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Diffstat (limited to 'arch/x86/kernel/cpu/perf_event.c')
-rw-r--r--arch/x86/kernel/cpu/perf_event.c16
1 files changed, 12 insertions, 4 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 915b876edd1e..4a3374e61a93 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -208,12 +208,14 @@ static bool check_hw_exists(void)
}
/*
- * Now write a value and read it back to see if it matches,
- * this is needed to detect certain hardware emulators (qemu/kvm)
- * that don't trap on the MSR access and always return 0s.
+ * Read the current value, change it and read it back to see if it
+ * matches, this is needed to detect certain hardware emulators
+ * (qemu/kvm) that don't trap on the MSR access and always return 0s.
*/
- val = 0xabcdUL;
reg = x86_pmu_event_addr(0);
+ if (rdmsrl_safe(reg, &val))
+ goto msr_fail;
+ val ^= 0xffffUL;
ret = wrmsrl_safe(reg, val);
ret |= rdmsrl_safe(reg, &val_new);
if (ret || val != val_new)
@@ -338,6 +340,9 @@ int x86_setup_perfctr(struct perf_event *event)
/* BTS is currently only allowed for user-mode. */
if (!attr->exclude_kernel)
return -EOPNOTSUPP;
+
+ if (!attr->exclude_guest)
+ return -EOPNOTSUPP;
}
hwc->config |= config;
@@ -380,6 +385,9 @@ int x86_pmu_hw_config(struct perf_event *event)
if (event->attr.precise_ip) {
int precise = 0;
+ if (!event->attr.exclude_guest)
+ return -EOPNOTSUPP;
+
/* Support for constant skid */
if (x86_pmu.pebs_active && !x86_pmu.pebs_broken) {
precise++;