From: Haitao Huang <haitao.huang@linux.intel.com>
To: jarkko@kernel.org, dave.hansen@linux.intel.com, tj@kernel.org,
linux-kernel@vger.kernel.org, linux-sgx@vger.kernel.org,
x86@kernel.org, cgroups@vger.kernel.org, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, hpa@zytor.com,
sohil.mehta@intel.com
Cc: zhiquan1.li@intel.com, kristen@linux.intel.com,
seanjc@google.com, zhanb@microsoft.com, anakrish@microsoft.com,
mikko.ylinen@linux.intel.com, yangjie@microsoft.com
Subject: [PATCH v5 17/18] Docs/x86/sgx: Add description for cgroup support
Date: Fri, 22 Sep 2023 20:06:56 -0700 [thread overview]
Message-ID: <20230923030657.16148-18-haitao.huang@linux.intel.com> (raw)
In-Reply-To: <20230923030657.16148-1-haitao.huang@linux.intel.com>
From: Sean Christopherson <sean.j.christopherson@intel.com>
Add initial documentation of how to regulate the distribution of
SGX Enclave Page Cache (EPC) memory via the Miscellaneous cgroup
controller.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Co-developed-by: Kristen Carlson Accardi <kristen@linux.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>
Cc: Sean Christopherson <seanjc@google.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
---
V4:
- Fix indentation (Randy)
- Change misc.events file to be read-only
- Fix a typo for 'subsystem'
- Add behavior when VMM overcommit EPC with a cgroup (Mikko)
---
Documentation/arch/x86/sgx.rst | 82 ++++++++++++++++++++++++++++++++++
1 file changed, 82 insertions(+)
diff --git a/Documentation/arch/x86/sgx.rst b/Documentation/arch/x86/sgx.rst
index d90796adc2ec..65c211bd5342 100644
--- a/Documentation/arch/x86/sgx.rst
+++ b/Documentation/arch/x86/sgx.rst
@@ -300,3 +300,85 @@ to expected failures and handle them as follows:
first call. It indicates a bug in the kernel or the userspace client
if any of the second round of ``SGX_IOC_VEPC_REMOVE_ALL`` calls has
a return code other than 0.
+
+
+Cgroup Support
+==============
+
+The "sgx_epc" resource within the Miscellaneous cgroup controller regulates
+distribution of SGX EPC memory, which is a subset of system RAM that
+is used to provide SGX-enabled applications with protected memory,
+and is otherwise inaccessible, i.e. shows up as reserved in
+/proc/iomem and cannot be read/written outside of an SGX enclave.
+
+Although current systems implement EPC by stealing memory from RAM,
+for all intents and purposes the EPC is independent from normal system
+memory, e.g. must be reserved at boot from RAM and cannot be converted
+between EPC and normal memory while the system is running. The EPC is
+managed by the SGX subsystem and is not accounted by the memory
+controller. Note that this is true only for EPC memory itself, i.e.
+normal memory allocations related to SGX and EPC memory, e.g. the
+backing memory for evicted EPC pages, are accounted, limited and
+protected by the memory controller.
+
+Much like normal system memory, EPC memory can be overcommitted via
+virtual memory techniques and pages can be swapped out of the EPC
+to their backing store (normal system memory allocated via shmem).
+The SGX EPC subsystem is analogous to the memory subsystem, and
+it implements limit and protection models for EPC memory.
+
+SGX EPC Interface Files
+-----------------------
+
+For a generic description of the Miscellaneous controller interface
+files, please see Documentation/admin-guide/cgroup-v2.rst
+
+All SGX EPC memory amounts are in bytes unless explicitly stated
+otherwise. If a value which is not PAGE_SIZE aligned is written,
+the actual value used by the controller will be rounded down to
+the closest PAGE_SIZE multiple.
+
+ misc.capacity
+ A read-only flat-keyed file shown only in the root cgroup.
+ The sgx_epc resource will show the total amount of EPC
+ memory available on the platform.
+
+ misc.current
+ A read-only flat-keyed file shown in the non-root cgroups.
+ The sgx_epc resource will show the current active EPC memory
+ usage of the cgroup and its descendants. EPC pages that are
+ swapped out to backing RAM are not included in the current count.
+
+ misc.max
+ A read-write single value file which exists on non-root
+ cgroups. The sgx_epc resource will show the EPC usage
+ hard limit. The default is "max".
+
+ If a cgroup's EPC usage reaches this limit, EPC allocations,
+ e.g. for page fault handling, will be blocked until EPC can
+ be reclaimed from the cgroup. If EPC cannot be reclaimed in
+ a timely manner, reclaim will be forced, e.g. by ignoring LRU.
