Messages in this thread | | | Subject | Re: [PATCH v5 02/18] cgroup/misc: Add SGX EPC resource type and export APIs for SGX driver | Date | Tue, 03 Oct 2023 02:00:04 -0500 | From | "Haitao Huang" <> |
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On Wed, 27 Sep 2023 22:59:12 -0500, Huang, Kai <kai.huang@intel.com> wrote:
> On Fri, 2023-09-22 at 20:06 -0700, Haitao Huang wrote: >> From: Kristen Carlson Accardi <kristen@linux.intel.com> >> >> Add SGX EPC memory, MISC_CG_RES_SGX_EPC, to be a valid resource type >> for the misc controller. >> >> Add per resource type private data so that SGX can store additional per >> cgroup data in misc_cg->misc_cg_res[MISC_CG_RES_SGX_EPC]. > > To be honest I don't quite understand why putting the above two changes > in this > patch together with exporting misc_cg_root/parent() below. > > Any reason why the above two cannot be done together with patch (" > x86/sgx: > Limit process EPC usage with misc cgroup controller"), where these > changes are > actually related? > > We all already know that a new EPC misc cgroup will be added. There's > no need > to actually introduce the new type here only to justify exporting some > helper > functions. >
I think previous authors intended to separate all prerequisite misc changes from SGX changes. I can combine them if maintainers are fine with it.
>> >> Export misc_cg_root() so the SGX driver can initialize and add those >> additional structures to the root misc cgroup as part of initialization >> for EPC cgroup support. This bootstraps the same additional >> initialization for non-root cgroups in the 'alloc()' callback added in >> the >> previous patch. >> >> The SGX driver, as the EPC memory provider, will have a background >> worker to reclaim EPC pages to make room for new allocations in the same >> cgroup when its usage counter reaches near the limit controlled by the >> cgroup and its ancestors. Therefore it needs to do a walk from the >> current cgroup up to the root. To enable this walk, move parent_misc() >> into misc_cgroup.h and make inline to make this function available to >> SGX, rename it to misc_cg_parent(), and update kernel/cgroup/misc.c to >> use the new name. > > Looks too many details in the above two paragraphs. Could we have a more > concise justification for exporting these two functions? >
This was added to address Jarkko's question, "why does SGX driver need to do iterative walks?" See: https://lore.kernel.org/all/CVHOU5G1SCUT.RCBVZ3W8G2NJ@suppilovahvero/
> And if it were me, I would put it at a relatively later position (e.g., > before > the patch actually implements EPC cgroup) for better review. This also > applies > to the first patch. >
I was told to move all prerequisites to the front or separate out.
https://lore.kernel.org/linux-sgx/CU4H43P3H35X.1BCA3CE4D1250@seitikki/
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