MFC r316017,r316020: add SMT detection for newer AMD processors

1 files changed, 19 insertions, 4 deletions

diff --git a/sys/x86/x86/mp_x86.c b/sys/x86/x86/mp_x86.c
index 9de5339..cd66eea 100644
--- a/sys/x86/x86/mp_x86.c
+++ b/sys/x86/x86/mp_x86.c
@@ -226,11 +226,10 @@ add_deterministic_cache(int type, int level, int share_count)
  * Determine topology of processing units and caches for AMD CPUs.
  * See:
  *  - AMD CPUID Specification (Publication # 25481)
- *  - BKDG For AMD Family 10h Processors (Publication # 31116), section 2.15
  *  - BKDG for AMD NPT Family 0Fh Processors (Publication # 32559)
- * XXX At the moment the code does not recognize grouping of AMD CMT threads,
- * if supported, into cores, so each thread is treated as being in its own
- * core.  In other words, each logical CPU is considered to be a core.
+ *  - BKDG For AMD Family 10h Processors (Publication # 31116)
+ *  - BKDG For AMD Family 15h Models 00h-0Fh Processors (Publication # 42301)
+ *  - BKDG For AMD Family 16h Models 00h-0Fh Processors (Publication # 48751)
  */
 static void
 topo_probe_amd(void)
@@ -254,6 +253,22 @@ topo_probe_amd(void)
 		pkg_id_shift =
 		    mask_width((cpu_procinfo2 & AMDID_CMP_CORES) + 1);
 
+	/*
+	 * Families prior to 16h define the following value as
+	 * cores per compute unit and we don't really care about the AMD
+	 * compute units at the moment.  Perhaps we should treat them as
+	 * cores and cores within the compute units as hardware threads,
+	 * but that's up for debate.
+	 * Later families define the value as threads per compute unit,
+	 * so we are following AMD's nomenclature here.
+	 */
+	if ((amd_feature2 & AMDID2_TOPOLOGY) != 0 &&
+	    CPUID_TO_FAMILY(cpu_id) >= 0x16) {
+		cpuid_count(0x8000001e, 0, p);
+		share_count = ((p[1] >> 8) & 0xff) + 1;
+		core_id_shift = mask_width(share_count);
+	}
+
 	if ((amd_feature2 & AMDID2_TOPOLOGY) != 0) {
 		for (i = 0; ; i++) {
 			cpuid_count(0x8000001d, i, p);