diff mbox

[1/1] KVM: x86: improve the usability of the 'kvm_pio' tracepoint

Message ID 1399046267-4677-2-git-send-email-uobergfe@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Ulrich Obergfell May 2, 2014, 3:57 p.m. UTC 
This patch moves the 'kvm_pio' tracepoint to emulator_pio_in_emulated()
and emulator_pio_out_emulated(), and it adds an argument (a pointer to
the 'pio_data'). A single 8-bit or 16-bit or 32-bit data item is fetched
from 'pio_data' (depending on 'size'), and the value is included in the
trace record ('val'). If 'count' is greater than one, this is indicated
by the string "(...)" in the trace output.

Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com>
---
 arch/x86/kvm/trace.h | 20 ++++++++++++++++----
 arch/x86/kvm/x86.c   |  4 ++--
 2 files changed, 18 insertions(+), 6 deletions(-)

Comments

Paolo Bonzini May 5, 2014, 8:41 p.m. UTC | #1 
Il 02/05/2014 17:57, Ulrich Obergfell ha scritto:
> This patch moves the 'kvm_pio' tracepoint to emulator_pio_in_emulated()
> and emulator_pio_out_emulated(), and it adds an argument (a pointer to
> the 'pio_data'). A single 8-bit or 16-bit or 32-bit data item is fetched
> from 'pio_data' (depending on 'size'), and the value is included in the
> trace record ('val'). If 'count' is greater than one, this is indicated
> by the string "(...)" in the trace output.

A difference is that the tracepoint will be reported after an exit to 
userspace in the case of "in", rather than before.

The improvement however is noticeable; especially for "out" it allows to 
obtain much more information about the state of a device from a long 
trace.  Applying to kvm/queue, thanks.

Paolo
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diff mbox

Patch

diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index 545245d..33574c9 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -91,16 +91,21 @@  TRACE_EVENT(kvm_hv_hypercall,
 /*
  * Tracepoint for PIO.
  */
+
+#define KVM_PIO_IN   0
+#define KVM_PIO_OUT  1
+
 TRACE_EVENT(kvm_pio,
 	TP_PROTO(unsigned int rw, unsigned int port, unsigned int size,
-		 unsigned int count),
-	TP_ARGS(rw, port, size, count),
+		 unsigned int count, void *data),
+	TP_ARGS(rw, port, size, count, data),
 
 	TP_STRUCT__entry(
 		__field(	unsigned int, 	rw		)
 		__field(	unsigned int, 	port		)
 		__field(	unsigned int, 	size		)
 		__field(	unsigned int,	count		)
+		__field(	unsigned int,	val		)
 	),
 
 	TP_fast_assign(
@@ -108,11 +113,18 @@  TRACE_EVENT(kvm_pio,
 		__entry->port		= port;
 		__entry->size		= size;
 		__entry->count		= count;
+		if (size == 1)
+			__entry->val	= *(unsigned char *)data;
+		else if (size == 2)
+			__entry->val	= *(unsigned short *)data;
+		else
+			__entry->val	= *(unsigned int *)data;
 	),
 
-	TP_printk("pio_%s at 0x%x size %d count %d",
+	TP_printk("pio_%s at 0x%x size %d count %d val 0x%x %s",
 		  __entry->rw ? "write" : "read",
-		  __entry->port, __entry->size, __entry->count)
+		  __entry->port, __entry->size, __entry->count, __entry->val,
+		  __entry->count > 1 ? "(...)" : "")
 );
 
 /*
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8b8fc0b..cd79707 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4486,8 +4486,6 @@  static int emulator_pio_in_out(struct kvm_vcpu *vcpu, int size,
 			       unsigned short port, void *val,
 			       unsigned int count, bool in)
 {
-	trace_kvm_pio(!in, port, size, count);
-
 	vcpu->arch.pio.port = port;
 	vcpu->arch.pio.in = in;
 	vcpu->arch.pio.count  = count;
@@ -4522,6 +4520,7 @@  static int emulator_pio_in_emulated(struct x86_emulate_ctxt *ctxt,
 	if (ret) {
 data_avail:
 		memcpy(val, vcpu->arch.pio_data, size * count);
+		trace_kvm_pio(KVM_PIO_IN, port, size, count, vcpu->arch.pio_data);
 		vcpu->arch.pio.count = 0;
 		return 1;
 	}
@@ -4536,6 +4535,7 @@  static int emulator_pio_out_emulated(struct x86_emulate_ctxt *ctxt,
 	struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
 
 	memcpy(vcpu->arch.pio_data, val, size * count);
+	trace_kvm_pio(KVM_PIO_OUT, port, size, count, vcpu->arch.pio_data);
 	return emulator_pio_in_out(vcpu, size, port, (void *)val, count, false);
 }