+
+ The EPC pages allocated for KVM guests by the virtual EPC driver
+ are not reclaimable by the host kernel SGX reclaimers. If a VMM
+ tries to start a VM within a cgroup whose EPC usage reaches this
+ limit, the virtual EPC driver will stop allocating more EPC for the
+ VM, and return SIGBUS to the VMM which would abort the VM launch.
+
+ misc.events
+ A read-only flat-keyed file which exists on non-root cgroups.
+ A value change in this file generates a file modified event.
+
+ max
+ The number of times the cgroup has triggered a reclaim
+ due to its EPC usage approaching (or exceeding) its max
+ EPC boundary.
+
+Migration
+---------
+
+Once an EPC page is charged to a cgroup (during allocation), it
+remains charged to the original cgroup until the page is released
+or reclaimed. Migrating a process to a different cgroup doesn't
+move the EPC charges that it incurred while in the previous cgroup
+to its new cgroup.
--
2.25.1
next prev parent reply other threads:[~2023-09-23 3:08 UTC|newest]
Thread overview: 119+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-23 3:06 [PATCH v5 00/18] Add Cgroup support for SGX EPC memory Haitao Huang
2023-09-23 3:06 ` [PATCH v5 01/18] cgroup/misc: Add per resource callbacks for CSS events Haitao Huang
2023-09-25 17:09 ` Jarkko Sakkinen
2023-09-26 3:04 ` Haitao Huang
2023-09-26 13:10 ` Jarkko Sakkinen
2023-09-26 13:13 ` Jarkko Sakkinen
2023-09-27 1:56 ` Haitao Huang
2023-10-02 22:47 ` Jarkko Sakkinen
2023-10-02 22:55 ` Jarkko Sakkinen
2023-10-04 15:45 ` Haitao Huang
2023-10-04 17:18 ` Tejun Heo
2023-09-27 9:20 ` Huang, Kai
2023-10-03 14:29 ` Haitao Huang
2023-10-17 18:55 ` Michal Koutný
2023-09-23 3:06 ` [PATCH v5 02/18] cgroup/misc: Add SGX EPC resource type and export APIs for SGX driver Haitao Huang
2023-09-25 18:50 ` Tejun Heo
2023-09-28 3:59 ` Huang, Kai
2023-10-03 7:00 ` Haitao Huang
2023-10-03 19:33 ` Huang, Kai
2023-09-23 3:06 ` [PATCH v5 03/18] x86/sgx: Add sgx_epc_lru_lists to encapsulate LRU lists Haitao Huang
2023-09-23 3:06 ` [PATCH v5 04/18] x86/sgx: Use sgx_epc_lru_lists for existing active page list Haitao Huang
2023-09-23 3:06 ` [PATCH v5 05/18] x86/sgx: Store reclaimable EPC pages in sgx_epc_lru_lists Haitao Huang
2023-09-27 10:14 ` Huang, Kai
2023-09-23 3:06 ` [PATCH v5 06/18] x86/sgx: Introduce EPC page states Haitao Huang
2023-09-25 17:11 ` Jarkko Sakkinen
2023-09-27 10:28 ` Huang, Kai
2023-10-03 4:49 ` Haitao Huang
2023-10-03 20:03 ` Huang, Kai
2023-10-04 15:24 ` Haitao Huang
2023-10-04 21:05 ` Huang, Kai
2023-09-23 3:06 ` [PATCH v5 07/18] x86/sgx: Introduce RECLAIM_IN_PROGRESS state Haitao Huang
2023-09-25 17:13 ` Jarkko Sakkinen
2023-09-27 10:42 ` Huang, Kai
2023-09-23 3:06 ` [PATCH v5 08/18] x86/sgx: Use a list to track to-be-reclaimed pages Haitao Huang
2023-09-28 9:28 ` Huang, Kai
2023-10-03 5:09 ` Haitao Huang
2023-09-23 3:06 ` [PATCH v5 09/18] x86/sgx: Store struct sgx_encl when allocating new VA pages Haitao Huang
2023-09-27 11:14 ` Huang, Kai
2023-09-27 15:35 ` Haitao Huang
2023-09-27 21:21 ` Huang, Kai
2023-09-29 15:06 ` Haitao Huang
