From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001
From: Zeng Chi <zengchi@kylinos.cn>
Date: Mon, 21 Sep 2026 18:24:42 +0800
Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL
 attributes

Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.

Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 Documentation/netlink/specs/nlctrl.yaml | 208 ++++++++++++++++++++++++++++++++
 1 file changed, 208 insertions(+)
 create mode 100644 Documentation/netlink/specs/nlctrl.yaml

(limited to 'Documentation/netlink/specs/nlctrl.yaml')

diff --git a/Documentation/netlink/specs/nlctrl.yaml b/Documentation/netlink/specs/nlctrl.yaml
new file mode 100644
index 000000000..8b4472a6a
--- /dev/null
+++ b/Documentation/netlink/specs/nlctrl.yaml
@@ -0,0 +1,208 @@
+# SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
+---
+name: nlctrl
+protocol: genetlink-legacy
+uapi-header: linux/genetlink.h
+
+doc: |
+  genetlink meta-family that exposes information about all genetlink
+  families registered in the kernel (including itself).
+
+definitions:
+  -
+    name: op-flags
+    type: flags
+    enum-name:
+    entries:
+      - admin-perm
+      - cmd-cap-do
+      - cmd-cap-dump
+      - cmd-cap-haspol
+      - uns-admin-perm
+  -
+    name: attr-type
+    enum-name: netlink-attribute-type
+    type: enum
+    entries:
+      - invalid
+      - flag
+      - u8
+      - u16
+      - u32
+      - u64
+      - s8
+      - s16
+      - s32
+      - s64
+      - binary
+      - string
+      - nul-string
+      - nested
+      - nested-array
+      - bitfield32
+      - sint
+      - uint
+
+attribute-sets:
+  -
+    name: ctrl-attrs
+    name-prefix: ctrl-attr-
+    attributes:
+      -
+        name: family-id
+        type: u16
+      -
+        name: family-name
+        type: string
+      -
+        name: version
+        type: u32
+      -
+        name: hdrsize
+        type: u32
+      -
+        name: maxattr
+        type: u32
+      -
+        name: ops
+        type: indexed-array
+        sub-type: nest
+        nested-attributes: op-attrs
+      -
+        name: mcast-groups
+        type: indexed-array
+        sub-type: nest
+        nested-attributes: mcast-group-attrs
+      -
+        name: policy
+        type: nest-type-value
+        type-value: [policy-id, attr-id]
+        nested-attributes: policy-attrs
+      -
+        name: op-policy
+        type: nest-type-value
+        type-value: [op-id]
+        nested-attributes: op-policy-attrs
+      -
+        name: op
+        type: u32
+  -
+    name: mcast-group-attrs
+    name-prefix: ctrl-attr-mcast-grp-
+    enum-name:
+    attributes:
+      -
+        name: name
+        type: string
+      -
+        name: id
+        type: u32
+  -
+    name: op-attrs
+    name-prefix: ctrl-attr-op-
+    enum-name:
+    attributes:
+      -
+        name: id
+        type: u32
+      -
+        name: flags
+        type: u32
+        enum: op-flags
+        enum-as-flags: true
+  -
+    name: policy-attrs
+    name-prefix: nl-policy-type-attr-
+    enum-name:
+    attributes:
+      -
+        name: type
+        type: u32
+        enum: attr-type
+      -
+        name: min-value-s
+        type: s64
+      -
+        name: max-value-s
+        type: s64
+      -
+        name: min-value-u
+        type: u64
+      -
+        name: max-value-u
+        type: u64
+      -
+        name: min-length
+        type: u32
+      -
+        name: max-length
+        type: u32
+      -
+        name: policy-idx
+        type: u32
+      -
+        name: policy-maxtype
+        type: u32
+      -
+        name: bitfield32-mask
+        type: u32
+      -
+        name: mask
+        type: u64
+      -
+        name: pad
+        type: pad
+  -
+    name: op-policy-attrs
+    name-prefix: ctrl-attr-policy-
+    enum-name:
+    attributes:
+      -
+        name: do
+        type: u32
+      -
+        name: dump
+        type: u32
+
+operations:
+  enum-model: directional
+  name-prefix: ctrl-cmd-
+  list:
+    -
+      name: getfamily
+      doc: Get / dump genetlink families
+      attribute-set: ctrl-attrs
+      do:
+        request:
+          value: 3
+          attributes:
+            - family-name
+        reply: &all-attrs
+          value: 1
+          attributes:
+            - family-id
+            - family-name
+            - hdrsize
+            - maxattr
+            - mcast-groups
+            - ops
+            - version
+      dump:
+        reply: *all-attrs
+    -
+      name: getpolicy
+      doc: Get / dump genetlink policies
+      attribute-set: ctrl-attrs
+      dump:
+        request:
+          value: 10
+          attributes:
+            - family-name
+            - family-id
+            - op
+        reply:
+          value: 10
+          attributes:
+            - family-id
+            - op-policy
+            - policy
-- 
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