target-i386: Topology & APIC ID utility functions

This introduces utility functions for the APIC ID calculation, based on:
  Intel® 64 Architecture Processor Topology Enumeration
  http://software.intel.com/en-us/articles/intel-64-architecture-processor-topology-enumeration/

The code should be compatible with AMD's "Extended Method" described at:
  AMD CPUID Specification (Publication #25481)
  Section 3: Multiple Core Calcuation
as long as:
 - nr_threads is set to 1;
 - OFFSET_IDX is assumed to be 0;
 - CPUID Fn8000_0008_ECX[ApicIdCoreIdSize[3:0]] is set to
   apicid_core_width().

Unit tests included.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>

1 files changed, 136 insertions, 0 deletions

diff --git a/target-i386/topology.h b/target-i386/topology.h
new file mode 100644
index 0000000000..24ed525453
--- /dev/null
+++ b/target-i386/topology.h
@@ -0,0 +1,136 @@
+/*
+ *  x86 CPU topology data structures and functions
+ *
+ *  Copyright (c) 2012 Red Hat Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef TARGET_I386_TOPOLOGY_H
+#define TARGET_I386_TOPOLOGY_H
+
+/* This file implements the APIC-ID-based CPU topology enumeration logic,
+ * documented at the following document:
+ *   Intel® 64 Architecture Processor Topology Enumeration
+ *   http://software.intel.com/en-us/articles/intel-64-architecture-processor-topology-enumeration/
+ *
+ * This code should be compatible with AMD's "Extended Method" described at:
+ *   AMD CPUID Specification (Publication #25481)
+ *   Section 3: Multiple Core Calcuation
+ * as long as:
+ *  nr_threads is set to 1;
+ *  OFFSET_IDX is assumed to be 0;
+ *  CPUID Fn8000_0008_ECX[ApicIdCoreIdSize[3:0]] is set to apicid_core_width().
+ */
+
+#include <stdint.h>
+#include <string.h>
+
+#include "qemu/bitops.h"
+
+/* APIC IDs can be 32-bit, but beware: APIC IDs > 255 require x2APIC support
+ */
+typedef uint32_t apic_id_t;
+
+/* Return the bit width needed for 'count' IDs
+ */
+static unsigned apicid_bitwidth_for_count(unsigned count)
+{
+    g_assert(count >= 1);
+    if (count == 1) {
+        return 0;
+    }
+    return bitops_flsl(count - 1) + 1;
+}
+
+/* Bit width of the SMT_ID (thread ID) field on the APIC ID
+ */
+static inline unsigned apicid_smt_width(unsigned nr_cores, unsigned nr_threads)
+{
+    return apicid_bitwidth_for_count(nr_threads);
+}
+
+/* Bit width of the Core_ID field
+ */
+static inline unsigned apicid_core_width(unsigned nr_cores, unsigned nr_threads)
+{
+    return apicid_bitwidth_for_count(nr_cores);
+}
+
+/* Bit offset of the Core_ID field
+ */
+static inline unsigned apicid_core_offset(unsigned nr_cores,
+                                          unsigned nr_threads)
+{
+    return apicid_smt_width(nr_cores, nr_threads);
+}
+
+/* Bit offset of the Pkg_ID (socket ID) field
+ */
+static inline unsigned apicid_pkg_offset(unsigned nr_cores, unsigned nr_threads)
+{
+    return apicid_core_offset(nr_cores, nr_threads) +
+           apicid_core_width(nr_cores, nr_threads);
+}
+
+/* Make APIC ID for the CPU based on Pkg_ID, Core_ID, SMT_ID
+ *
+ * The caller must make sure core_id < nr_cores and smt_id < nr_threads.
+ */
+static inline apic_id_t apicid_from_topo_ids(unsigned nr_cores,
+                                             unsigned nr_threads,
+                                             unsigned pkg_id,
+                                             unsigned core_id,
+                                             unsigned smt_id)
+{
+    return (pkg_id  << apicid_pkg_offset(nr_cores, nr_threads)) |
+           (core_id << apicid_core_offset(nr_cores, nr_threads)) |
+           smt_id;
+}
+
+/* Calculate thread/core/package IDs for a specific topology,
+ * based on (contiguous) CPU index
+ */
+static inline void x86_topo_ids_from_idx(unsigned nr_cores,
+                                         unsigned nr_threads,
+                                         unsigned cpu_index,
+                                         unsigned *pkg_id,
+                                         unsigned *core_id,
+                                         unsigned *smt_id)
+{
+    unsigned core_index = cpu_index / nr_threads;
+    *smt_id = cpu_index % nr_threads;
+    *core_id = core_index % nr_cores;
+    *pkg_id = core_index / nr_cores;
+}
+
+/* Make APIC ID for the CPU 'cpu_index'
+ *
+ * 'cpu_index' is a sequential, contiguous ID for the CPU.
+ */
+static inline apic_id_t x86_apicid_from_cpu_idx(unsigned nr_cores,
+                                                unsigned nr_threads,
+                                                unsigned cpu_index)
+{
+    unsigned pkg_id, core_id, smt_id;
+    x86_topo_ids_from_idx(nr_cores, nr_threads, cpu_index,
+                          &pkg_id, &core_id, &smt_id);
+    return apicid_from_topo_ids(nr_cores, nr_threads, pkg_id, core_id, smt_id);
+}
+
+#endif /* TARGET_I386_TOPOLOGY_H */