[Qemu-devel] [PATCH 4/5] target-i386: move cpu halted decision into x86_cpu_reset

[Igor Mammedov <imammedo@redhat.com>]

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.

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
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
 hw/apic.h            |    2 +-
 hw/apic_common.c     |   20 ++++++++++++++------
 hw/pc.c              |    9 ---------
 target-i386/cpu.c    |    9 +++++++++
 target-i386/helper.c |    1 -
 target-i386/kvm.c    |    5 +++--
 6 files changed, 27 insertions(+), 19 deletions(-)

diff --git a/hw/apic.h b/hw/apic.h
index 62179ce..d961ed4 100644
--- a/hw/apic.h
+++ b/hw/apic.h
@@ -20,9 +20,9 @@ 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);
 
 #endif
diff --git a/hw/apic_common.c b/hw/apic_common.c
index 60b8259..095b09e 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;
     }
 }
 
@@ -201,22 +201,30 @@ 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);
     s->apicbase = 0xfee00000 |
-        (bsp ? MSR_IA32_APICBASE_BSP : 0) | MSR_IA32_APICBASE_ENABLE;
+        (s->apicbase & MSR_IA32_APICBASE_BSP) | MSR_IA32_APICBASE_ENABLE;
 
     s->vapic_paddr = 0;
     info->vapic_base_update(s);
 
     apic_init_reset(d);
 
-    if (bsp) {
+    if (s->apicbase & MSR_IA32_APICBASE_BSP) {
         /*
          * LINT0 delivery mode on CPU #0 is set to ExtInt at initialization
          * time typically by BIOS, so PIC interrupt can be delivered to the
diff --git a/hw/pc.c b/hw/pc.c
index 8a662cf..2af066a 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 7ace126..d400f4b 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -1678,6 +1678,15 @@ 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_get_apic_base(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 b38ea7f..a8e403d 100644
--- a/target-i386/helper.c
+++ b/target-i386/helper.c
@@ -1175,7 +1175,6 @@ 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..09621e5 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -583,8 +583,9 @@ void kvm_arch_reset_vcpu(CPUX86State *env)
     env->interrupt_injected = -1;
     env->xcr0 = 1;
     if (kvm_irqchip_in_kernel()) {
-        env->mp_state = cpu_is_bsp(env) ? KVM_MP_STATE_RUNNABLE :
-                                          KVM_MP_STATE_UNINITIALIZED;
+        env->mp_state =
+            cpu_get_apic_base(env->apic_state) & MSR_IA32_APICBASE_BSP ?
+            KVM_MP_STATE_RUNNABLE : KVM_MP_STATE_UNINITIALIZED;
     } else {
         env->mp_state = KVM_MP_STATE_RUNNABLE;
     }
-- 
1.7.10.2