perf/x86/amd/uncore: Detect available DF counters

If AMD Performance Monitoring Version 2 (PerfMonV2) is
supported, use CPUID leaf 0x80000022 EBX to detect the
number of Data Fabric (DF) PMCs. This offers more
flexibility if the counts change in later processor
families.

Signed-off-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/bac7b2806561e03f2acc7fdc9db94f102df80e1d.1652954372.git.sandipan.das@amd.com

diff --git a/arch/x86/events/amd/uncore.c b/arch/x86/events/amd/uncore.c
index c3e218dccf6e1f294ea29a1e14dcd270ea0e50e6..233dd405dd069e7b95eae06d36eaae0540983c2d 100644 (file)
--- a/arch/x86/events/amd/uncore.c
+++ b/arch/x86/events/amd/uncore.c
@@ -30,6 +30,7 @@
 #undef pr_fmt
 #define pr_fmt(fmt)    "amd_uncore: " fmt
 
+static int pmu_version;
 static int num_counters_llc;
 static int num_counters_nb;
 static bool l3_mask;
@@ -629,6 +630,7 @@ static int __init amd_uncore_init(void)
 {
        struct attribute **df_attr = amd_uncore_df_format_attr;
        struct attribute **l3_attr = amd_uncore_l3_format_attr;
+       union cpuid_0x80000022_ebx ebx;
        int ret = -ENODEV;
 
        if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
@@ -638,6 +640,9 @@ static int __init amd_uncore_init(void)
        if (!boot_cpu_has(X86_FEATURE_TOPOEXT))
                return -ENODEV;
 
+       if (boot_cpu_has(X86_FEATURE_PERFMON_V2))
+               pmu_version = 2;
+
        num_counters_nb = NUM_COUNTERS_NB;
        num_counters_llc = NUM_COUNTERS_L2;
        if (boot_cpu_data.x86 >= 0x17) {
@@ -666,6 +671,11 @@ static int __init amd_uncore_init(void)
                if (ret)
                        goto fail_nb;
 
+               if (pmu_version >= 2) {
+                       ebx.full = cpuid_ebx(EXT_PERFMON_DEBUG_FEATURES);
+                       num_counters_nb = ebx.split.num_df_pmc;
+               }
+
                pr_info("%d %s %s counters detected\n", num_counters_nb,
                        boot_cpu_data.x86_vendor == X86_VENDOR_HYGON ?  "HYGON" : "",
                        amd_nb_pmu.name);

diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index 409725e86f42c4453306c6d446ff04207e1b594d..af157aa74f4ed35cd456e64d435be01454037f12 100644 (file)
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -194,6 +194,9 @@ union cpuid_0x80000022_ebx {
        struct {
                /* Number of Core Performance Counters */
                unsigned int    num_core_pmc:4;
+               unsigned int    reserved:6;
+               /* Number of Data Fabric Counters */
+               unsigned int    num_df_pmc:6;
        } split;
        unsigned int            full;
 };