[Qemu-devel] [PATCH v2] MP initialization protocol differs between cpu families, and for P6 and onward models it is up to CPU to decide if it will be BSP using this protocol, so try to model this. However there is no point in implementing MP initialization protocol in qemu. Thus first CPU is always marked as BSP.

[Igor Mammedov <imammedo@redhat.com>]

This patch:
 - moves decision to designate BSP from board into cpu, making cpu
self-sufficient in this regard. Later it will allow to cleanup hw/pc.c
and remove cpu_reset and wrappers from there.
 - stores flag that CPU is BSP in IA32_APIC_BASE to model behavior
described in Inted SDM vol 3a part 1 chapter 8.4.1
 - uses MSR_IA32_APICBASE_BSP flag in apic_base for checking if cpu is BSP

patch is based on Jan Kiszka's proposal:
    http://thread.gmane.org/gmane.comp.emulators.qemu/100806

v2:
  - fix build for i386-linux-user
      spotted-by: Peter Maydell <peter.maydell@linaro.org>
v3:
  - style change requested by Andreas Färber <afaerber@suse.de>

v4:
  - reuse cpu_is_bsp() rather than open code check if apicbase has BSP bit set
      requested by  Gleb Natapov <gleb@redhat.com>
  - hijacked Andreas' patch [1] to use X86CPU instead of CPUX86State in
    cpu_is_bsp()

  1)  http://lists.gnu.org/archive/html/qemu-devel/2012-05/msg03185.html

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
 hw/apic.h            |    5 ++++-
 hw/apic_common.c     |   16 +++++++++++++---
 hw/pc.c              |    9 ---------
 target-i386/cpu.c    |   18 ++++++++++++++++++
 target-i386/helper.c |    1 -
 target-i386/kvm.c    |    4 +++-
 6 files changed, 38 insertions(+), 15 deletions(-)

diff --git a/hw/apic.h b/hw/apic.h
index 62179ce..4da10b6 100644
--- a/hw/apic.h
+++ b/hw/apic.h
@@ -20,9 +20,12 @@ void apic_init_reset(DeviceState *s);
 void apic_sipi(DeviceState *s);
 void apic_handle_tpr_access_report(DeviceState *d, target_ulong ip,
                                    TPRAccess access);
+void apic_designate_bsp(DeviceState *d);
 
 /* pc.c */
-int cpu_is_bsp(CPUX86State *env);
 DeviceState *cpu_get_current_apic(void);
 
+/* cpu.c */
+bool cpu_is_bsp(X86CPU *cpu);
+
 #endif
diff --git a/hw/apic_common.c b/hw/apic_common.c
index 60b8259..58e63b0 100644
--- a/hw/apic_common.c
+++ b/hw/apic_common.c
@@ -43,8 +43,8 @@ uint64_t cpu_get_apic_base(DeviceState *d)
         trace_cpu_get_apic_base((uint64_t)s->apicbase);
         return s->apicbase;
     } else {
-        trace_cpu_get_apic_base(0);
-        return 0;
+        trace_cpu_get_apic_base(MSR_IA32_APICBASE_BSP);
+        return MSR_IA32_APICBASE_BSP;
     }
 }
 
@@ -201,13 +201,23 @@ void apic_init_reset(DeviceState *d)
     s->timer_expiry = -1;
 }
 
+void apic_designate_bsp(DeviceState *d)
+{
+    if (d == NULL) {
+        return;
+    }
+
+    APICCommonState *s = APIC_COMMON(d);
+    s->apicbase |= MSR_IA32_APICBASE_BSP;
+}
+
 static void apic_reset_common(DeviceState *d)
 {
     APICCommonState *s = DO_UPCAST(APICCommonState, busdev.qdev, d);
     APICCommonClass *info = APIC_COMMON_GET_CLASS(s);
     bool bsp;
 
-    bsp = cpu_is_bsp(s->cpu_env);
+    bsp = cpu_is_bsp(x86_env_get_cpu(s->cpu_env));
     s->apicbase = 0xfee00000 |
         (bsp ? MSR_IA32_APICBASE_BSP : 0) | MSR_IA32_APICBASE_ENABLE;
 
diff --git a/hw/pc.c b/hw/pc.c
index c7e9ab3..50c1715 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -871,12 +871,6 @@ void pc_init_ne2k_isa(ISABus *bus, NICInfo *nd)
     nb_ne2k++;
 }
 
-int cpu_is_bsp(CPUX86State *env)
-{
-    /* We hard-wire the BSP to the first CPU. */
-    return env->cpu_index == 0;
-}
-
 DeviceState *cpu_get_current_apic(void)
 {
     if (cpu_single_env) {
@@ -927,10 +921,7 @@ void pc_acpi_smi_interrupt(void *opaque, int irq, int level)
 static void pc_cpu_reset(void *opaque)
 {
     X86CPU *cpu = opaque;
-    CPUX86State *env = &cpu->env;
-
     cpu_reset(CPU(cpu));
-    env->halted = !cpu_is_bsp(env);
 }
 
 static X86CPU *pc_new_cpu(const char *cpu_model)
diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 5521709..0c38b7f 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -1686,6 +1686,24 @@ static void x86_cpu_reset(CPUState *s)
     env->dr[7] = DR7_FIXED_1;
     cpu_breakpoint_remove_all(env, BP_CPU);
     cpu_watchpoint_remove_all(env, BP_CPU);
+
+#if !defined(CONFIG_USER_ONLY)
+    /* We hard-wire the BSP to the first CPU. */
+    if (env->cpu_index == 0) {
+        apic_designate_bsp(env->apic_state);
+    }
+
+    env->halted = !cpu_is_bsp(cpu);
+#endif
+}
+
+#ifndef CONFIG_USER_ONLY
+bool cpu_is_bsp(X86CPU *cpu)
+{
+    return cpu_get_apic_base(cpu->env.apic_state) & MSR_IA32_APICBASE_BSP;
+}
+#endif
+
 }
 
 static void mce_init(X86CPU *cpu)
diff --git a/target-i386/helper.c b/target-i386/helper.c
index d3af6ea..b748d90 100644
--- a/target-i386/helper.c
+++ b/target-i386/helper.c
@@ -1191,7 +1191,6 @@ void do_cpu_init(X86CPU *cpu)
     env->interrupt_request = sipi;
     env->pat = pat;
     apic_init_reset(env->apic_state);
-    env->halted = !cpu_is_bsp(env);
 }
 
 void do_cpu_sipi(X86CPU *cpu)
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 0d0d8f6..97a2cb1 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -579,11 +579,13 @@ int kvm_arch_init_vcpu(CPUX86State *env)
 
 void kvm_arch_reset_vcpu(CPUX86State *env)
 {
+    X86CPU *cpu = x86_env_get_cpu(env);
+
     env->exception_injected = -1;
     env->interrupt_injected = -1;
     env->xcr0 = 1;
     if (kvm_irqchip_in_kernel()) {
-        env->mp_state = cpu_is_bsp(env) ? KVM_MP_STATE_RUNNABLE :
+        env->mp_state = cpu_is_bsp(cpu) ? KVM_MP_STATE_RUNNABLE :
                                           KVM_MP_STATE_UNINITIALIZED;
     } else {
         env->mp_state = KVM_MP_STATE_RUNNABLE;
-- 
1.7.1