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, 204 insertions, 0 deletions

diff --git a/include/trace/events/qdisc.h b/include/trace/events/qdisc.h
new file mode 100644
index 000000000..d8a5c2677
--- /dev/null
+++ b/include/trace/events/qdisc.h
@@ -0,0 +1,204 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM qdisc
+
+#if !defined(_TRACE_QDISC_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_QDISC_H
+
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+#include <linux/tracepoint.h>
+#include <linux/ftrace.h>
+#include <linux/pkt_sched.h>
+#include <net/sch_generic.h>
+
+TRACE_EVENT(qdisc_dequeue,
+
+	TP_PROTO(struct Qdisc *qdisc, const struct netdev_queue *txq,
+		 int packets, struct sk_buff *skb),
+
+	TP_ARGS(qdisc, txq, packets, skb),
+
+	TP_STRUCT__entry(
+		__field(	struct Qdisc *,		qdisc	)
+		__field(const	struct netdev_queue *,	txq	)
+		__field(	int,			packets	)
+		__field(	void *,			skbaddr	)
+		__field(	int,			ifindex	)
+		__field(	u32,			handle	)
+		__field(	u32,			parent	)
+		__field(	unsigned long,		txq_state)
+	),
+
+	/* skb==NULL indicate packets dequeued was 0, even when packets==1 */
+	TP_fast_assign(
+		__entry->qdisc		= qdisc;
+		__entry->txq		= txq;
+		__entry->packets	= skb ? packets : 0;
+		__entry->skbaddr	= skb;
+		__entry->ifindex	= txq->dev ? txq->dev->ifindex : 0;
+		__entry->handle		= qdisc->handle;
+		__entry->parent		= qdisc->parent;
+		__entry->txq_state	= txq->state;
+	),
+
+	TP_printk("dequeue ifindex=%d qdisc handle=0x%X parent=0x%X txq_state=0x%lX packets=%d skbaddr=%p",
+		  __entry->ifindex, __entry->handle, __entry->parent,
+		  __entry->txq_state, __entry->packets, __entry->skbaddr )
+);
+
+TRACE_EVENT(qdisc_enqueue,
+
+	TP_PROTO(struct Qdisc *qdisc, const struct netdev_queue *txq, struct sk_buff *skb),
+
+	TP_ARGS(qdisc, txq, skb),
+
+	TP_STRUCT__entry(
+		__field(struct Qdisc *, qdisc)
+		__field(const struct netdev_queue *, txq)
+		__field(void *,	skbaddr)
+		__field(int, ifindex)
+		__field(u32, handle)
+		__field(u32, parent)
+	),
+
+	TP_fast_assign(
+		__entry->qdisc = qdisc;
+		__entry->txq	 = txq;
+		__entry->skbaddr = skb;
+		__entry->ifindex = txq->dev ? txq->dev->ifindex : 0;
+		__entry->handle	 = qdisc->handle;
+		__entry->parent	 = qdisc->parent;
+	),
+
+	TP_printk("enqueue ifindex=%d qdisc handle=0x%X parent=0x%X skbaddr=%p",
+		  __entry->ifindex, __entry->handle, __entry->parent, __entry->skbaddr)
+);
+
+#undef FN
+#undef FNe
+#define FN(reason)	TRACE_DEFINE_ENUM(QDISC_DROP_##reason);
+#define FNe(reason)	TRACE_DEFINE_ENUM(QDISC_DROP_##reason);
+DEFINE_QDISC_DROP_REASON(FN, FNe)
+
+#undef FN
+#undef FNe
+#define FN(reason)	{ QDISC_DROP_##reason, #reason },
+#define FNe(reason)	{ QDISC_DROP_##reason, #reason }
+
+TRACE_EVENT(qdisc_drop,
+
+	TP_PROTO(struct Qdisc *qdisc, const struct netdev_queue *txq,
