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, 16 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/debugfs-olpc b/Documentation/ABI/testing/debugfs-olpc
new file mode 100644
index 000000000..bd76cc6d5
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-olpc
@@ -0,0 +1,16 @@
+What:		/sys/kernel/debug/olpc-ec/cmd
+Date:		Dec 2011
+KernelVersion:	3.4
+Contact:	devel@lists.laptop.org
+Description:
+
+A generic interface for executing OLPC Embedded Controller commands and
+reading their responses.
+
+To execute a command, write data with the format: CC:N A A A A
+CC is the (hex) command, N is the count of expected reply bytes, and A A A A
+are optional (hex) arguments.
+
+To read the response (if any), read from the generic node after executing
+a command. Hex reply bytes will be returned, *whether or not* they came from
+the immediately previous command.