On 10/06/2017 02:19 PM, Paul Durrant wrote:
-----Original Message-----
From: Xen-devel [mailto:xen-devel-boun...@lists.xen.org] On Behalf Of
Ross Lagerwall
Sent: 06 October 2017 13:58
To: Ian Jackson <ian.jack...@citrix.com>; qemu-devel@nongnu.org
Cc: Anthony Perard <anthony.per...@citrix.com>; xen-
de...@lists.xenproject.org; Stefano Stabellini <sstabell...@kernel.org>;
Juergen Gross <jgr...@suse.com>
Subject: Re: [Xen-devel] [PATCH v2 0/*] xen: xen-domid-restrict
improvements
On 10/04/2017 05:18 PM, Ian Jackson wrote:
(Resending this because 1. I got the CC for xen-devel wrong; 2. I got
the subject wrong: there are actually 8 patches; 3. I mangled
Anthony's name in theheaders. Sorry for the noise.)
I have been working on trying to get qemu, when running as a Xen
device model, to _actually_ not have power equivalent to root.
I think I have achieved this, with some limitations (which will be
discussed in my series against xen.git.
However, there are changes to qemu needed. In particular
* The -xen-domid-restrict option does not work properly right now.
It only restricts a small subset of the descriptors qemu has open.
I am introducing a new library call in the Xen libraries for this,
xentoolcore_restrict_all.
Hi Ian,
I'm testing your QEMU and Xen patch series and found that after being
restricted, QEMU fails to setup up the VGA memory properly which causes
a complete stall with stdvga. With cirrus it mostly works although it
seems to have reduced performance.
I think it happens when the VM sets up the BAR some time after
xen_restrict() has been called. The failure comes from QEMU calling
xc_domain_add_to_physmap() which calls do_memory_op() and finally
xencall2(). But the underlying xencall fd has been replaced with /dev/null.
Oh, that's a PITA. This is because of the slightly hacky way that the VRAM is
dealt with (it needing to be moved into the BAR of the PCI VGA device at the
point where guest firmware programs it). Maybe we need a new dm_op for this?
If no one objects, I propose adding the following calls to
libxendevicemodel (with underlying Xen implementations, of course) that
would be usable after the xendevicemodel handle has been restricted.
xendevicemodel_add_to_physmap(xendevicemodel_handle *dmod,
domid_t domid,
unsigned long idx,
xen_pfn_t gpfn);
This is equivalent to xc_domain_add_to_physmap() with
space==XENMAPSPACE_gmfn.
xendevicemodel_pin_memory_cacheattr(xendevicemodel_handle *dmod,
domid_t domid,
uint64_t start,
uint64_t end,
uint32_t type);
This is equivalent to xc_domain_pin_memory_cacheattr().
--
Ross Lagerwall
