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, 225 insertions, 0 deletions

diff --git a/include/trace/events/9p.h b/include/trace/events/9p.h
new file mode 100644
index 000000000..cd104a134
--- /dev/null
+++ b/include/trace/events/9p.h
@@ -0,0 +1,225 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM 9p
+
+#if !defined(_TRACE_9P_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_9P_H
+
+#include <linux/tracepoint.h>
+
+#define P9_MSG_T							\
+		EM( P9_TLERROR,		"P9_TLERROR" )			\
+		EM( P9_RLERROR,		"P9_RLERROR" )			\
+		EM( P9_TSTATFS,		"P9_TSTATFS" )			\
+		EM( P9_RSTATFS,		"P9_RSTATFS" )			\
+		EM( P9_TLOPEN,		"P9_TLOPEN" )			\
+		EM( P9_RLOPEN,		"P9_RLOPEN" )			\
+		EM( P9_TLCREATE,	"P9_TLCREATE" )			\
+		EM( P9_RLCREATE,	"P9_RLCREATE" )			\
+		EM( P9_TSYMLINK,	"P9_TSYMLINK" )			\
+		EM( P9_RSYMLINK,	"P9_RSYMLINK" )			\
+		EM( P9_TMKNOD,		"P9_TMKNOD" )			\
+		EM( P9_RMKNOD,		"P9_RMKNOD" )			\
+		EM( P9_TRENAME,		"P9_TRENAME" )			\
+		EM( P9_RRENAME,		"P9_RRENAME" )			\
+		EM( P9_TREADLINK,	"P9_TREADLINK" )		\
+		EM( P9_RREADLINK,	"P9_RREADLINK" )		\
+		EM( P9_TGETATTR,	"P9_TGETATTR" )			\
+		EM( P9_RGETATTR,	"P9_RGETATTR" )			\
+		EM( P9_TSETATTR,	"P9_TSETATTR" )			\
+		EM( P9_RSETATTR,	"P9_RSETATTR" )			\
+		EM( P9_TXATTRWALK,	"P9_TXATTRWALK" )		\
+		EM( P9_RXATTRWALK,	"P9_RXATTRWALK" )		\
+		EM( P9_TXATTRCREATE,	"P9_TXATTRCREATE" )		\
+		EM( P9_RXATTRCREATE,	"P9_RXATTRCREATE" )		\
+		EM( P9_TREADDIR,	"P9_TREADDIR" )			\
+		EM( P9_RREADDIR,	"P9_RREADDIR" )			\
+		EM( P9_TFSYNC,		"P9_TFSYNC" )			\
+		EM( P9_RFSYNC,		"P9_RFSYNC" )			\
+		EM( P9_TLOCK,		"P9_TLOCK" )			\
+		EM( P9_RLOCK,		"P9_RLOCK" )			\
+		EM( P9_TGETLOCK,	"P9_TGETLOCK" )			\
+		EM( P9_RGETLOCK,	"P9_RGETLOCK" )			\
+		EM( P9_TLINK,		"P9_TLINK" )			\
+		EM( P9_RLINK,		"P9_RLINK" )			\
+		EM( P9_TMKDIR,		"P9_TMKDIR" )			\
+		EM( P9_RMKDIR,		"P9_RMKDIR" )			\
+		EM( P9_TRENAMEAT,	"P9_TRENAMEAT" )		\
+		EM( P9_RRENAMEAT,	"P9_RRENAMEAT" )		\
+		EM( P9_TUNLINKAT,	"P9_TUNLINKAT" )		\
+		EM( P9_RUNLINKAT,	"P9_RUNLINKAT" )		\
+		EM( P9_TVERSION,	"P9_TVERSION" )			\
+		EM( P9_RVERSION,	"P9_RVERSION" )			\
+		EM( P9_TAUTH,		"P9_TAUTH" )			\
+		EM( P9_RAUTH,		"P9_RAUTH" )			\
+		EM( P9_TATTACH,		"P9_TATTACH" )			\
+		EM( P9_RATTACH,		"P9_RATTACH" )			\
+		EM( P9_TERROR,		"P9_TERROR" )			\
+		EM( P9_RERROR,		"P9_RERROR" )			\
+		EM( P9_TFLUSH,		"P9_TFLUSH" )			\
+		EM( P9_RFLUSH,		"P9_RFLUSH" )			\
+		EM( P9_TWALK,		"P9_TWALK" )			\
+		EM( P9_RWALK,		"P9_RWALK" )			\
+		EM( P9_TOPEN,		"P9_TOPEN" )			\
+		EM( P9_ROPEN,		"P9_ROPEN" )			\
+		EM( P9_TCREATE,		"P9_TCREATE" )			\
+		EM( P9_RCREATE,		"P9_RCREATE" )			\
+		EM( P9_TREAD,		"P9_TREAD" )			\
+		EM( P9_RREAD,		"P9_RREAD" )			\
+		EM( P9_TWRITE,		"P9_TWRITE" )			\
+		EM( P9_RWRITE,		"P9_RWRITE" )			\
+		EM( P9_TCLUNK,		"P9_TCLUNK" )			\
+		EM( P9_RCLUNK,		"P9_RCLUNK" )			\
+		EM( P9_TREMOVE,		"P9_TREMOVE" )			\
+		EM( P9_RREMOVE,		"P9_RREMOVE" )			\
+		EM( P9_TSTAT,		"P9_TSTAT" )			\
+		EM( P9_RSTAT,		"P9_RSTAT" )			\
+		EM( P9_TWSTAT,		"P9_TWSTAT" )			\
+		EMe(P9_RWSTAT,		"P9_RWSTAT" )
+
+
+#define P9_FID_REFTYPE							\
+		EM( P9_FID_REF_CREATE,	"create " )			\
+		EM( P9_FID_REF_GET,	"get    " )			\
+		EM( P9_FID_REF_PUT,	"put    " )			\
+		EMe(P9_FID_REF_DESTROY,	"destroy" )
+
