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[Qemu-devel] [PATCH v1 for-2.12] s390x/kvm: call cpu_synchronize_state()

From: David Hildenbrand
Subject: [Qemu-devel] [PATCH v1 for-2.12] s390x/kvm: call cpu_synchronize_state() on every kvm_arch_handle_exit()
Date: Fri, 6 Apr 2018 11:35:52 +0200

Manually having to use cpu_synchronize_state() is error prone. And as
Christian Borntraeger discovered, e.g. handle_diag() is currently
missing a cpu_synchronize_state(), as decode_basedisp_s() uses a
general purpose register value internally.

So let's do an overall cpu_synchronize_state(), which fixes at least the
one mentioned BUG. We will clean up the superfluous cpu_synchronize_state()
calls later.

We now also call it (although maybe not neded) for
- KVM_EXIT_S390_RESET -> s390_reipl_request()
- KVM_EXIT_DEBUG -> kvm_arch_handle_debug_exit()
- unmanagable/unimplemented intercepts
- ICPT_CPU_STOP -> do_stop_interrupt() -> cpu gets halted
- Scenarios where we inject an operation exception
- handle_stsi()

I don't think any of these are performance critical. Especially as we
have all information directly contained in kvm_run, there are no
additional IOCTLs to issue on modern kernels.

Signed-off-by: David Hildenbrand <address@hidden>
 target/s390x/kvm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
index f570896dc1..fb59d92def 100644
--- a/target/s390x/kvm.c
+++ b/target/s390x/kvm.c
@@ -1778,6 +1778,8 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run 
+    cpu_synchronize_state(cs);
     switch (run->exit_reason) {
         case KVM_EXIT_S390_SIEIC:
             ret = handle_intercept(cpu);

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