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, 66 insertions, 0 deletions

diff --git a/drivers/md/dm-audit.h b/drivers/md/dm-audit.h
new file mode 100644
index 000000000..2385f2b65
--- /dev/null
+++ b/drivers/md/dm-audit.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Creating audit records for mapped devices.
+ *
+ * Copyright (C) 2021 Fraunhofer AISEC. All rights reserved.
+ *
+ * Authors: Michael Weiß <michael.weiss@aisec.fraunhofer.de>
+ */
+
+#ifndef DM_AUDIT_H
+#define DM_AUDIT_H
+
+#include <linux/device-mapper.h>
+#include <linux/audit.h>
+
+#ifdef CONFIG_DM_AUDIT
+void dm_audit_log_bio(const char *dm_msg_prefix, const char *op,
+		      struct bio *bio, sector_t sector, int result);
+
+/*
+ * dm_audit_log_ti() is not intended to be used directly in dm modules,
+ * the wrapper functions below should be called by dm modules instead.
+ */
+void dm_audit_log_ti(int audit_type, const char *dm_msg_prefix, const char *op,
+		     struct dm_target *ti, int result);
+
+static inline void dm_audit_log_ctr(const char *dm_msg_prefix,
+				    struct dm_target *ti, int result)
+{
+	dm_audit_log_ti(AUDIT_DM_CTRL, dm_msg_prefix, "ctr", ti, result);
+}
+
+static inline void dm_audit_log_dtr(const char *dm_msg_prefix,
+				    struct dm_target *ti, int result)
+{
+	dm_audit_log_ti(AUDIT_DM_CTRL, dm_msg_prefix, "dtr", ti, result);
+}
+
+static inline void dm_audit_log_target(const char *dm_msg_prefix, const char *op,
+				       struct dm_target *ti, int result)
+{
+	dm_audit_log_ti(AUDIT_DM_EVENT, dm_msg_prefix, op, ti, result);
+}
+#else
+static inline void dm_audit_log_bio(const char *dm_msg_prefix, const char *op,
+				    struct bio *bio, sector_t sector,
+				    int result)
+{
+}
+static inline void dm_audit_log_target(const char *dm_msg_prefix,
+				       const char *op, struct dm_target *ti,
+				       int result)
+{
+}
+static inline void dm_audit_log_ctr(const char *dm_msg_prefix,
+				    struct dm_target *ti, int result)
+{
+}
+
+static inline void dm_audit_log_dtr(const char *dm_msg_prefix,
+				    struct dm_target *ti, int result)
+{
+}
+#endif
+
+#endif