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, 10 insertions, 0 deletions

diff --git a/drivers/net/phy/stubs.c b/drivers/net/phy/stubs.c
new file mode 100644
index 000000000..cfb9f275e
--- /dev/null
+++ b/drivers/net/phy/stubs.c
@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Stubs for PHY library functionality called by the core network stack.
+ * These are necessary because CONFIG_PHYLIB can be a module, and built-in
+ * code cannot directly call symbols exported by modules.
+ */
+#include <linux/phylib_stubs.h>
+
+const struct phylib_stubs *phylib_stubs;
+EXPORT_SYMBOL_GPL(phylib_stubs);