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, 18 insertions, 0 deletions

diff --git a/drivers/net/arcnet/com9026.h b/drivers/net/arcnet/com9026.h
new file mode 100644
index 000000000..6adbc1871
--- /dev/null
+++ b/drivers/net/arcnet/com9026.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __COM9026_H
+#define __COM9026_H
+
+/* COM 9026 controller chip --> ARCnet register addresses */
+
+#define COM9026_REG_W_INTMASK	0	/* writable */
+#define COM9026_REG_R_STATUS	0	/* readable */
+#define COM9026_REG_W_COMMAND	1	/* writable, returns random vals on read (?) */
+#define COM9026_REG_RW_CONFIG	2	/* Configuration register */
+#define COM9026_REG_R_RESET	8	/* software reset (on read) */
+#define COM9026_REG_RW_MEMDATA	12	/* Data port for IO-mapped memory */
+#define COM9026_REG_W_ADDR_LO	14	/* Control registers for said */
+#define COM9026_REG_W_ADDR_HI	15
+
+#define COM9026_REG_R_STATION	1	/* Station ID */
+
+#endif