Documentation of Encryption IDs controller. This new controller is used
to track and limit usage of hardware memory encryption capabilities on
the CPUs.
Signed-off-by: Vipin Sharma <vipinsh@xxxxxxxxxx>
Reviewed-by: David Rientjes <rientjes@xxxxxxxxxx>
Reviewed-by: Dionna Glaze <dionnaglaze@xxxxxxxxxx>
---
.../admin-guide/cgroup-v1/encryption_ids.rst | 1 +
Documentation/admin-guide/cgroup-v2.rst | 78 ++++++++++++++++++-
2 files changed, 77 insertions(+), 2 deletions(-)
create mode 100644 Documentation/admin-guide/cgroup-v1/encryption_ids.rst
diff --git a/Documentation/admin-guide/cgroup-v1/encryption_ids.rst b/Documentation/admin-guide/cgroup-v1/encryption_ids.rst
new file mode 100644
index 000000000000..8e9e9311daeb
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v1/encryption_ids.rst
@@ -0,0 +1 @@
+/Documentation/admin-guide/cgroup-v2.rst
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 63521cd36ce5..72993571de2e 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -63,8 +63,11 @@ v1 is available under :ref:`Documentation/admin-guide/cgroup-v1/index.rst <cgrou
5-7-1. RDMA Interface Files
5-8. HugeTLB
5.8-1. HugeTLB Interface Files
- 5-8. Misc
- 5-8-1. perf_event
+ 5-9. Encryption IDs
+ 5.9-1 Encryption IDs Interface Files
+ 5.9-2 Migration and Ownership
+ 5-10. Misc
+ 5-10-1. perf_event
5-N. Non-normative information
5-N-1. CPU controller root cgroup process behaviour
5-N-2. IO controller root cgroup process behaviour
@@ -2160,6 +2163,77 @@ HugeTLB Interface Files
are local to the cgroup i.e. not hierarchical. The file modified event
generated on this file reflects only the local events.
+Encryption IDs
+--------------
+
+There are multiple hardware memory encryption capabilities provided by the
+hardware vendors, like Secure Encrypted Virtualization (SEV) and SEV Encrypted
+State (SEV-ES) from AMD.
+
+These features are being used in encrypting virtual machines (VMs) and user
+space programs. However, only a small number of keys/IDs can be used
+simultaneously.
+
+This limited availability of these IDs requires system admin to optimize
+allocation, control, and track the usage of the resources in the cloud
+infrastructure. This resource also needs to be protected from getting exhausted
+by some malicious program and causing starvation for other programs.
+
+Encryption IDs controller provides capability to register the resource for
+controlling and tracking through the cgroups.
+
+Encryption IDs Interface Files
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Each encryption ID type have their own interface files,
+encids.[ID TYPE].{max, current, stat}, where "ID TYPE" can be sev and
+sev-es.
+
+ encids.[ID TYPE].stat
+ A read-only flat-keyed single value file. This file exists only in the
+ root cgroup.
+
+ It shows the total number of encryption IDs available and currently in
+ use on the platform::
+ # cat encids.sev.stat
+ total 509
+ used 0
+
+ encids.[ID TYPE].max
+ A read-write file which exists on the non-root cgroups. File is used to
+ set maximum count of "[ID TYPE]" which can be used in the cgroup.
+
+ Limit can be set to max by::
+ # echo max > encids.sev.max
+
+ Limit can be set by::
+ # echo 100 > encids.sev.max
+
+ This file shows the max limit of the encryption ID in the cgroup::
+ # cat encids.sev.max
+ max
+
+ OR::
+ # cat encids.sev.max
+ 100
+
+ Limits can be set more than the "total" capacity value in the
+ encids.[ID TYPE].stat file, however, the controller ensures
+ that the usage never exceeds the "total" and the max limit.
+
+ encids.[ID TYPE].current
+ A read-only single value file which exists on non-root cgroups.
+
+ Shows the total number of encrypted IDs being used in the cgroup.
+
+Migration and Ownership
+~~~~~~~~~~~~~~~~~~~~~~~
+
+An encryption ID is charged to the cgroup in which it is used first, and
+stays charged to that cgroup until that ID is freed. Migrating a process
+to a different cgroup do not move the charge to the destination cgroup
+where the process has moved.
+
Misc
----
--
2.30.0.284.gd98b1dd5eaa7-goog
