Re: [PATCH] KVM: VMX: Fix locking order in handle_invalid_guest_state

[Jan Kiszka <jan.kiszka@web.de>]

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Marcelo Tosatti wrote:
> On Wed, Jul 22, 2009 at 11:53:26PM +0200, Jan Kiszka wrote:
>> Release and re-acquire preemption and IRQ lock in the same order as
>> vcpu_enter_guest does.
> 
> This should happen in vcpu_enter_guest, before it decides to disable
> preemption/irqs (so you consolidate the control there).

Maybe, maybe not. handle_invalid_guest_state is an alternative way of
"executing" guest code, and it currently shares the setup and tear-down
with vmx_vcpu_run. If it has to share parts that actually require
preemption and IRQ lock, then moving makes not much sense. Can anyone
comment on what the requirements for handle_invalid_guest_state are?

I would suggest to merge this fix first and then decide about and
potentially merge a refactoring patch.

Jan

> 
> Maybe add a new member to x86_ops?
> 
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>> ---
>>
>>  arch/x86/kvm/vmx.c |    4 ++--
>>  1 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index d75c271..4f914c3 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -3324,8 +3324,8 @@ static void handle_invalid_guest_state(struct kvm_vcpu *vcpu,
>>  	struct vcpu_vmx *vmx = to_vmx(vcpu);
>>  	enum emulation_result err = EMULATE_DONE;
>>  
>> -	preempt_enable();
>>  	local_irq_enable();
>> +	preempt_enable();
>>  
>>  	while (!guest_state_valid(vcpu)) {
>>  		err = emulate_instruction(vcpu, kvm_run, 0, 0, 0);
>> @@ -3344,8 +3344,8 @@ static void handle_invalid_guest_state(struct kvm_vcpu *vcpu,
>>  			schedule();
>>  	}
>>  
>> -	local_irq_disable();
>>  	preempt_disable();
>> +	local_irq_disable();
>>  
>>  	vmx->invalid_state_emulation_result = err;
>>  }
>>
> 
> 



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