracked in multiple LRUs, one per cgroup. For this purpose, create a
> new helper, sgx_can_reclaim(), currently only checks the global LRU,
> later will check emptiness of LRUs of all cgroups when per-cgroup
> tracking is turned on. Replace all the checks of the global LRU,
> list_empty(&sgx_global_lru.reclaimable), with calls to
> sgx_can_reclaim().
>
> Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
> Co-developed-by: Haitao Huang <haitao.huang@linux.intel.com>
> Signed-off-by: Haitao Huang <haitao.huang@linux.intel.com>
> ---
> v7:
> - Split this out from the big patch, #10 in V6. (Dave, Kai)
> ---
> arch/x86/kernel/cpu/sgx/main.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> index 2279ae967707..6b0c26cac621 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -37,6 +37,11 @@ static inline struct sgx_epc_lru_list *sgx_lru_list(struct sgx_epc_page *epc_pag
> return &sgx_global_lru;
> }
>

/*
* Description
*/
> +static inline bool sgx_can_reclaim(void)
> +{
> + return !list_empty(&sgx_global_lru.reclaimable);
> +}
> +
> static atomic_long_t sgx_nr_free_pages = ATOMIC_LONG_INIT(0);
>
> /* Nodes with one or more EPC sections. */
> @@ -398,7 +403,7 @@ unsigned int sgx_reclaim_pages(struct sgx_epc_lru_list *lru, unsigned int *nr_to
> static bool sgx_should_reclaim(unsigned long watermark)
> {
> return atomic_long_read(&sgx_nr_free_pages) < watermark &&
> - !list_empty(&sgx_global_lru.reclaimable);
> + sgx_can_reclaim();
> }
>
> static void sgx_reclaim_pages_global(bool indirect)
> @@ -601,7 +606,7 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim)
> break;
> }
>
> - if (list_empty(&sgx_global_lru.reclaimable)) {
> + if (!sgx_can_reclaim()) {
> page = ERR_PTR(-ENOMEM);
> break;
> }

BR, Jarkko