Re: [PATCH v7 04/15] x86/sgx: Implement basic EPC misc cgroup functionality

["Haitao Huang" <haitao.huang@linux.intel.com>]

On Mon, 22 Jan 2024 14:25:53 -0600, Jarkko Sakkinen <jarkko@kernel.org>  
wrote:

> On Mon Jan 22, 2024 at 7:20 PM EET, Haitao Huang wrote:
>> From: Kristen Carlson Accardi <kristen@linux.intel.com>
>>
>> SGX Enclave Page Cache (EPC) memory allocations are separate from normal
>> RAM allocations, and are managed solely by the SGX subsystem. The
>> existing cgroup memory controller cannot be used to limit or account for
>> SGX EPC memory, which is a desirable feature in some environments.  For
>> example, in a Kubernates environment, a user can request certain EPC
>> quota for a pod but the orchestrator can not enforce the quota to limit
>> runtime EPC usage of the pod without an EPC cgroup controller.
>>
>> Utilize the misc controller [admin-guide/cgroup-v2.rst, 5-9. Misc] to
>> limit and track EPC allocations per cgroup. Earlier patches have added
>> the "sgx_epc" resource type in the misc cgroup subsystem. Add basic
>> support in SGX driver as the "sgx_epc" resource provider:
>>
>> - Set "capacity" of EPC by calling misc_cg_set_capacity()
>> - Update EPC usage counter, "current", by calling charge and uncharge
>> APIs for EPC allocation and deallocation, respectively.
>> - Setup sgx_epc resource type specific callbacks, which perform
>> initialization and cleanup during cgroup allocation and deallocation,
>> respectively.
>>
>> With these changes, the misc cgroup controller enables user to set a  
>> hard
>> limit for EPC usage in the "misc.max" interface file. It reports current
>> usage in "misc.current", the total EPC memory available in
>> "misc.capacity", and the number of times EPC usage reached the max limit
>> in "misc.events".
>>
>> For now, the EPC cgroup simply blocks additional EPC allocation in
>> sgx_alloc_epc_page() when the limit is reached. Reclaimable pages are
>> still tracked in the global active list, only reclaimed by the global
>> reclaimer when the total free page count is lower than a threshold.
>>
>> Later patches will reorganize the tracking and reclamation code in the
>> global reclaimer and implement per-cgroup tracking and reclaiming.
>>
>> 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>
>
> For consistency sake I'd also add co-developed-by for Kristen. This is
> at least the format suggested by kernel documentation.
>
She is the "From Author", so only Signed-off-by is needed for her  
according to the second example in the doc[1]?

Thanks
Haitao
[1]https://docs.kernel.org/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by