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

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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>
This commit is contained in:
Huaitong Han 2015-08-31 16:21:02 +08:00 committed by Ingo Molnar
parent 516792e67c
commit 73fdeb6659
1 changed files with 4 additions and 3 deletions
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7
arch/x86/kernel/cpu/perf_event_intel_pt.c
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@ -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;