Re: [coreboot] VT-d support

[Zoran Stojsavljevic]

> `src/northbridge/intel/sandybridge/iommu.c` and acpi_fill_dmar() in
> `src/northbridge/intel/sandybridge/acpi.c`.

I'll be back!  ;-)

Zoran

On Mon, Jun 5, 2017 at 8:22 PM, Nico Huber  wrote:

> On 05.06.2017 19:47, Zoran Stojsavljevic wrote:
> >> If you are lucky, you only need to add 20~30 lines to your chipset's
> code.
> >
> > Could you, please, show us an explicit example (of these 20 to 30 lines
> of
> > code)?!
>
> `src/northbridge/intel/sandybridge/iommu.c` and acpi_fill_dmar() in
> `src/northbridge/intel/sandybridge/acpi.c`.
>
> Nico
>
>
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Re: [coreboot] VT-d support

[Nico Huber]

On 05.06.2017 19:47, Zoran Stojsavljevic wrote:
>> If you are lucky, you only need to add 20~30 lines to your chipset's code.
> 
> Could you, please, show us an explicit example (of these 20 to 30 lines of
> code)?!

`src/northbridge/intel/sandybridge/iommu.c` and acpi_fill_dmar() in
`src/northbridge/intel/sandybridge/acpi.c`.

Nico


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Re: [coreboot] VT-d support

[Zoran Stojsavljevic]

> If you are lucky, you only need to add 20~30 lines to your chipset's code.

Could you, please, show us an explicit example (of these 20 to 30 lines of
code)?!

Zoran

On Mon, Jun 5, 2017 at 7:34 PM, Nico Huber  wrote:

> Hi,
>
> On 05.06.2017 18:58, Himanshu Chauhan wrote:
> >
> >> On 05-Jun-2017, at 10:19 PM, ron minnich  wrote:
> >>
> >> The reason I ask about what you need is that on chromebooks the main
> >> coreboot support came down to 'don't disable anything’.
> >
> > I think its can’t just be disabled. Its just that kernel is not given
> > any knowledge about its existence. This is what I want to know. The
> > commercial BIOSes give an option of “enable VT-d” support. What do they
> > do when this option is selected? Can this be implemented in Coreboot?
> > This probably brings me to your next question of what is required. I
> > would spend some time to figure that out.
>
> First thing, the firmware doesn't have to support it. It's only that
> Intel chose _not_ to write per platform OS drivers and let the firm-
> ware do the abstraction instead (I know a kernel that works pretty well
> with VT-d even if there are no DMAR tables).
>
> coreboot already handles VT-d support on some chipsets (GM45, Sandy/
> Ivy Bridge come to mind). You can look how it's done there. If you are
> lucky, you only need to add 20~30 lines to your chipset's code.
>
> If your chipset needs special initialization, it's most probably docu-
> mented in the BIOS Writer's Guide (BWG) or BIOS Specification. Though,
> you need an NDA with Intel to get these.
>
> Nico
>
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Re: [coreboot] VT-d support

[ron minnich]

On Mon, Jun 5, 2017 at 10:33 AM Himanshu Chauhan 
wrote:

>
> > oh, really? Why do you think that? Have you looked at the relevant MSR
> and what is the basis of your claim?
>
> I was just guessing what it could be. :)
>
>
I think it's a ton easier if you study on some simple hypervisors written
for VMX, it's a lot easier to know than to guess.
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Re: [coreboot] VT-d support

[Himanshu Chauhan]

> On 05-Jun-2017, at 10:50 PM, ron minnich  wrote:
> 
> 
> 
> On Mon, Jun 5, 2017 at 9:58 AM Himanshu Chauhan  
> wrote:
> 
> I think its can’t just be disabled.
> 
> oh, really? Why do you think that? Have you looked at the relevant MSR and 
> what is the basis of your claim?

I was just guessing what it could be. :)

> 
> ron 


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Re: [coreboot] VT-d support

[Nico Huber]

Hi,

On 05.06.2017 18:58, Himanshu Chauhan wrote:
> 
>> On 05-Jun-2017, at 10:19 PM, ron minnich  wrote:
>>
>> The reason I ask about what you need is that on chromebooks the main
>> coreboot support came down to 'don't disable anything’. 
> 
> I think its can’t just be disabled. Its just that kernel is not given
> any knowledge about its existence. This is what I want to know. The
> commercial BIOSes give an option of “enable VT-d” support. What do they
> do when this option is selected? Can this be implemented in Coreboot?
> This probably brings me to your next question of what is required. I
> would spend some time to figure that out.

First thing, the firmware doesn't have to support it. It's only that
Intel chose _not_ to write per platform OS drivers and let the firm-
ware do the abstraction instead (I know a kernel that works pretty well
with VT-d even if there are no DMAR tables).

coreboot already handles VT-d support on some chipsets (GM45, Sandy/
Ivy Bridge come to mind). You can look how it's done there. If you are
lucky, you only need to add 20~30 lines to your chipset's code.

