KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted

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>

1 files changed, 192 insertions, 0 deletions

diff --git a/Documentation/admin-guide/index.rst b/Documentation/admin-guide/index.rst
new file mode 100644
index 000000000..cd28dfe91
--- /dev/null
+++ b/Documentation/admin-guide/index.rst
@@ -0,0 +1,192 @@
+=================================================
+The Linux kernel user's and administrator's guide
+=================================================
+
+The following is a collection of user-oriented documents that have been
+added to the kernel over time.  There is, as yet, little overall order or
+organization here — this material was not written to be a single, coherent
+document!  With luck things will improve quickly over time.
+
+General guides to kernel administration
+---------------------------------------
+
+This initial section contains overall information, including the README
+file describing the kernel as a whole, documentation on kernel parameters,
+etc.
+
+.. toctree::
+   :maxdepth: 1
+
+   README
+   devices
+
+   features
+
+A big part of the kernel's administrative interface is the /proc and sysfs
+virtual filesystems; these documents describe how to interact with tem
+
+.. toctree::
+   :maxdepth: 1
+
+   sysfs-rules
+   sysctl/index
+   cputopology
+   abi
+
+Security-related documentation:
+
+.. toctree::
+   :maxdepth: 1
+
+   hw-vuln/index
+   LSM/index
+   perf-security
+
+Booting the kernel
+------------------
+
+.. toctree::
+   :maxdepth: 1
+
+   bootconfig
+   kernel-parameters
+   efi-stub
+   initrd
+
+
+Tracking down and identifying problems
+--------------------------------------
+
+Here is a set of documents aimed at users who are trying to track down
+problems and bugs in particular.
+
+.. toctree::
+   :maxdepth: 1
+
+   reporting-issues
+   reporting-regressions
+   quickly-build-trimmed-linux
+   verify-bugs-and-bisect-regressions
+   bug-hunting
+   bug-bisect
+   tainted-kernels
+   ramoops
+   dynamic-debug-howto
+   init
+   kdump/index
+   perf/index
+   pstore-blk
+   clearing-warn-once
+   kernel-per-CPU-kthreads
+   lockup-watchdogs
+   RAS/index
+   sysrq
+
+
+Core-kernel subsystems
+----------------------
+
+These documents describe core-kernel administration interfaces that are
+likely to be of interest on almost any system.
+
+.. toctree::
+   :maxdepth: 1
+
+   cgroup-v2
+   cgroup-v1/index
+   cpu-isolation
+   cpu-load
+   mm/index
+   module-signing
+   namespaces/index
+   numastat
+   pm/index
+   syscall-user-dispatch
+
+Support for non-native binary formats.  Note that some of these
+documents are ... old ...
+
+.. toctree::
+   :maxdepth: 1
+
+   binfmt-misc
+   java
+   mono
+
+
+Block-layer and filesystem administration
+-----------------------------------------
+
+.. toctree::
+   :maxdepth: 1
+
+   bcache
+   binderfs
+   blockdev/index
+   cifs/index
+   device-mapper/index
+   ext4
+   filesystem-monitoring
+   nfs/index
+   iostats
+   jfs
+   md
+   ufs
+   xfs
+
+Device-specific guides
+----------------------
+
+How to configure your hardware within your Linux system.
+
+.. toctree::
+   :maxdepth: 1
+
+   acpi/index
+   aoe/index
+   auxdisplay/index
+   braille-console
+   btmrvl
+   dell_rbu
+   edid
+   gpio/index
+   hw_random
+   laptops/index
+   lcd-panel-cgram
+   media/index
+   nvme-multipath
+   parport
+   pnp
+   rapidio
+   rtc
+   serial-console
+   svga
+   thermal/index
+   thunderbolt
+   vga-softcursor
+   video-output
+
+Workload analysis
+-----------------
+
+This is the beginning of a section with information of interest to
+application developers and system integrators doing analysis of the
+Linux kernel for safety critical applications. Documents supporting
+analysis of kernel interactions with applications, and key kernel
+subsystems expectations will be found here.
+
+.. toctree::
+   :maxdepth: 1
+
+   workload-tracing
+
+Everything else
+---------------
+
+A few hard-to-categorize and generally obsolete documents.
+
+.. toctree::
+   :maxdepth: 1
+
+   ldm
+   unicode