[Qemu-devel] [PATCH 1/2] target-i386: move cpu halted decision into x86_cpu_reset

[Igor Mammedov]

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

Signed-off-by: Igor Mammedov <address@hidden>

---
Changelog:
 v2:
   - fix build for i386-linux-user
      spotted-by: Peter Maydell <address@hidden>
 v3:
   - style change requested by Andreas Färber <address@hidden>

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

 v5:
   - move Changelog under ---
      requested by: Peter Maydell <address@hidden>

 1) [PATCH qom-next 06/59] pc: Pass X86CPU to cpu_is_bsp()
   SoB: Andreas Färber <address@hidden>
   http://lists.gnu.org/archive/html/qemu-devel/2012-05/msg03185.html

 hw/apic.h            |    5 ++++-
 hw/apic_common.c     |   16 +++++++++++++---
 hw/pc.c              |    9 ---------
 target-i386/cpu.c    |   16 ++++++++++++++++
 target-i386/helper.c |    1 -
 target-i386/kvm.c    |    4 +++-
 6 files changed, 36 insertions(+), 15 deletions(-)

diff --git a/hw/apic.h b/hw/apic.h
index a89542b..1d48e02 100644
--- a/hw/apic.h
+++ b/hw/apic.h
@@ -21,9 +21,12 @@ void apic_sipi(DeviceState *s);
 void apic_handle_tpr_access_report(DeviceState *d, target_ulong ip,
                                    TPRAccess access);
 void apic_poll_irq(DeviceState *d);
+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 598267a..a920686 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -857,12 +857,6 @@ 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) {
@@ -913,10 +907,7 @@ 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 b3bcbac..cf612a8 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -1686,8 +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)
 {
     CPUX86State *cenv = &cpu->env;
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 e53c2f6..4cfb3fa 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -584,11 +584,13 @@ 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