Re: VMX status report. Xen:26323 & Dom0:3.7.1

[David Vrabel <david.vrabel@citrix.com>]

On 14/01/13 16:14, Jan Beulich wrote:
>>>> On 14.01.13 at 17:03, David Vrabel <david.vrabel@citrix.com> wrote:
>> On 14/01/13 15:06, Andres Lagar-Cavilla wrote:
>>> @@ -288,7 +289,19 @@ static int mmap_batch_fn(void *data, void *state)
>>>  					 &cur_page);
>>>  
>>>  	/* Store error code for second pass. */
>>> -	*(st->err++) = ret;
>>> +	if (st->version == 1) {
>>> +		if (ret < 0) {
>>> +			/*
>>> +			 * V1 encodes the error codes in the 32bit top nibble of the
>>> +			 * mfn (with its known limitations vis-a-vis 64 bit callers).
>>> +			 */
>>> +			*mfnp |= (ret == -ENOENT) ?
>>> +						PRIVCMD_MMAPBATCH_PAGED_ERROR :
>>> +						PRIVCMD_MMAPBATCH_MFN_ERROR;
>>
>> You also need to clear the top nibble on success (ret >= 0) so large
>> PFNs with the top nibble already set don't give false positives of errors.
> 
> Not really - that's what v2 was added for (the caller, unless
> keeping a second array with the original MFNs, wouldn't be able
> to match things up in that case).

Ok, I can agree with that.

David