[Qemu-devel] [PATCH] x86/lapic: Load LAPIC state at post_load

[Dr. David Alan Gilbert (git)]

From: "Dr. David Alan Gilbert" <address@hidden>

Load the LAPIC state during post_load (rather than when the CPU
starts).

This allows an interrupt to be delivered from the ioapic to
the lapic prior to cpu loading, in particular the RTC that starts
ticking as soon as we load it's state.

Partially fixes a case where Windows hangs after migration due to RTC interrupts
disappearing; it survived ~30 iterations of my test where as without
it we didn't get to 2.  Still something else to be found yet.

Signed-off-by: Dr. David Alan Gilbert <address@hidden>
Suggested-by: Paolo Bonzini <address@hidden>
---
 hw/i386/kvm/apic.c   | 27 +++++++++++++++++++++++++--
 include/sysemu/kvm.h |  1 -
 target-i386/kvm.c    | 17 -----------------
 3 files changed, 25 insertions(+), 20 deletions(-)

diff --git a/hw/i386/kvm/apic.c b/hw/i386/kvm/apic.c
index 2bd0de8..343d250 100644
--- a/hw/i386/kvm/apic.c
+++ b/hw/i386/kvm/apic.c
@@ -28,9 +28,9 @@ static inline uint32_t kvm_apic_get_reg(struct 
kvm_lapic_state *kapic,
     return *((uint32_t *)(kapic->regs + (reg_id << 4)));
 }
 
-void kvm_put_apic_state(DeviceState *dev, struct kvm_lapic_state *kapic)
+static void kvm_put_apic_state(APICCommonState *s,
+                               struct kvm_lapic_state *kapic)
 {
-    APICCommonState *s = APIC_COMMON(dev);
     int i;
 
     memset(kapic, 0, sizeof(*kapic));
@@ -125,6 +125,26 @@ static void kvm_apic_vapic_base_update(APICCommonState *s)
     }
 }
 
+static void kvm_apic_put(void *data)
+{
+    APICCommonState *s = data;
+    struct kvm_lapic_state kapic;
+    int ret;
+
+    kvm_put_apic_state(s, &kapic);
+
+    ret = kvm_vcpu_ioctl(CPU(s->cpu), KVM_SET_LAPIC, &kapic);
+    if (ret < 0) {
+        fprintf(stderr, "KVM_SET_LAPIC failed: %s\n", strerror(ret));
+        abort();
+    }
+}
+
+static void kvm_apic_post_load(APICCommonState *s)
+{
+    run_on_cpu(CPU(s->cpu), kvm_apic_put, s);
+}
+
 static void do_inject_external_nmi(void *data)
 {
     APICCommonState *s = data;
@@ -178,6 +198,8 @@ static void kvm_apic_reset(APICCommonState *s)
 {
     /* Not used by KVM, which uses the CPU mp_state instead.  */
     s->wait_for_sipi = 0;
+
+    run_on_cpu(CPU(s->cpu), kvm_apic_put, s);
 }
 
 static void kvm_apic_realize(DeviceState *dev, Error **errp)
@@ -206,6 +228,7 @@ static void kvm_apic_class_init(ObjectClass *klass, void 
*data)
     k->set_base = kvm_apic_set_base;
     k->set_tpr = kvm_apic_set_tpr;
     k->get_tpr = kvm_apic_get_tpr;
+    k->post_load = kvm_apic_post_load;
     k->enable_tpr_reporting = kvm_apic_enable_tpr_reporting;
     k->vapic_base_update = kvm_apic_vapic_base_update;
     k->external_nmi = kvm_apic_external_nmi;
diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index c9c2436..ae5d81b 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -372,7 +372,6 @@ int kvm_irqchip_send_msi(KVMState *s, MSIMessage msg);
 
 void kvm_irqchip_add_irq_route(KVMState *s, int gsi, int irqchip, int pin);
 
-void kvm_put_apic_state(DeviceState *d, struct kvm_lapic_state *kapic);
 void kvm_get_apic_state(DeviceState *d, struct kvm_lapic_state *kapic);
 
 struct kvm_guest_debug;
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index d1a25c5..f1ad805 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -2416,19 +2416,6 @@ static int kvm_get_apic(X86CPU *cpu)
     return 0;
 }
 
-static int kvm_put_apic(X86CPU *cpu)
-{
-    DeviceState *apic = cpu->apic_state;
-    struct kvm_lapic_state kapic;
-
-    if (apic && kvm_irqchip_in_kernel()) {
-        kvm_put_apic_state(apic, &kapic);
-
-        return kvm_vcpu_ioctl(CPU(cpu), KVM_SET_LAPIC, &kapic);
-    }
-    return 0;
-}
-
 static int kvm_put_vcpu_events(X86CPU *cpu, int level)
 {
     CPUState *cs = CPU(cpu);
@@ -2670,10 +2657,6 @@ int kvm_arch_put_registers(CPUState *cpu, int level)
         if (ret < 0) {
             return ret;
         }
-        ret = kvm_put_apic(x86_cpu);
-        if (ret < 0) {
-            return ret;
-        }
     }
 
     ret = kvm_put_tscdeadline_msr(x86_cpu);
-- 
2.7.4