+/* Define EM() to export the enums 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);
+
+P9_MSG_T
+P9_FID_REFTYPE
+
+/* And also use EM/EMe to define helper enums -- once */
+#ifndef __9P_DECLARE_TRACE_ENUMS_ONLY_ONCE
+#define __9P_DECLARE_TRACE_ENUMS_ONLY_ONCE
+#undef EM
+#undef EMe
+#define EM(a, b)	a,
+#define EMe(a, b)	a
+
+enum p9_fid_reftype {
+	P9_FID_REFTYPE
+} __mode(byte);
+
+#endif
+
+/*
+ * 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 }
+
+#define show_9p_op(type)						\
+	__print_symbolic(type, P9_MSG_T)
+#define show_9p_fid_reftype(type)					\
+	__print_symbolic(type, P9_FID_REFTYPE)
+
+TRACE_EVENT(9p_client_req,
+	    TP_PROTO(struct p9_client *clnt, int8_t type, int tag),
+
+	    TP_ARGS(clnt, type, tag),
+
+	    TP_STRUCT__entry(
+		    __field(    void *,		clnt			     )
+		    __field(	__u8,		type			     )
+		    __field(	__u32,		tag			     )
+		    ),
+
+	    TP_fast_assign(
+		    __entry->clnt    =  clnt;
+		    __entry->type    =  type;
+		    __entry->tag     =  tag;
+		    ),
+
+	    TP_printk("client %lu request %s tag  %d",
+		    (long)__entry->clnt, show_9p_op(__entry->type),
+		    __entry->tag)
+ );
+
+TRACE_EVENT(9p_client_res,
+	    TP_PROTO(struct p9_client *clnt, int8_t type, int tag, int err),
+
+	    TP_ARGS(clnt, type, tag, err),
+
+	    TP_STRUCT__entry(
+		    __field(    void *,		clnt			     )
+		    __field(	__u8,		type			     )
+		    __field(	__u32,		tag			     )
+		    __field(	__u32,		err			     )
+		    ),
+
+	    TP_fast_assign(
+		    __entry->clnt    =  clnt;
+		    __entry->type    =  type;
+		    __entry->tag     =  tag;
+		    __entry->err     =  err;
+		    ),
+
+	    TP_printk("client %lu response %s tag  %d err %d",
+		      (long)__entry->clnt, show_9p_op(__entry->type),
+		      __entry->tag, __entry->err)
+);
+
+/* dump 32 bytes of protocol data */
+#define P9_PROTO_DUMP_SZ 32
+TRACE_EVENT(9p_protocol_dump,
+	    TP_PROTO(struct p9_client *clnt, struct p9_fcall *pdu),
+
+	    TP_ARGS(clnt, pdu),
+
+	    TP_STRUCT__entry(
+		    __field(	void *,		clnt				)
+		    __field(	__u8,		type				)
+		    __field(	__u16,		tag				)
+		    __dynamic_array(unsigned char, line,
+				min_t(size_t, pdu->capacity, P9_PROTO_DUMP_SZ))
+		    ),
+
+	    TP_fast_assign(
+		    __entry->clnt   =  clnt;
+		    __entry->type   =  pdu->id;
+		    __entry->tag    =  pdu->tag;
+		    memcpy(__get_dynamic_array(line), pdu->sdata,
+				__get_dynamic_array_len(line));
+		    ),
+	    TP_printk("clnt %lu %s(tag = %d)\n%*ph\n",
+		      (unsigned long)__entry->clnt, show_9p_op(__entry->type),
+		      __entry->tag, __get_dynamic_array_len(line),
+		      __get_dynamic_array(line))
+ );
+
+
+TRACE_EVENT(9p_fid_ref,
+	    TP_PROTO(struct p9_fid *fid, __u8 type),
+
+	    TP_ARGS(fid, type),
+
+	    TP_STRUCT__entry(
+		    __field(	int,	fid		)
+		    __field(	int,	refcount	)
+		    __field(	__u8, type	)
+		    ),
+
+	    TP_fast_assign(
+		    __entry->fid = fid->fid;
+		    __entry->refcount = refcount_read(&fid->count);
+		    __entry->type = type;
+		    ),
+
+	    TP_printk("%s fid %d, refcount %d",
+		      show_9p_fid_reftype(__entry->type),
+		      __entry->fid, __entry->refcount)
+);
+
+
+#endif /* _TRACE_9P_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>