linux-kernel - [RFC 2/2] cgroup: sev: Miscellaneous cgroup documentation.

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Message-Id: <20210218195549.1696769-3-vipinsh@google.com>
Date:   Thu, 18 Feb 2021 11:55:49 -0800
From:   Vipin Sharma <vipinsh@...gle.com>
To:     tj@...nel.org, thomas.lendacky@....com, brijesh.singh@....com,
        jon.grimm@....com, eric.vantassell@....com, pbonzini@...hat.com,
        hannes@...xchg.org, frankja@...ux.ibm.com, borntraeger@...ibm.com
Cc:     corbet@....net, seanjc@...gle.com, vkuznets@...hat.com,
        wanpengli@...cent.com, jmattson@...gle.com, joro@...tes.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        gingell@...gle.com, rientjes@...gle.com, dionnaglaze@...gle.com,
        kvm@...r.kernel.org, x86@...nel.org, cgroups@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Vipin Sharma <vipinsh@...gle.com>
Subject: [RFC 2/2] cgroup: sev: Miscellaneous cgroup documentation.

Documentation of miscellaneous cgroup controller. This new controller is
used to track and limit usage of scalar resources.

Signed-off-by: Vipin Sharma <vipinsh@...gle.com>
Reviewed-by: David Rientjes <rientjes@...gle.com>
---
 Documentation/admin-guide/cgroup-v1/misc.rst |  1 +
 Documentation/admin-guide/cgroup-v2.rst      | 64 +++++++++++++++++++-
 2 files changed, 63 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/admin-guide/cgroup-v1/misc.rst

diff --git a/Documentation/admin-guide/cgroup-v1/misc.rst b/Documentation/admin-guide/cgroup-v1/misc.rst
new file mode 100644
index 000000000000..8e9e9311daeb
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v1/misc.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 1de8695c264b..1a41a3623b9b 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. Misc
+       5.9-1 Miscellaneous cgroup Interface Files
+       5.9-2 Migration and Ownership
+     5-10. Others
+       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
@@ -2161,6 +2164,63 @@ HugeTLB Interface Files
 	generated on this file reflects only the local events.
 
 Misc
+--------------
+
+The Miscellaneous cgroup provides the resource allocation and tracking
+mechanism for the scalar resources which cannot be abstracted like the other
+cgroup resources. Controller is enabled by the CONFIG_CGROUP_MISC config
+option.
+
+The first two resources added to the miscellaneous controller are Secure
+Encrypted Virtualization (SEV) ASIDs and SEV - Encrypted State (SEV-ES) ASIDs.
+These limited ASIDs are used for encrypting virtual machines memory on the AMD
+platform.
+
+Misc Interface Files
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Miscellaneous controller provides 3 interface files:
+
+  misc.capacity
+        A read-only flat-keyed file shown only in the root cgroup.  It shows
+        miscellaneous scalar resources available on the platform along with
+        their quantities::
+	  $ cat misc.capacity
+	  sev 50
+	  sev_es 10
+
+  misc.current
+        A read-only flat-keyed file shown in the non-root cgroups.  It shows
+        the current usage of the resources in the cgroup and its children.::
+	  $ cat misc.current
+	  sev 3
+	  sev_es 0
+
+  misc.max
+        A read-write flat-keyed file shown in the non root cgroups. Allowed
+        maximum usage of the resources in the cgroup and its children.::
+	  $ cat misc.max
+	  sev max
+	  sev_es 4
+
+	Limit can be set by::
+	  # echo sev 1 > misc.max
+
+	Limit can be set to max by::
+	  # echo sev max > misc.max
+
+        Limits can be set more than the capacity value in the misc.capacity
+        file.
+
+Migration and Ownership
+~~~~~~~~~~~~~~~~~~~~~~~
+
+A miscellaneous scalar resource is charged to the cgroup in which it is used
+first, and stays charged to that cgroup until that resource is freed. Migrating
+a process to a different cgroup do not move the charge to the destination
+cgroup where the process has moved.
+
+Others
 ----
 
 perf_event
-- 
2.30.0.617.g56c4b15f3c-goog