Re: [Xen-devel] VMX status report. Xen:26323 & Dom0:3.7.1

[David Vrabel <david.vrabel@xxxxxxxxxx>]

On 14/01/13 16:14, Jan Beulich wrote:
>>>> On 14.01.13 at 17:03, David Vrabel <david.vrabel@xxxxxxxxxx> 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

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