[PATCH 3/3] KVM: Adding tracepoints for guest page hinting

[Nitesh Narayan Lal <nilal@redhat.com>]

Signed-off-by: Nitesh Narayan Lal <nilal@redhat.com>
---
 include/trace/events/kvm.h | 101 +++++++++++++++++++++++++++++++++++++++++++++
 virt/kvm/page_hinting.c    |  17 ++++++++
 2 files changed, 118 insertions(+)

diff --git a/include/trace/events/kvm.h b/include/trace/events/kvm.h
index 8ade3eb..96d29a4 100644
--- a/include/trace/events/kvm.h
+++ b/include/trace/events/kvm.h
@@ -393,6 +393,107 @@ TRACE_EVENT(kvm_halt_poll_ns,
 #define trace_kvm_halt_poll_ns_shrink(vcpu_id, new, old) \
 	trace_kvm_halt_poll_ns(false, vcpu_id, new, old)
 
+TRACE_EVENT(guest_free_page,
+	    TP_PROTO(struct page *page, unsigned int order),
+
+	TP_ARGS(page, order),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, pfn)
+		__field(unsigned int, order)
+	),
+
+	TP_fast_assign(
+		__entry->pfn            = page_to_pfn(page);
+		__entry->order          = order;
+	),
+
+	TP_printk("page=%p pfn=%lu number of pages=%d",
+		  pfn_to_page(__entry->pfn),
+		  __entry->pfn,
+		  (1 << __entry->order))
+);
+
+TRACE_EVENT(guest_alloc_page,
+	    TP_PROTO(struct page *page, unsigned int order),
+
+	TP_ARGS(page, order),
+
+	TP_STRUCT__entry(
+		__field(unsigned long,  pfn)
+		__field(unsigned int,   order)
+	),
+
+	TP_fast_assign(
+		__entry->pfn            = page_to_pfn(page);
+		__entry->order          = order;
+		),
+
+	TP_printk("page=%p pfn=%lu number of pages=%d",
+		  pfn_to_page(__entry->pfn),
+		  __entry->pfn,
+		  (1 << __entry->order))
+);
+
+TRACE_EVENT(guest_free_page_slowpath,
+	    TP_PROTO(unsigned long pfn, unsigned int pages),
+
+	TP_ARGS(pfn, pages),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, pfn)
+		__field(unsigned int, pages)
+	),
+
+	TP_fast_assign(
+		__entry->pfn            = pfn;
+		__entry->pages          = pages;
+	),
+
+	TP_printk("pfn=%lu number of pages=%u",
+		  __entry->pfn,
+		  __entry->pages)
+);
+
+TRACE_EVENT(guest_pfn_dump,
+	    TP_PROTO(char *type, unsigned long pfn, unsigned int pages),
+
+	TP_ARGS(type, pfn, pages),
+
+	TP_STRUCT__entry(
+		__field(char *, type)
+		__field(unsigned long, pfn)
+		__field(unsigned int, pages)
+	),
+
+	TP_fast_assign(
+		__entry->type		= type;
+		__entry->pfn            = pfn;
+		__entry->pages          = pages;
+		),
+
+	TP_printk("Type=%s pfn=%lu number of pages=%d",
+		  __entry->type,
+		  __entry->pfn,
+		  __entry->pages)
+);
+
+TRACE_EVENT(guest_str_dump,
+	    TP_PROTO(char *str),
+
+	TP_ARGS(str),
+
+	TP_STRUCT__entry(
+		__field(char *, str)
+	),
+
+	TP_fast_assign(
+		__entry->str		= str;
+		),
+
+	TP_printk("Debug=%s",
+		  __entry->str)
+);
 #endif /* _TRACE_KVM_MAIN_H */
 
 /* This part must be outside protection */
diff --git a/virt/kvm/page_hinting.c b/virt/kvm/page_hinting.c
index cfdc513..5fb390e0 100644
--- a/virt/kvm/page_hinting.c
+++ b/virt/kvm/page_hinting.c
@@ -55,6 +55,7 @@ static void make_hypercall(void)
 	 * Dummy function: Tobe filled later.
 	 */
 	empty_hyperlist();
+	trace_guest_str_dump("Hypercall to host...:");
 }
 
 static int sort_pfn(const void *a1, const void *b1)
@@ -77,6 +78,9 @@ static int pack_hyperlist(void)
 
 	while (i < MAX_FGPT_ENTRIES  - 1) {
 		if (hypervisor_pagelist[i].pfn != 0) {
+			trace_guest_pfn_dump("Packing Hyperlist",
+					     hypervisor_pagelist[i].pfn,
+					     hypervisor_pagelist[i].pages);
 			hypervisor_pagelist[j].pfn =
 					hypervisor_pagelist[i].pfn;
 			hypervisor_pagelist[j].pages =
@@ -164,6 +168,9 @@ void copy_hyperlist(int hyper_idx)
 
 	free_page_obj = &get_cpu_var(kvm_pt)[0];
 	while (i < hyper_idx) {
+		trace_guest_pfn_dump("HyperList entry copied",
+				     hypervisor_pagelist[i].pfn,
+				     hypervisor_pagelist[i].pages);
 		free_page_obj[*idx].pfn = hypervisor_pagelist[i].pfn;
 		free_page_obj[*idx].pages = hypervisor_pagelist[i].pages;
 		*idx += 1;
@@ -204,11 +211,14 @@ void arch_free_page_slowpath(void)
 
 				pfn = head_pfn + alloc_pages;
 				prev_free = false;
+				trace_guest_pfn_dump("Compound",
+						     head_pfn, alloc_pages);
 				continue;
 			}
 			if (page_ref_count(p)) {
 				pfn++;
 				prev_free = false;
+				trace_guest_pfn_dump("Single", pfn, 1);
 				continue;
 			}
 			/*
@@ -216,6 +226,11 @@ void arch_free_page_slowpath(void)
 			 * hypervisor_pagelist if required.
 			 */
 			if (!prev_free) {
+				if (hyper_idx != -1) {
+					trace_guest_free_page_slowpath(
+					hypervisor_pagelist[hyper_idx].pfn,
+					hypervisor_pagelist[hyper_idx].pages);
+				}
 				hyper_idx++;
 				if (hyper_idx == MAX_FGPT_ENTRIES - 1) {
 					hyper_idx =  compress_hyperlist();
@@ -262,6 +277,7 @@ void arch_alloc_page(struct page *page, int order)
 	do {
 		seq = read_seqbegin(&guest_page_lock);
 	} while (read_seqretry(&guest_page_lock, seq));
+	trace_guest_alloc_page(page, order);
 }
 
 void arch_free_page(struct page *page, int order)
@@ -277,6 +293,7 @@ void arch_free_page(struct page *page, int order)
 	 */
 	local_irq_save(flags);
 	free_page_obj = &get_cpu_var(kvm_pt)[0];
+	trace_guest_free_page(page, order);
 	free_page_obj[*free_page_idx].pfn = page_to_pfn(page);
 	free_page_obj[*free_page_idx].pages = 1 << order;
 	*free_page_idx += 1;
-- 
2.9.4