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Date: Fri, 23 Aug 2013 15:58:47 +0300
From: Gleb Natapov <gleb@redhat.com>
Message-ID: <20130823125846.GE15513@redhat.com>
References: <1377260760-32056-1-git-send-email-james.hogan@imgtec.com>
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In-Reply-To: <1377260760-32056-1-git-send-email-james.hogan@imgtec.com>
Subject: Re: [Qemu-devel] [PATCH] kvm: sync cpu state on internal error
	before dump
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To: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, qemu-devel@nongnu.org, kvm@vger.kernel.org

On Fri, Aug 23, 2013 at 01:26:00PM +0100, James Hogan wrote:
> When a KVM internal error occurs QEMU dumps the CPU state, however it
> doesn't synchronise the state from KVM first so the dumped state is out
> of date. Add the synchronisation calls before the dump in both locations
> (which is used depends on whether the arch says to stop or not).
> 
x86_cpu_dump_state() calls cpu_synchronize_state() already.

> Note that x86 does a sync in its kvm_arch_stop_on_emulation_error()
> function so at least for emulation errors is unaffected.
> 
> Signed-off-by: James Hogan <james.hogan@imgtec.com>
> Cc: Gleb Natapov <gleb@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: kvm@vger.kernel.org
> ---
>  kvm-all.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/kvm-all.c b/kvm-all.c
> index b788fcd..803141a 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -1546,6 +1546,7 @@ static int kvm_handle_internal_error(CPUState *cpu, struct kvm_run *run)
>      if (run->internal.suberror == KVM_INTERNAL_ERROR_EMULATION) {
>          fprintf(stderr, "emulation failure\n");
>          if (!kvm_arch_stop_on_emulation_error(cpu)) {
> +            kvm_cpu_synchronize_state(cpu);
>              cpu_dump_state(cpu, stderr, fprintf, CPU_DUMP_CODE);
>              return EXCP_INTERRUPT;
>          }
> @@ -1701,6 +1702,7 @@ int kvm_cpu_exec(CPUState *cpu)
>      } while (ret == 0);
>  
>      if (ret < 0) {
> +        kvm_cpu_synchronize_state(cpu);
>          cpu_dump_state(cpu, stderr, fprintf, CPU_DUMP_CODE);
>          vm_stop(RUN_STATE_INTERNAL_ERROR);
>      }
> -- 
> 1.8.1.2
> 

--
			Gleb.