9:43 p.m.
Hi Jan,
Thanks for the confirmation to proceed on project proposal.
Also, I tried installing Jailhouse on my VM after enabling VT-x/EPT and
IOMMU for my VM(Guest OS- Ubuntu 18.04) on VMware fusion hypervisor with
MacOS on the host side.
However, Jailhouse hardware check was failed because of missing
*Preemption timer
and Virtualize APIC access*, could you please suggest, if this is hardware
limitation? Is there any workaround here?
My laptop's processor is Intel quad-core i7.
[image: image.png]
Also, could you please suggest, if I can talk to you through an IRC or
slack channel since it is a bit hard to communicate over email every time.
Thanks,
Prakhar
On Mon, Mar 30, 2020 at 6:15 AM Jan Kiszka <jan.kiszka(a)web.de> wrote:
On 30.03.20 10:02, PRAKHAR BANSAL wrote:
> Hi Jan,
>
> On Sat, Mar 28, 2020 at 4:12 AM Jan Kiszka <jan.kiszka(a)web.de
> <mailto:jan.kiszka@web.de>> wrote:
>
> On 28.03.20 08:47, PRAKHAR BANSAL wrote:
> > Hi Jan,
> >
> > Thanks for the reply!
> >
> > I was only considering the command-line tool "code" for
reference
> to the
> > Jailhouse kernel API(ioctl calls) because I didn't find a
> documentation
> > of the Jailhouse kernel APIs.
>
> Right, the IOCTL API is not documented so far. It is currently only
used
> inside the Jailhouse project. This needs to be formalized when there
> shall be external users like a libvirt driver.
>
> That might be a nice small contribution task: Create some
> Documentation/driver-interfaces.md that describes the IOCTLs along
with
> their parameter structures and that also includes the current
> sysfs-entries.txt as a section. Then send this as patch here. I'll
help
> out when details are not clear from reading the code.
>
> Sure. I will do that.
>
> >
> > For the second part as you mentioned that Jailhouse can only
create
> > cells with the constraints defined in the root cell
configuration. I
> > have a few questions regarding that.
> >
> > 1. Is there a way to know if Jailhouse is enabled on the host and
get
> > the root cell configuration(s) from Jailhouse through an API?
> This can
> > be used while binding the libvirt to the Jailhouse hypervisor.
>
> Look at
>
https://github.com/siemens/jailhouse/blob/master/Documentation/sysfs-entr...
> for what is reported as runtime information. Full configurations
can't
> be read back at this point. This might be reconsidered in the light
of
> [1], but I wouldn't plat for that yet.
>
>
> Ok, sure. I am looking into it.
>
>
> >
> > 2. If Jailhouse is not enabled(again can we know this using some
API)
> > then, can libvirt enable/disable Jailhouse during the libvirt
> binding of
> > the Jailhouse driver with a given set of Jailhouse cell
> configurations
> > describing a complete partitioned system?
>
> With the API above and a given configuration set, yes. The config set
> would have to be provided to the libvirt driver in some to-be-defined
> way (e.g. /etc/libvirt/jailhouse.conf ->
/etc/libvirt/jailhouse/*.cell).
>
> Cool, got it. Thanks!
>
> >
> > 3. I was wondering, as you mentioned that libvirt driver should
check
> > for mismatch of the cell configuration with the root cell
> configuration,
> > the question is, isn't that done by Jailhouse itself? If yes, then
> > libvirt can just pass on the cell creation requests to Jailhouse
and
> > return the response to the user as it is, rather than driver
> doing any
> > such mismatch check.
>
> With matching I'm referring to a libvirt user request like "create a
> domain with 2 CPUs", while there are no cells left that have more
than
> one CPU. Or "give the domain 1G RAM", and you need to find an
available
> cell with that much memory. Those are simple examples. A request that
> states "connect the domain to the host network A" implies that a cell
> has a shared-memory link to, say, the root cell that can be
configured
> to bridge this. But let's keep that for later and start as simple as
> possible.
>
>
> Do I need to match the libvirt user-requested cell config with only root
> cells or with all cells present at that time?
With all non-root cells - the root cell will be occupied already (it
runs libvirt e.g.).
>
> I wanted to request you for a favor for the proposal as the deadline is
> approaching. Could I prepare a proposal for this project based on our
> discussion here and improve it later based on feedback comments after
> the deadline? I understand that I got late in starting on the project
> search and selection.
Sure, please go ahead.
Jan
>
> Thanks,
> Prakhar
>
>
> Jan
>
> [1]
>
https://groups.google.com/d/msgid/jailhouse-dev/CADiTV-1QiRhSWZnw%2BkHhJM...
>
> >
> > -Prakhar
> >
> > On Thu, Mar 26, 2020 at 1:49 AM Jan Kiszka <jan.kiszka(a)web.de
> <mailto:jan.kiszka@web.de>
> > <mailto:jan.kiszka@web.de <mailto:jan.kiszka@web.de>>>
wrote:
> >
> > Hi Prakhar,
> >
> > On 25.03.20 05:36, PRAKHAR BANSAL wrote:
> > > Hi Jan,
> > >
> > > Thanks for the reply. I looked deeper into the libvirt and
> Jailhouse
> > > source code and found following two things that seem
> relevant to the
> > > project I am interested in.
> > >
> > > - Libvirt driver interface at [libvirt.git]
> > > <https://libvirt.org/git/?p=libvirt.git;a=tree;hb=HEAD> /
src
> > >
> <https://libvirt.org/git/?p=libvirt.git;a=tree;f=src;hb=HEAD> /
> > driver.h
> > >
> >
> <
https://libvirt.org/git/?p=libvirt.git;a=blob_plain;f=src/driver.h;hb=HEAD
>
> > > - Jailhouse tool, which is using the ioctl API of the
> Jailhouse,
> > > available at
> > >
> https://github.com/siemens/jailhouse/blob/master/tools/jailhouse.c.
> > >
> > > With the help of the above two, it looks like, a libvirt
> driver
> > for the
> > > Jailhouse can be implemented. Let me know if I am moving
> in the right
> > > direction so far.
> >
> > From the Jailhouse perspective, it is important to not
> consider the
> > command line tool an interface anymore (like in the first
> prototype) but
> > build on top of the Linux driver API (ioctls, sysfs). There
> is already a
> > Python library which started to abstract this interface for
> > Jailhouse-internal use cases. However, I strongly suspect
> libvirt will
> > rather want a native binding.
> >
> > >
> > > I have been looking at the other libvirt driver
> implementations for
> > > hypervisors like HyperV and VMware to understand their
> implementation
> > > and learn from there.
> >
> > As Jailhouse is a static partitioning hypervisor without
> abstraction of
> > the underlying hardware, your starting point for the libvirt
> binding
> > should be a given set of Jailhouse cell configurations
> describing a
> > complete partitioned system. So rather than instantiating on
> demand a
> > domain (Jailhouse cell) with, say, a network adapter, the
> driver should
> > match a user request for a domain against the configuration
> set and use
> > what is there - or report the mismatch. What it could
> organize, though,
> > is interconnecting cells that have a (preconfigured) virtual
> network
> > link to the root cell.
> >
> > Due to this different concept, there will be no 1:1 mapping
for
> > commodity hypervisor drivers to the Jailhouse scenario.
> Still, studying
> > what they do is useful and needed in order to understand what
> "normally"
> > happens and find a reasonable translation. This is probably
> the most
> > challenging part of the project.
> >
> > Jan
> >
>
