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Message-Id: <20100504124634.399797233@redhat.com>
Date: Tue, 04 May 2010 09:45:23 -0300
From: Marcelo Tosatti <mtosatti@redhat.com>
References: <20100504124518.979470863@redhat.com>
Content-Disposition: inline; filename=cpu-sync-state-use-run-on-cpu
Subject: [Qemu-devel] [patch uq/master 5/9] kvm: synchronize state from cpu
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To: kvm@vger.kernel.org, qemu-devel@nongnu.org
Cc: Marcelo Tosatti <mtosatti@redhat.com>

From: Jan Kiszka <jan.kiszka@siemens.com>

It is not safe to retrieve the KVM internal state of a given cpu
while its potentially modifying it.

Queue the request to run on cpu context, similarly to qemu-kvm.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: qemu/kvm-all.c
===================================================================
--- qemu.orig/kvm-all.c
+++ qemu/kvm-all.c
@@ -796,14 +796,22 @@ void kvm_flush_coalesced_mmio_buffer(voi
 #endif
 }
 
-void kvm_cpu_synchronize_state(CPUState *env)
+static void do_kvm_cpu_synchronize_state(void *_env)
 {
+    CPUState *env = _env;
+
     if (!env->kvm_vcpu_dirty) {
         kvm_arch_get_registers(env);
         env->kvm_vcpu_dirty = 1;
     }
 }
 
+void kvm_cpu_synchronize_state(CPUState *env)
+{
+    if (!env->kvm_vcpu_dirty)
+        run_on_cpu(env, do_kvm_cpu_synchronize_state, env);
+}
+
 void kvm_cpu_synchronize_post_reset(CPUState *env)
 {
     kvm_arch_put_registers(env, KVM_PUT_RESET_STATE);