Re: [PATCH] get rid of mmu_only parameter in emulator_write_emulated()

[Avi Kivity <avi@redhat.com>]

On 04/13/2010 10:26 AM, Gleb Natapov wrote:
> On Tue, Apr 13, 2010 at 10:24:40AM +0300, Avi Kivity wrote:
>    
>> On 04/13/2010 10:21 AM, Gleb Natapov wrote:
>>      
>>> May be I am missing something here, but it seams we can call
>>> kvm_mmu_pte_write() directly from emulator_cmpxchg_emulated()
>>> instead of passing mmu_only down to emulator_write_emulated_onepage()
>>> and call it there.
>>>
>>>
>>> @@ -3460,7 +3444,9 @@ static int emulator_cmpxchg_emulated(unsigned long addr,
>>>   	if (!exchanged)
>>>   		return X86EMUL_CMPXCHG_FAILED;
>>>
>>> -	return __emulator_write_emulated(addr, new, bytes, vcpu, true);
>>> +	kvm_mmu_pte_write(vcpu, gpa, new, bytes, 1);
>>> +
>>> +	return X86EMUL_CONTINUE;
>>>
>>>        
>> The written range might cross a page boundary, which
>> kvm_mmu_pte_write() is not prepared to handle.
>>
>>      
> Don't we emulate exchange as write in this case?
>
> 	if (((gpa + bytes - 1)&  PAGE_MASK) != (gpa&  PAGE_MASK))
> 		goto emul_write;
>    

We do, but that's unrelated.  We still have to invalidate potential ptes 
on both pages

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.