If your chipset needs special initialization, it's most probably docu-
mented in the BIOS Writer's Guide (BWG) or BIOS Specification. Though,
you need an NDA with Intel to get these.

Nico

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Re: [coreboot] VT-d support

[ron minnich]

On Mon, Jun 5, 2017 at 9:58 AM Himanshu Chauhan 
wrote:

>
> I think its can’t just be disabled.
>

oh, really? Why do you think that? Have you looked at the relevant MSR and
what is the basis of your claim?

ron
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Re: [coreboot] VT-d support

[Himanshu Chauhan]

> On 05-Jun-2017, at 10:19 PM, ron minnich  wrote:
> 
> The reason I ask about what you need is that on chromebooks the main coreboot 
> support came down to 'don't disable anything’. 

I think its can’t just be disabled. Its just that kernel is not given any 
knowledge about its existence. This is what I want to know. The commercial 
BIOSes give an option of “enable VT-d” support. What do they do when this 
option is selected? Can this be implemented in Coreboot? This probably brings 
me to your next question of what is required. I would spend some time to figure 
that out.

> 
> The DMAR requirements are not met on all platforms. But even after boot you 
> can insert DMAR tables into kernels. 
> 
> So there is a key distinction between required support and desired support, 
> and I wonder if you could figure out what is required and let us know what it 
> is.
> 
> 

BTW, Do we have core boot tested on Intel’s Atom based C3xxx family SoCs?

> 
> On Mon, Jun 5, 2017 at 9:39 AM Zoran Stojsavljevic 
>  wrote:
> > what support does it need?
> 
> Intel Virtualization Technology for Directed I/O" (VT-d). VT-d is a 
> virtualized IOMMU, so by using HYP type 1 there should be a VT-d driver 
> supporting VT-d HW extension (?), as my best understanding is
> 
> The practical implications are Graphics and Network Connectivity in Guests. 
> DMA Remapping is the feature of VT-d.
> 
> Good net pointer to read: 
> https://unix.stackexchange.com/questions/34428/do-virtualbox-or-vmware-use-the-intel-vt-d-feature
> 
> > Is anybody working on this?
> 
> Don't think so... If anything is done, I guess, it is done by simplistic 
> implementation of the feature called: pass-through (so guest by its own 
> drivers is using directly platform devices' HW bypassing HYP1, my best guess).
> 
> Zoran
> On Mon, Jun 5, 2017 at 6:11 PM, ron minnich  wrote:
> 
> 
> On Mon, Jun 5, 2017 at 9:00 AM Himanshu Chauhan  
> wrote:
> Hi,
> 
> VT-d requires support from BIOS. Does coreboot support VT-d?
> 
> 
> 
> what support does it need?  
> 
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> https://mail.coreboot.org/mailman/listinfo/coreboot


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Re: [coreboot] VT-d support

[ron minnich]

The reason I ask about what you need is that on chromebooks the main
coreboot support came down to 'don't disable anything'.

The DMAR requirements are not met on all platforms. But even after boot you
can insert DMAR tables into kernels.

So there is a key distinction between required support and desired support,
and I wonder if you could figure out what is required and let us know what
it is.



On Mon, Jun 5, 2017 at 9:39 AM Zoran Stojsavljevic <
zoran.stojsavlje...@gmail.com> wrote:

> > what support does it need?
>
> Intel Virtualization Technology for Directed I/O" (VT-d). VT-d is a
> virtualized IOMMU, so by using HYP type 1 there should be a VT-d driver
> supporting VT-d HW extension (?), as my best understanding is
>
> The practical implications are Graphics and Network Connectivity in
> Guests. DMA Remapping is the feature of VT-d.
>
> Good net pointer to read:
> https://unix.stackexchange.com/questions/34428/do-virtualbox-or-vmware-use-the-intel-vt-d-feature
>
> > Is anybody working on this?
>
> Don't think so... If anything is done, I guess, it is done by simplistic
> implementation of the feature called: pass-through (so guest by its own
> drivers is using directly platform devices' HW bypassing HYP1, my best
> guess).
>
> Zoran
> On Mon, Jun 5, 2017 at 6:11 PM, ron minnich  wrote:
>
>>
>>
>> On Mon, Jun 5, 2017 at 9:00 AM Himanshu Chauhan 
>> wrote:
>>
>>> Hi,
>>>
>>> VT-d requires support from BIOS. Does coreboot support VT-d?
>>>
>>>
>>>
>> what support does it need?
>>
>> --
>> coreboot mailing list: coreboot@coreboot.org
>> https://mail.coreboot.org/mailman/listinfo/coreboot
>>
>
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Re: [coreboot] VT-d support

[Himanshu Chauhan]

> On 05-Jun-2017, at 10:02 PM, Zaolin  wrote:
> 
> You are asking for VT-d support. You are talking about Intel platforms ?

