Re: [PATCH v2] sync CPU state upon final domain destruction

[Julien Grall <julien.grall@linaro.org>]

Hi,

On 11/22/2017 01:00 PM, Jan Beulich wrote:
>>>> On 22.11.17 at 13:39, <JBeulich@suse.com> wrote:
>> See the code comment being added for why we need this.
>>
>> This is being placed here to balance between the desire to prevent
>> future similar issues (the risk of which would grow if it was put
>> further down the call stack, e.g. in vmx_vcpu_destroy()) and the
>> intention to limit the performance impact (otherwise it could also go
>> into rcu_do_batch(), paralleling the use in do_tasklet_work()).
>>
>> Reported-by: Igor Druzhinin <igor.druzhinin@citrix.com>
>> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> 
> I'm sorry, Julien, I did forget to Cc you (for 4.10 inclusion).

Release-acked-by: Julien Grall <julien.grall@linaro.org>

Cheers,

> 
>> ---
>> v2: Move from vmx_vcpu_destroy() to complete_domain_destroy().
>>
>> --- a/xen/common/domain.c
>> +++ b/xen/common/domain.c
>> @@ -794,6 +794,14 @@ static void complete_domain_destroy(stru
>>       struct vcpu *v;
>>       int i;
>>   
>> +    /*
>> +     * Flush all state for the vCPU previously having run on the current CPU.
>> +     * This is in particular relevant for x86 HVM ones on VMX, so that this
>> +     * flushing of state won't happen from the TLB flush IPI handler behind
>> +     * the back of a vmx_vmcs_enter() / vmx_vmcs_exit() section.
>> +     */
>> +    sync_local_execstate();
>> +
>>       for ( i = d->max_vcpus - 1; i >= 0; i-- )
>>       {
>>           if ( (v = d->vcpu[i]) == NULL )
> 
> 
> 
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