sparc: Don't do expensive hypervisor PCR write unless necessary.

The hypervisor call is only necessary if hypervisor events are
being requested.

So if we're not tracking hypervisor events, simply do a direct
register write.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 2 deletions

diff --git a/arch/sparc/kernel/pcr.c b/arch/sparc/kernel/pcr.c
index 8ac23e660080..878c6824c732 100644
--- a/arch/sparc/kernel/pcr.c
+++ b/arch/sparc/kernel/pcr.c
@@ -80,8 +80,11 @@ static void n2_pcr_write(u64 val)
 {
         unsigned long ret;
 
-        ret = sun4v_niagara2_setperf(HV_N2_PERF_SPARC_CTL, val);
-        if (ret != HV_EOK)
+        if (val & PCR_N2_HTRACE) {
+                ret = sun4v_niagara2_setperf(HV_N2_PERF_SPARC_CTL, val);
+                if (ret != HV_EOK)
+                        write_pcr(val);
+        } else
                 write_pcr(val);
 }