KVM: kvmtrace: replace get_cycles with ktime_get v3

The current kvmtrace code uses get_cycles() while the interpretation would be
easier using using nanoseconds. ktime_get() should give at least the same
accuracy as get_cycles on all architectures (even better on 32bit archs) but
at a better unit (e.g. comparable between hosts with different frequencies.

[avi: avoid ktime_t in public header]

Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 8a16b08..5d08f11 100644 (file)
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -322,12 +322,12 @@ struct kvm_trace_rec {
        __u32 vcpu_id;
        union {
                struct {
-                       __u64 cycle_u64;
+                       __u64 timestamp;
                        __u32 extra_u32[KVM_TRC_EXTRA_MAX];
-               } __attribute__((packed)) cycle;
+               } __attribute__((packed)) timestamp;
                struct {
                        __u32 extra_u32[KVM_TRC_EXTRA_MAX];
-               } nocycle;
+               } notimestamp;
        } u;
 };
 

diff --git a/virt/kvm/kvm_trace.c b/virt/kvm/kvm_trace.c
index 9acb78b..41dcc84 100644 (file)
--- a/virt/kvm/kvm_trace.c
+++ b/virt/kvm/kvm_trace.c
@@ -17,6 +17,7 @@
 #include <linux/module.h>
 #include <linux/relay.h>
 #include <linux/debugfs.h>
+#include <linux/ktime.h>
 
 #include <linux/kvm_host.h>
 
@@ -35,16 +36,16 @@ static struct kvm_trace *kvm_trace;
 struct kvm_trace_probe {
        const char *name;
        const char *format;
-       u32 cycle_in;
+       u32 timestamp_in;
        marker_probe_func *probe_func;
 };
 
-static inline int calc_rec_size(int cycle, int extra)
+static inline int calc_rec_size(int timestamp, int extra)
 {
        int rec_size = KVM_TRC_HEAD_SIZE;
 
        rec_size += extra;
-       return cycle ? rec_size += KVM_TRC_CYCLE_SIZE : rec_size;
+       return timestamp ? rec_size += KVM_TRC_CYCLE_SIZE : rec_size;
 }
 
 static void kvm_add_trace(void *probe_private, void *call_data,
@@ -69,20 +70,20 @@ static void kvm_add_trace(void *probe_private, void *call_data,
        WARN_ON(!(extra <= KVM_TRC_EXTRA_MAX));
        extra           = min_t(u32, extra, KVM_TRC_EXTRA_MAX);
 
-       rec.rec_val |= TRACE_REC_TCS(p->cycle_in)
+       rec.rec_val |= TRACE_REC_TCS(p->timestamp_in)
                        | TRACE_REC_NUM_DATA_ARGS(extra);
 
-       if (p->cycle_in) {
-               rec.u.cycle.cycle_u64 = get_cycles();
+       if (p->timestamp_in) {
+               rec.u.timestamp.timestamp = ktime_to_ns(ktime_get());
 
                for (i = 0; i < extra; i++)
-                       rec.u.cycle.extra_u32[i] = va_arg(*args, u32);
+                       rec.u.timestamp.extra_u32[i] = va_arg(*args, u32);
        } else {
                for (i = 0; i < extra; i++)
-                       rec.u.nocycle.extra_u32[i] = va_arg(*args, u32);
+                       rec.u.notimestamp.extra_u32[i] = va_arg(*args, u32);
        }
 
-       size = calc_rec_size(p->cycle_in, extra * sizeof(u32));
+       size = calc_rec_size(p->timestamp_in, extra * sizeof(u32));
        relay_write(kt->rchan, &rec, size);
 }