From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Vrabel <david.vrabel@citrix.com>
Subject: Re: VMX status report. Xen:26323 & Dom0:3.7.1
Date: Mon, 14 Jan 2013 16:15:46 +0000
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To: Jan Beulich <JBeulich@suse.com>
Cc: Yongjie Ren <yongjie.ren@intel.com>, Ian Campbell <Ian.Campbell@citrix.com>, Konrad Wilk <konrad.wilk@oracle.com>, Mats Petersson <mats.petersson@citrix.com>, xen-devel <xen-devel@lists.xen.org>, Chao Zhou <chao.zhou@intel.com>, Andres Lagar-Cavilla <andreslc@gridcentric.ca>, Yan Dai <yan.dai@intel.com>, YongweiX Xu <yongweix.xu@intel.com>, Andres Lagar-Cavilla <andres.lagarcavilla@gmail.com>, SongtaoX Liu <songtaox.liu@intel.com>, AndresLagar-Cavilla <andres@lagarcavilla.org>
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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