[Qemu-devel] Re: [PATCH 07/15] kvm: Separate TCG from KVM cpu execution

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2011-02-09 15:44, Marcelo Tosatti wrote:
> On Wed, Feb 09, 2011 at 08:59:23AM +0100, Jan Kiszka wrote:
>> On 2011-02-09 00:39, Marcelo Tosatti wrote:
>>> On Mon, Feb 07, 2011 at 12:19:18PM +0100, Jan Kiszka wrote:
>>>> Mixing up TCG bits with KVM already led to problems around eflags
>>>> emulation on x86. Moreover, quite some code that TCG requires on cpu
>>>> enty/exit is useless for KVM. So dispatch between tcg_cpu_exec and
>>>> kvm_cpu_exec as early as possible.
>>>>
>>>> The core logic of cpu_halted from cpu_exec is added to
>>>> kvm_arch_process_irqchip_events. Moving away from cpu_exec makes
>>>> exception_index meaningless for KVM, we can simply pass the exit reason
>>>> directly (only "EXCP_DEBUG vs. rest" is relevant).
>>>>
>>>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>>>> ---
>>>>  cpu-exec.c        |   19 ++++++-------------
>>>>  cpus.c            |   10 +++++-----
>>>>  kvm-all.c         |   19 +++++++++----------
>>>>  target-i386/kvm.c |    6 +++---
>>>>  4 files changed, 23 insertions(+), 31 deletions(-)
>>>>
>>>> diff --git a/target-i386/kvm.c b/target-i386/kvm.c
>>>> index ba183c4..377a0a3 100644
>>>> --- a/target-i386/kvm.c
>>>> +++ b/target-i386/kvm.c
>>>> @@ -1502,12 +1502,13 @@ int kvm_arch_post_run(CPUState *env, struct kvm_run *run)
>>>>  
>>>>  int kvm_arch_process_irqchip_events(CPUState *env)
>>>>  {
>>>> +    if (env->interrupt_request & (CPU_INTERRUPT_HARD | CPU_INTERRUPT_NMI)) {
>>>> +        env->halted = 0;
>>>> +    }
>>>
>>> Why is it necessary to clear env->halted here?
>>
>> Because we no longer come along cpu_halted() in cpu_exec(). This
>> corresponds to the tail of process_irqchip_events() in qemu-kvm
> 
> This is not yet well integrated, we probably don't need env->halted
> anymore (see cpu_has_work). Can be improved later though.

So far we check for it, at least in cpu_[thread_]is_idle. And that's a
generic service.

Jan

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