Yes. I am talking about intel platforms. All CPUs that have VT-d support need 
support from motherboards as well. So any setup with VT-d enabled CPU and a 
motherboards that assists it, is what I am talking about.

> 
> But for which specific platform you are asking for ? There are so many..
> 
> 
> Am 05.06.2017 um 10:24 schrieb Himanshu Chauhan:
>> 
>>> On 05-Jun-2017, at 9:41 PM, ron minnich  wrote:
>>> 
>>> 
>>> 
>>> On Mon, Jun 5, 2017 at 9:00 AM Himanshu Chauhan  
>>> wrote:
>>> Hi,
>>> 
>>> VT-d requires support from BIOS. Does coreboot support VT-d?
>>> 
>>> 
>>> 
>>> what support does it need?  
>> BIOS adds DMAR and other entries in the ACPI table. I am not quite sure how 
>> these entries are formed exactly though.
>> 
>> https://www.mjmwired.net/kernel/Documentation/Intel-IOMMU.txt
>> 
>> http://www.intel.com/content/dam/www/public/us/en/documents/product-specifications/vt-directed-io-spec.pdf
>> 
>> Is anybody working on this?
>> 
>> Regards
>> Himanshu
>> 
>> 
>> 
>> 
> 
> 
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> https://mail.coreboot.org/mailman/listinfo/coreboot


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Re: [coreboot] VT-d support

[Zoran Stojsavljevic]

> what support does it need?

Intel Virtualization Technology for Directed I/O" (VT-d). VT-d is a
virtualized IOMMU, so by using HYP type 1 there should be a VT-d driver
supporting VT-d HW extension (?), as my best understanding is

The practical implications are Graphics and Network Connectivity in Guests.
DMA Remapping is the feature of VT-d.

Good net pointer to read: https://unix.stackexchange.com/questions/34428/do-
virtualbox-or-vmware-use-the-intel-vt-d-feature

> Is anybody working on this?

Don't think so... If anything is done, I guess, it is done by simplistic
implementation of the feature called: pass-through (so guest by its own
drivers is using directly platform devices' HW bypassing HYP1, my best
guess).

Zoran

On Mon, Jun 5, 2017 at 6:11 PM, ron minnich  wrote:

>
>
> On Mon, Jun 5, 2017 at 9:00 AM Himanshu Chauhan 
> wrote:
>
>> Hi,
>>
>> VT-d requires support from BIOS. Does coreboot support VT-d?
>>
>>
>>
> what support does it need?
>
> --
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> https://mail.coreboot.org/mailman/listinfo/coreboot
>
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Re: [coreboot] VT-d support

[Zaolin]

You are asking for VT-d support. You are talking about Intel platforms ?

But for which specific platform you are asking for ? There are so many..


Am 05.06.2017 um 10:24 schrieb Himanshu Chauhan:
>
>> On 05-Jun-2017, at 9:41 PM, ron minnich  wrote:
>>
>>
>>
>> On Mon, Jun 5, 2017 at 9:00 AM Himanshu Chauhan  
>> wrote:
>> Hi,
>>
>> VT-d requires support from BIOS. Does coreboot support VT-d?
>>
>>
>>
>> what support does it need?  
> BIOS adds DMAR and other entries in the ACPI table. I am not quite sure how 
> these entries are formed exactly though.
>
> https://www.mjmwired.net/kernel/Documentation/Intel-IOMMU.txt
>
> http://www.intel.com/content/dam/www/public/us/en/documents/product-specifications/vt-directed-io-spec.pdf
>
> Is anybody working on this?
>
> Regards
> Himanshu
>
>
>
>




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Re: [coreboot] VT-d support

[Himanshu Chauhan]

> On 05-Jun-2017, at 9:41 PM, ron minnich  wrote:
> 
> 
> 
> On Mon, Jun 5, 2017 at 9:00 AM Himanshu Chauhan  
> wrote:
> Hi,
> 
> VT-d requires support from BIOS. Does coreboot support VT-d?
> 
> 
> 
> what support does it need?  

BIOS adds DMAR and other entries in the ACPI table. I am not quite sure how 
these entries are formed exactly though.

https://www.mjmwired.net/kernel/Documentation/Intel-IOMMU.txt

http://www.intel.com/content/dam/www/public/us/en/documents/product-specifications/vt-directed-io-spec.pdf

Is anybody working on this?

Regards
Himanshu




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Re: [coreboot] VT-d support

[ron minnich]

On Mon, Jun 5, 2017 at 9:00 AM Himanshu Chauhan 
wrote:

> Hi,
>
> VT-d requires support from BIOS. Does coreboot support VT-d?
>
>
>
what support does it need?
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