perfcounters: IRQ and NMI support on AMD CPUs, fix

The BKGD suggests that counter width on AMD CPUs is 48 for all
existing models (it certainly is for mine).

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 14 deletions

diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index 6ebe9abf6aef..f5853718d4d3 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -959,20 +959,8 @@ static struct pmc_x86_ops *pmc_amd_init(void)
 
         nr_counters_generic = 4;
         nr_counters_fixed = 0;
-        counter_value_mask = ~0ULL;
-
-        rdmsrl(MSR_K7_PERFCTR0, old);
-        wrmsrl(MSR_K7_PERFCTR0, counter_value_mask);
-        /*
-         * read the truncated mask
-         */
-        rdmsrl(MSR_K7_PERFCTR0, counter_value_mask);
-        wrmsrl(MSR_K7_PERFCTR0, old);
-
-        bits = 32 + fls(counter_value_mask >> 32);
-        if (bits == 32)
-                bits = fls((u32)counter_value_mask);
-        counter_value_bits = bits;
+        counter_value_mask = 0x0000FFFFFFFFFFFFULL;
+        counter_value_bits = 48;
 
         pr_info("AMD Performance Monitoring support detected.\n");