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>

diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index 6ebe9ab..f585371 100644 (file)
--- 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");