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, 35 insertions, 0 deletions

diff --git a/scripts/jobserver-exec b/scripts/jobserver-exec
new file mode 100755
index 000000000..21b319e6c
--- /dev/null
+++ b/scripts/jobserver-exec
@@ -0,0 +1,35 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0+
+
+"""
+Determines how many parallel tasks "make" is expecting, as it is
+not exposed via any special variables, reserves them all, runs a subprocess
+with PARALLELISM environment variable set, and releases the jobs back again.
+
+See:
+    https://www.gnu.org/software/make/manual/html_node/POSIX-Jobserver.html#POSIX-Jobserver
+"""
+
+import os
+import sys
+
+LIB_DIR = "../tools/lib/python"
+SRC_DIR = os.path.dirname(os.path.realpath(__file__))
+
+sys.path.insert(0, os.path.join(SRC_DIR, LIB_DIR))
+
+from jobserver import JobserverExec                  # pylint: disable=C0415
+
+
+def main():
+    """Main program"""
+    if len(sys.argv) < 2:
+        name = os.path.basename(__file__)
+        sys.exit("usage: " + name +" command [args ...]\n" + __doc__)
+
+    with JobserverExec() as jobserver:
+        return jobserver.run(sys.argv[1:])
+
+
+if __name__ == "__main__":
+    sys.exit(main())