[Qemu-devel] [PATCH] KVM: Don't assume that mpstate exists with in-kernel PIC always

[Alexander Graf <agraf@suse.de>]

On PPC, we don't support MP state. So far it's not necessary and I'm
not convinced yet that we really need to support it ever.

However, the current idle logic in QEMU assumes that an in-kernel PIC
also means we support MP state. This assumption is not true anymore.

Let's split up the two cases into two different variables. That way
PPC can expose an in-kernel PIC, while not implementing MP state.

Signed-off-by: Alexander Graf <agraf@suse.de>
CC: Jan Kiszka <jan.kiszka@siemens.com>

---

v1 -> v2:

  - use kvm_halt_in_kernel() instead
---
 cpus.c               |    2 +-
 include/sysemu/kvm.h |   10 ++++++++++
 kvm-all.c            |    2 ++
 3 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/cpus.c b/cpus.c
index e919dd7..e626f7e 100644
--- a/cpus.c
+++ b/cpus.c
@@ -73,7 +73,7 @@ static bool cpu_thread_is_idle(CPUArchState *env)
         return true;
     }
     if (!cpu->halted || qemu_cpu_has_work(cpu) ||
-        kvm_async_interrupts_enabled()) {
+        kvm_halt_in_kernel()) {
         return false;
     }
     return true;
diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index 8a9ebda..07375bf 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -42,6 +42,7 @@
 extern bool kvm_allowed;
 extern bool kvm_kernel_irqchip;
 extern bool kvm_async_interrupts_allowed;
+extern bool kvm_halt_in_kernel_allowed;
 extern bool kvm_irqfds_allowed;
 extern bool kvm_msi_via_irqfd_allowed;
 extern bool kvm_gsi_routing_allowed;
@@ -72,6 +73,14 @@ extern bool kvm_gsi_routing_allowed;
 #define kvm_async_interrupts_enabled() (kvm_async_interrupts_allowed)
 
 /**
+ * kvm_supports_mpstate:
+ *
+ * Returns: true if the kvm side supports MP states which is
+ * required to indicate to kvm that a vcpu is currently halted
+ */
+#define kvm_halt_in_kernel() (kvm_halt_in_kernel_allowed)
+
+/**
  * kvm_irqfds_enabled:
  *
  * Returns: true if we can use irqfds to inject interrupts into
@@ -101,6 +110,7 @@ extern bool kvm_gsi_routing_allowed;
 #define kvm_enabled()           (0)
 #define kvm_irqchip_in_kernel() (false)
 #define kvm_async_interrupts_enabled() (false)
+#define kvm_halt_in_kernel() (false)
 #define kvm_irqfds_enabled() (false)
 #define kvm_msi_via_irqfd_enabled() (false)
 #define kvm_gsi_routing_allowed() (false)
diff --git a/kvm-all.c b/kvm-all.c
index 130cdbc..2e301f5 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -106,6 +106,7 @@ struct KVMState
 KVMState *kvm_state;
 bool kvm_kernel_irqchip;
 bool kvm_async_interrupts_allowed;
+bool kvm_halt_in_kernel_allowed;
 bool kvm_irqfds_allowed;
 bool kvm_msi_via_irqfd_allowed;
 bool kvm_gsi_routing_allowed;
@@ -1219,6 +1220,7 @@ static int kvm_irqchip_create(KVMState *s)
      * interrupt delivery (though the reverse is not necessarily true)
      */
     kvm_async_interrupts_allowed = true;
+    kvm_halt_in_kernel_allowed = true;
 
     kvm_init_irq_routing(s);
 
-- 
1.6.0.2