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, 148 insertions, 0 deletions

diff --git a/include/trace/events/migrate.h b/include/trace/events/migrate.h
new file mode 100644
index 000000000..15ee2ef20
--- /dev/null
+++ b/include/trace/events/migrate.h
@@ -0,0 +1,148 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM migrate
+
+#if !defined(_TRACE_MIGRATE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_MIGRATE_H
+
+#include <linux/tracepoint.h>
+
+#define MIGRATE_MODE						\
+	EM( MIGRATE_ASYNC,	"MIGRATE_ASYNC")		\
+	EM( MIGRATE_SYNC_LIGHT,	"MIGRATE_SYNC_LIGHT")		\
+	EMe(MIGRATE_SYNC,	"MIGRATE_SYNC")
+
+
+#define MIGRATE_REASON						\
+	EM( MR_COMPACTION,	"compaction")			\
+	EM( MR_MEMORY_FAILURE,	"memory_failure")		\
+	EM( MR_MEMORY_HOTPLUG,	"memory_hotplug")		\
+	EM( MR_SYSCALL,		"syscall_or_cpuset")		\
+	EM( MR_MEMPOLICY_MBIND,	"mempolicy_mbind")		\
+	EM( MR_NUMA_MISPLACED,	"numa_misplaced")		\
+	EM( MR_CONTIG_RANGE,	"contig_range")			\
+	EM( MR_LONGTERM_PIN,	"longterm_pin")			\
+	EM( MR_DEMOTION,	"demotion")			\
+	EM( MR_DAMON,		"damon")			\
+	EMe(MR_NEVER,		"never_migrated")
+
+/*
+ * First define the enums in the above macros to be exported to userspace
+ * via TRACE_DEFINE_ENUM().
+ */
+#undef EM
+#undef EMe
+#define EM(a, b)	TRACE_DEFINE_ENUM(a);
+#define EMe(a, b)	TRACE_DEFINE_ENUM(a);
+
+MIGRATE_MODE
+MIGRATE_REASON
+
+/*
+ * Now redefine the EM() and EMe() macros to map the enums to the strings
+ * that will be printed in the output.
+ */
+#undef EM
+#undef EMe
+#define EM(a, b)	{a, b},
+#define EMe(a, b)	{a, b}
+
+TRACE_EVENT(mm_migrate_pages,
+
+	TP_PROTO(unsigned long succeeded, unsigned long failed,
+		 unsigned long thp_succeeded, unsigned long thp_failed,
+		 unsigned long thp_split, unsigned long large_folio_split,
+		 enum migrate_mode mode, enum migrate_reason reason),
+
+	TP_ARGS(succeeded, failed, thp_succeeded, thp_failed,
+		thp_split, large_folio_split, mode, reason),
+
+	TP_STRUCT__entry(
+		__field(	unsigned long,		succeeded)
+		__field(	unsigned long,		failed)
+		__field(	unsigned long,		thp_succeeded)
+		__field(	unsigned long,		thp_failed)
+		__field(	unsigned long,		thp_split)
+		__field(	unsigned long,		large_folio_split)
+		__field(	enum migrate_mode,	mode)
+		__field(	enum migrate_reason,	reason)
+	),
+
+	TP_fast_assign(
+		__entry->succeeded			= succeeded;
+		__entry->failed				= failed;
+		__entry->thp_succeeded		= thp_succeeded;
+		__entry->thp_failed			= thp_failed;
+		__entry->thp_split			= thp_split;
+		__entry->large_folio_split	= large_folio_split;
+		__entry->mode				= mode;
+		__entry->reason				= reason;
+	),
+
+	TP_printk("nr_succeeded=%lu nr_failed=%lu nr_thp_succeeded=%lu nr_thp_failed=%lu nr_thp_split=%lu nr_split=%lu mode=%s reason=%s",
+		__entry->succeeded,
+		__entry->failed,
+		__entry->thp_succeeded,
+		__entry->thp_failed,
+		__entry->thp_split,
+		__entry->large_folio_split,
+		__print_symbolic(__entry->mode, MIGRATE_MODE),
+		__print_symbolic(__entry->reason, MIGRATE_REASON))
+);
+
+TRACE_EVENT(mm_migrate_pages_start,
+
+	TP_PROTO(enum migrate_mode mode, enum migrate_reason reason),
+
+	TP_ARGS(mode, reason),
+
+	TP_STRUCT__entry(
+		__field(enum migrate_mode, mode)
+		__field(enum migrate_reason, reason)
+	),
+
+	TP_fast_assign(
+		__entry->mode	= mode;
+		__entry->reason	= reason;
+	),
+
+	TP_printk("mode=%s reason=%s",
+		  __print_symbolic(__entry->mode, MIGRATE_MODE),
+		  __print_symbolic(__entry->reason, MIGRATE_REASON))
+);
+
+DECLARE_EVENT_CLASS(migration_pte,
+
+		TP_PROTO(unsigned long addr, unsigned long pte, int order),
+
+		TP_ARGS(addr, pte, order),
+
+		TP_STRUCT__entry(
+			__field(unsigned long, addr)
+			__field(unsigned long, pte)
+			__field(int, order)
+		),
+
+		TP_fast_assign(
+			__entry->addr = addr;
+			__entry->pte = pte;
+			__entry->order = order;
+		),
+
+		TP_printk("addr=%lx, pte=%lx order=%d", __entry->addr, __entry->pte, __entry->order)
+);
+
+DEFINE_EVENT(migration_pte, set_migration_pte,
+	TP_PROTO(unsigned long addr, unsigned long pte, int order),
+	TP_ARGS(addr, pte, order)
+);
+
+DEFINE_EVENT(migration_pte, remove_migration_pte,
+	TP_PROTO(unsigned long addr, unsigned long pte, int order),
+	TP_ARGS(addr, pte, order)
+);
+
+#endif /* _TRACE_MIGRATE_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>