Commit 73fdeb66 authored Aug 31, 2015 by Huaitong Han Committed by Ingo Molnar Sep 13, 2015

perf/x86/intel/pt: Fix KVM warning due to doing rdmsr() before the CPUID test



If KVM does not support INTEL_PT, guest MSR_IA32_RTIT_CTL reading will
produce host warning like "kvm [2469]: vcpu0 unhandled rdmsr: 0x570".

Guest can determine whether the CPU supports Intel_PT according to CPUID,
so test_cpu_cap function is added before rdmsr,and it is more in line with
the code style.

Signed-off-by: Huaitong Han <huaitong.han@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: acme@kernel.org
Link: http://lkml.kernel.org/r/1441009262-9792-1-git-send-email-huaitong.han@intel.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 516792e6

arch/x86/kernel/cpu/perf_event_intel_pt.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -139,9 +139,6 @@ static int __init pt_pmu_hw_init(void)
		long i;

		attrs = NULL;
		ret = -ENODEV;
		if (!test_cpu_cap(&boot_cpu_data, X86_FEATURE_INTEL_PT))
		goto fail;

		for (i = 0; i < PT_CPUID_LEAVES; i++) {
		cpuid_count(20, i,
		@@ -1130,6 +1127,10 @@ static __init int pt_init(void)
		int ret, cpu, prior_warn = 0;

		BUILD_BUG_ON(sizeof(struct topa) > PAGE_SIZE);

		if (!test_cpu_cap(&boot_cpu_data, X86_FEATURE_INTEL_PT))
		return -ENODEV;

		get_online_cpus();
		for_each_online_cpu(cpu) {
		u64 ctl;