2023-10-02 11:05 ` Huang, Kai
2023-09-27 11:35 ` Huang, Kai
2023-10-03 6:45 ` Haitao Huang
2023-10-03 20:07 ` Huang, Kai
2023-10-04 15:03 ` Haitao Huang
2023-10-04 21:13 ` Huang, Kai
2023-10-05 4:22 ` Haitao Huang
2023-10-05 6:49 ` Huang, Kai
2023-09-23 3:06 ` [PATCH v5 10/18] x86/sgx: Add EPC page flags to identify owner types Haitao Huang
2023-09-23 3:06 ` [PATCH v5 11/18] x86/sgx: store unreclaimable pages in LRU lists Haitao Huang
2023-09-27 11:57 ` Huang, Kai
2023-10-03 5:42 ` Haitao Huang
2023-09-28 9:41 ` Huang, Kai
2023-10-03 5:15 ` Haitao Huang
2023-10-03 20:12 ` Huang, Kai
2023-09-23 3:06 ` [PATCH v5 12/18] x86/sgx: Add EPC OOM path to forcefully reclaim EPC Haitao Huang
2023-10-09 23:45 ` Huang, Kai
2023-10-10 0:23 ` Sean Christopherson
2023-10-10 0:50 ` Huang, Kai
2023-10-10 1:34 ` Huang, Kai
2023-10-10 16:49 ` Haitao Huang
2023-10-11 0:51 ` Huang, Kai
2023-10-12 13:27 ` Haitao Huang
2023-10-16 10:57 ` Huang, Kai
2023-10-16 19:52 ` Haitao Huang
2023-10-16 21:09 ` Huang, Kai
2023-10-17 0:10 ` Haitao Huang
2023-10-17 1:34 ` Huang, Kai
2023-10-17 12:58 ` Haitao Huang
2023-10-17 18:54 ` Michal Koutný
2023-10-17 19:13 ` Michal Koutný
2023-10-18 4:39 ` Haitao Huang
2023-10-18 4:37 ` Haitao Huang
2023-10-18 13:55 ` Dave Hansen
2023-10-18 15:26 ` Haitao Huang
2023-10-18 15:37 ` Dave Hansen
2023-10-18 15:52 ` Michal Koutný
2023-10-18 16:25 ` Haitao Huang
2023-10-16 21:32 ` Sean Christopherson
2023-10-17 0:09 ` Haitao Huang
2023-10-17 15:43 ` Sean Christopherson
2023-10-17 11:49 ` Mikko Ylinen
2023-10-11 1:14 ` Huang, Kai
2023-10-16 11:02 ` Huang, Kai
2023-10-10 1:42 ` Haitao Huang
2023-10-10 2:23 ` Huang, Kai
2023-10-10 13:26 ` Haitao Huang
2023-10-11 0:01 ` Sean Christopherson
2023-10-11 15:02 ` Haitao Huang
2023-10-10 1:04 ` Haitao Huang
2023-10-10 1:18 ` Huang, Kai
2023-10-10 1:38 ` Haitao Huang
2023-10-10 2:12 ` Huang, Kai
2023-10-10 17:05 ` Haitao Huang
2023-10-11 0:31 ` Huang, Kai
2023-10-11 16:04 ` Haitao Huang
2023-09-23 3:06 ` [PATCH v5 13/18] x86/sgx: Expose sgx_reclaim_pages() for use by EPC cgroup Haitao Huang
2023-10-05 12:24 ` Huang, Kai
2023-10-05 19:23 ` Haitao Huang
2023-10-05 20:25 ` Huang, Kai
2023-09-23 3:06 ` [PATCH v5 14/18] x86/sgx: Add helper to grab pages from an arbitrary EPC LRU Haitao Huang
2023-09-23 3:06 ` [PATCH v5 15/18] x86/sgx: Prepare for multiple LRUs Haitao Huang
2023-10-05 12:30 ` Huang, Kai
2023-10-05 19:33 ` Haitao Huang
2023-10-05 20:38 ` Huang, Kai
2023-09-23 3:06 ` [PATCH v5 16/18] x86/sgx: Limit process EPC usage with misc cgroup controller Haitao Huang
2023-09-25 17:15 ` Jarkko Sakkinen
2023-10-05 21:01 ` Huang, Kai
2023-10-10 0:12 ` Huang, Kai
2023-10-10 0:16 ` Huang, Kai
2023-10-10 0:26 ` Huang, Kai
2023-10-22 18:26 ` Haitao Huang
2023-10-10 9:19 ` Huang, Kai
2023-10-10 9:32 ` Huang, Kai
2023-10-17 18:54 ` Michal Koutný
2023-10-19 16:05 ` Haitao Huang
2023-09-23 3:06 ` Haitao Huang [this message]
2023-09-23 3:06 ` [PATCH v5 18/18] selftests/sgx: Add scripts for EPC cgroup testing Haitao Huang
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