From mboxrd@z Thu Jan  1 00:00:00 1970
From: Simon Martin <furryfuttock@gmail.com>
Subject: Re: Consuming PCI device in PV kernel
Date: Fri, 25 Jul 2014 15:36:30 +0100
Message-ID: <263120224.20140725153630@gmail.com>
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	<20140718190942.GG15947@laptop.dumpdata.com>
	<538610044.20140721111330@gmail.com>
	<1405940004.25022.10.camel@kazak.uk.xensource.com>
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	<1406293821.24842.8.camel@kazak.uk.xensource.com>
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	<53D2609A.4000802@citrix.com> <13170235.20140725152048@gmail.com>
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To: Ian Campbell <Ian.Campbell@citrix.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>, xen-devel@lists.xen.org
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Hello Ian,

>> > Once you grant map a page from another domain, your domain no longer
>> > owns the PTE.  You should either avoid that PTE, or grant unmap the
>> > foreign frame first.
>> 
>> I  have  not  grant mapped this. I have just called update_va_mapping.
>> Should I be using grant?

> Andrew is saying that the mapping which is currently at the virtual
> address is *already* a grant mapping, not that you are trying to grant
> map something here. Grant maps need to be unmapped with the grant unmap
> hypercall, not just by rewriting the PTE. (IIRC).

> You should not be using grants to map PCI IO space, no.

Thanks  Ian. I'm off traveling next week so I'll pick up on this again
in August. I wonder what has grant mapped this memory area....

-- 
Best regards,
 Simon                            mailto:furryfuttock@gmail.com