RE: [Xen-ia64-devel] [PATCH] bug fix new_tlbflush_clock_period()

["Xu, Anthony" <anthony.xu@xxxxxxxxx>]

Isaku Yamahata write on 2007年2月5日 11:43:
> On Mon, Feb 05, 2007 at 11:34:59AM +0800, Xu, Anthony wrote:
>> Before calling local_vhpt_flush,
>> We need to make sure it is not VTI-domain and it is not per-VCPU
>> VHPT, 
> 
> local_vhpt_flush() always flushes vhpt associated to pcpu. not vcpu.

If HAS_PERVCPU_VHPT(current->domain) is true, or VMX_DOMAIN (current) is true.

Vhpt_paddr may be 0,
So It erases 64KB memory content that starts from machine address 0.


- Anthony

> 
> DEFINE_PER_CPU (unsigned long, vhpt_paddr);
> DEFINE_PER_CPU (unsigned long, vhpt_pend);
> local_vhpt_flush(void)
>         __vhpt_flush(__ia64_per_cpu_var(vhpt_paddr));
> 
> 
>> +static void
>> +tlbflush_clock_local_flush(void *unused)
>> +{
>> 
>>>> if(!VMX_DOMAIN(current)&&!HAS_PERVCPU_VHPT(current->domain){ +   
>>>>    local_vhpt_flush(); }
>> +    local_flush_tlb_all();
>> +}
>> +
>> 
>> - Anthony
>> 
>> Isaku Yamahata write on 2007年2月5日 10:56:
>>> On Mon, Feb 05, 2007 at 10:02:53AM +0800, Xu, Anthony wrote:
>>>> Isaku Yamahata write on 2007年2月5日 9:45:
>>>>> Hi Kouya.
>>>>> Good catch!
>>>>> Although this patch already commited and I made the bug,
>>>>> vti domain also relies on tlb flush lock.
>>>>> (See flush_vtlb_for_context_switch())
>>>>> 
>>>>> So we should do
>>>>>   if (!test_bit(_VCPUF_initialize))
>>>>>   continue
>>>>>   if (VMX_DOMAIN(v))
>>>>>   <flush all hash and collision chain of v>
>>>>>   else
>>>>>   vcpu_vhpt_flush()
>>>>> 
>>>>> Or
>>>>> 
>>>>>   disable the tlb flush clock usage in
>>>>> flush_vtlb_for_context_switch().
>>>>> 
>>>> 
>>>> Hi Isaku,
>>>> 
>>>> Why do we need to call vcpu_vhpt_flush?
>>>> IMO we only need to call __local_flush_tlb_all, if we use per-vcpu
>>>> VHPT. Can you elaborate it?
>>> 
>>> That's right.
>>> when I wrote that, I tried to apply tlb flush clock to
>>> not only mTLB and vhpt but also per-vcpu vhpt. but it isn't
>>> used for per-vcpu vhpt. So I removed the related bogus code.

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