[Qemu-devel] [PATCH 27/27] pc: generate APIC IDs according to CPU topology

[Eduardo Habkost]

This keeps compatibility on machine-types pc-1.2 and older, and prints a
warning in case the requested configuration won't get the correct
topology.

Signed-off-by: Eduardo Habkost <address@hidden>
---
Changes v1 -> v2:
 - Move code to cpu.c
 - keep using cpu_index on *-user
 - Use SMP.contiguous_apic_ids global property
 - Prints warning in case the compatibility mode will expose incorrect
   topology

Changes v2 -> v3:
 - Now all code is inside hw/pc.c
 - Use a real "PC" class and a "contiguous_apic_ids" property

Changes v3 -> v4:
 - Instead of using a global property, use a separate machine init
   function and a PCInitArgs field, to implement compatibility mode
 - Use error_report() instead of fprintf(stderr) for the warning
 - Use a field on PCInitArgs instead of a static variable to check
   if warning was already printed
---
 hw/pc.c      | 19 +++++++++++++++----
 hw/pc.h      |  6 ++++++
 hw/pc_piix.c |  1 +
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/hw/pc.c b/hw/pc.c
index 8895087..3d08271 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -51,6 +51,8 @@
 #include "exec-memory.h"
 #include "arch_init.h"
 #include "bitmap.h"
+#include "topology.h"
+#include "cpus.h"
 
 /* debug PC/ISA interrupts */
 //#define DEBUG_IRQ
@@ -562,10 +564,19 @@ static void bochs_bios_write(void *opaque, uint32_t addr, 
uint32_t val)
  */
 static uint32_t apic_id_for_cpu(PCInitArgs *args, int cpu_index)
 {
-    /* right now APIC ID == CPU index. this will eventually change to use
-     * the CPU topology configuration properly
-     */
-    return cpu_index;
+    uint32_t correct_id;
+
+    correct_id = topo_apicid_for_cpu(smp_cores, smp_threads, cpu_index);
+    if (args->compat_contiguous_apic_ids) {
+        if (cpu_index != correct_id && !args->apic_id_warned) {
+            error_report("APIC IDs set in compatibility mode, "
+                         "CPU topology won't match the configuration");
+            args->apic_id_warned = true;
+        }
+        return cpu_index;
+    } else {
+        return correct_id;
+    }
 }
 
 int e820_add_entry(uint64_t address, uint64_t length, uint32_t type)
diff --git a/hw/pc.h b/hw/pc.h
index 53883f5..a14944a 100644
--- a/hw/pc.h
+++ b/hw/pc.h
@@ -81,6 +81,12 @@ typedef struct PCInitArgs {
     QEMUMachineInitArgs *qemu_args;
     bool pci_enabled;
     bool kvmclock_enabled;
+    /* Enable compatibility (buggy) APIC ID generation, that keep APIC IDs
+     * contiguous
+     */
+    bool compat_contiguous_apic_ids;
+    /* Warning message about incorrect APIC ID was shown */
+    bool apic_id_warned;
 
     /* Memory regions & sizes: */
     MemoryRegion *system_memory;
diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index 57a3228..79a54e6 100644
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -298,6 +298,7 @@ static void pc_init_pci_v1_2(QEMUMachineInitArgs *args)
         .qemu_args = args,
         .pci_enabled = true,
         .kvmclock_enabled = true,
+        .compat_contiguous_apic_ids = true,
     };
     pc_init1(&pc_args);
 }
-- 
1.7.11.7