+		 struct net_device *dev, struct sk_buff *skb,
+		 enum qdisc_drop_reason reason),
+
+	TP_ARGS(qdisc, txq, dev, skb, reason),
+
+	TP_STRUCT__entry(
+		__field(struct Qdisc *, qdisc)
+		__field(const struct netdev_queue *, txq)
+		__field(void *,	skbaddr)
+		__field(int, ifindex)
+		__field(u32, handle)
+		__field(u32, parent)
+		__field(enum qdisc_drop_reason, reason)
+		__string(kind, qdisc->ops->id)
+	),
+
+	TP_fast_assign(
+		__entry->qdisc = qdisc;
+		__entry->txq	 = txq;
+		__entry->skbaddr = skb;
+		__entry->ifindex = dev ? dev->ifindex : 0;
+		__entry->handle	 = qdisc->handle;
+		__entry->parent	 = qdisc->parent;
+		__entry->reason	 = reason;
+		__assign_str(kind);
+	),
+
+	TP_printk("drop ifindex=%d kind=%s handle=0x%X parent=0x%X skbaddr=%p reason=%s",
+		  __entry->ifindex, __get_str(kind), __entry->handle,
+		  __entry->parent, __entry->skbaddr,
+		  __print_symbolic(__entry->reason,
+				   DEFINE_QDISC_DROP_REASON(FN, FNe)))
+);
+
+#undef FN
+#undef FNe
+
+TRACE_EVENT(qdisc_reset,
+
+	TP_PROTO(struct Qdisc *q),
+
+	TP_ARGS(q),
+
+	TP_STRUCT__entry(
+		__string(	dev,		qdisc_dev(q) ? qdisc_dev(q)->name : "(null)"	)
+		__string(	kind,		q->ops->id		)
+		__field(	u32,		parent			)
+		__field(	u32,		handle			)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev);
+		__assign_str(kind);
+		__entry->parent = q->parent;
+		__entry->handle = q->handle;
+	),
+
+	TP_printk("dev=%s kind=%s parent=%x:%x handle=%x:%x", __get_str(dev),
+		  __get_str(kind), TC_H_MAJ(__entry->parent) >> 16, TC_H_MIN(__entry->parent),
+		  TC_H_MAJ(__entry->handle) >> 16, TC_H_MIN(__entry->handle))
+);
+
+TRACE_EVENT(qdisc_destroy,
+
+	TP_PROTO(struct Qdisc *q),
+
+	TP_ARGS(q),
+
+	TP_STRUCT__entry(
+		__string(	dev,		qdisc_dev(q)->name	)
+		__string(	kind,		q->ops->id		)
+		__field(	u32,		parent			)
+		__field(	u32,		handle			)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev);
+		__assign_str(kind);
+		__entry->parent = q->parent;
+		__entry->handle = q->handle;
+	),
+
+	TP_printk("dev=%s kind=%s parent=%x:%x handle=%x:%x", __get_str(dev),
+		  __get_str(kind), TC_H_MAJ(__entry->parent) >> 16, TC_H_MIN(__entry->parent),
+		  TC_H_MAJ(__entry->handle) >> 16, TC_H_MIN(__entry->handle))
+);
+
+TRACE_EVENT(qdisc_create,
+
+	TP_PROTO(const struct Qdisc_ops *ops, struct net_device *dev, u32 parent),
+
+	TP_ARGS(ops, dev, parent),
+
+	TP_STRUCT__entry(
+		__string(	dev,		dev->name	)
+		__string(	kind,		ops->id		)
+		__field(	u32,		parent		)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev);
+		__assign_str(kind);
+		__entry->parent = parent;
+	),
+
+	TP_printk("dev=%s kind=%s parent=%x:%x",
+		  __get_str(dev), __get_str(kind),
+		  TC_H_MAJ(__entry->parent) >> 16, TC_H_MIN(__entry->parent))
+);
+
+#endif /* _TRACE_QDISC_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>