Re: [win-pv-devel] XcGnttabMapForeignPages function fails

[Gaurav Khuntale <gauravkhuntale@xxxxxxxxx>]

Hello Paul,

Thanks for your help and sorry for delayed response. We solved the issue which was in our custom driver in domain 0.

But now XcGnttabMapForeignPages() function is failing with error code STATUS_INVALID_PARAMETER if we call this function twice to map two different grant pages which are allocated in domain 0.

The second call to XcGnttabMapForeignPages() always fails with the same error.

From the xeniface driver logs, it seems that function is failing at FindGnttabIrp() api in IoctlGnttabPermitForeignAccess().

Is there anything like, we can not map two different pages in the same process?

Kindly help me to understand the reason behind above issue.

Thanks,

Gaurav

On Fri, Sep 9, 2016 at 2:41 PM, Paul Durrant <Paul.Durrant@xxxxxxxxxx> wrote:

‘xl debug-keys g’ should do what you want, I think.

 

  Paul

 

From: Gaurav Khuntale [mailto:gauravkhuntale@gmail.com]
Sent: 07 September 2016 15:58
To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
Cc: win-pv-devel@lists.xenproject.org
Subject: Re: [win-pv-devel] XcGnttabMapForeignPages function fails

 

Hello Paul,

 

Thank you for your reply.

 

Can you please tell me any way to check grant table of the domain?

 

Thanks,

Gaurav

 

On Wed, Sep 7, 2016 at 4:19 PM, Paul Durrant <Paul.Durrant@xxxxxxxxxx> wrote:

Hi,

 

  There should be no difference. If the page is present in the grant table of the domain that you’re attempting to map it from then you should be able to access it. The OS running in the domain should have no bearing (unless its interaction with Xen is buggy or limited in some way).

 

  Paul

 

From: win-pv-devel [mailto:win-pv-devel-bounces@lists.xenproject.org] On Behalf Of Gaurav Khuntale
Sent: 06 September 2016 19:30
To: win-pv-devel@lists.xenproject.org
Subject: [win-pv-devel] XcGnttabMapForeignPages function fails

 

Hello Folks,

 

For learning purpose i am trying things with event-channel and grant pages on Xen.

 

The problem currently i am facing is, XcGnttabMapForeignPages() function fails to map grant pages which are shared from domain 0 with error code as 31(0x1f). To share pages from domain 0, i am using xc_gntshr_share_pages() function.

 

When i tried to map grant pages into the windows guest domain which are shared from other windows guest domain then same function XcGnttabMapForeignPages() works perfectly.

 

Can anyone please help me to understand why i am observing such a behavior? Does grant page sharing not supported across the different operating system?

 

Thanks in advance.

 

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