[help]: handling IO instructions for hybrid

[help]: handling IO instructions for hybrid

[Mukesh Rathor]

Hi all,

I am figuring io access for hybrid guests, dom0 and domU. I see that there
are two ways: PV -> emulate_privileged_op(), or hvm handles via 
handle_mmio()/handle_pio(). I am not familiar with either one, and would
help me lot if anybody expert in that can suggest which way 
hybrid should go, both dom0 and domU. Any suggestions would help. If
there are any docs on this, that would be great too.

thanks,
Mukesh

Re: [help]: handling IO instructions for hybrid

[Keir Fraser]

On 07/02/2012 02:26, "Mukesh Rathor" <mukesh.rathor@oracle.com> wrote:

> 
> Hi all,
> 
> I am figuring io access for hybrid guests, dom0 and domU. I see that there
> are two ways: PV -> emulate_privileged_op(), or hvm handles via
> handle_mmio()/handle_pio(). I am not familiar with either one, and would
> help me lot if anybody expert in that can suggest which way
> hybrid should go, both dom0 and domU. Any suggestions would help. If
> there are any docs on this, that would be great too.

Probably the PV route, for dom0 and domU. Really most things you want to do,
the PV route is going to be the right way (unless you are PVHVM'ing certain
things, e.g., like using EPT assistance for pagetable handling).

 -- Keir

> thanks,
> Mukesh
> 

Re: [help]: handling IO instructions for hybrid

[Mukesh Rathor]

On Mon, 06 Feb 2012 19:41:23 +0000
Keir Fraser <keir.xen@gmail.com> wrote:

> On 07/02/2012 02:26, "Mukesh Rathor" <mukesh.rathor@oracle.com> wrote:
> > 
> > I am figuring io access for hybrid guests, dom0 and domU. I see
> > that there are two ways: PV -> emulate_privileged_op(), or hvm
> > handles via handle_mmio()/handle_pio(). I am not familiar with
> > either one, and would help me lot if anybody expert in that can
> > suggest which way hybrid should go, both dom0 and domU. Any
> > suggestions would help. If there are any docs on this, that would
> > be great too.
> 
> Probably the PV route, for dom0 and domU. Really most things you want
> to do, the PV route is going to be the right way (unless you are
> PVHVM'ing certain things, e.g., like using EPT assistance for
> pagetable handling).
> 
>  -- Keir

Thanks Keir. Just to confirm, the hybrid should continue to request
iopl of 1, right?

Mukesh

Re: [help]: handling IO instructions for hybrid

[Keir Fraser]

On 08/02/2012 18:17, "Mukesh Rathor" <mukesh.rathor@oracle.com> wrote:

> On Mon, 06 Feb 2012 19:41:23 +0000
> Keir Fraser <keir.xen@gmail.com> wrote:
> 
>> On 07/02/2012 02:26, "Mukesh Rathor" <mukesh.rathor@oracle.com> wrote:
>>> 
>>> I am figuring io access for hybrid guests, dom0 and domU. I see
>>> that there are two ways: PV -> emulate_privileged_op(), or hvm
>>> handles via handle_mmio()/handle_pio(). I am not familiar with
>>> either one, and would help me lot if anybody expert in that can
>>> suggest which way hybrid should go, both dom0 and domU. Any
>>> suggestions would help. If there are any docs on this, that would
>>> be great too.
>> 
>> Probably the PV route, for dom0 and domU. Really most things you want
>> to do, the PV route is going to be the right way (unless you are
>> PVHVM'ing certain things, e.g., like using EPT assistance for
>> pagetable handling).
>> 
>>  -- Keir
> 
> Thanks Keir. Just to confirm, the hybrid should continue to request
> iopl of 1, right?

I'm not sure it matters since the hybrid guest runs in ring 0 of non-root
context I believe? Since ring 1 is in that case unused, it doesn't matter
whether iopl is 0 or 1.

 -- Keir