[Qemu-devel] Aspirant for AMD IOMMU emulation project for Outreachy

[Qemu-devel] Aspirant for AMD IOMMU emulation project for Outreachy

[Rita Sinha]

Hi Jan,

I am interested in participating in next round of Outreachy program
with AMD IOMMU emulation project.


I have worked on BIOS projects which includes coreboot SeaBios etc and
bootloaders like u-boot and grub. I have experience of working with
qemu and feel that this project is the right match for my skillset.
Kindly guide me how to go ahead with this.

Regards,
Rita Sinha

-- 
Regards,
Rita Sinha

Re: [Qemu-devel] Aspirant for AMD IOMMU emulation project for Outreachy

[Peter Maydell]

On 7 September 2015 at 22:31, Rita Sinha <rita.sinha89@gmail.com> wrote:
> Hi Jan,
>
> I am interested in participating in next round of Outreachy program
> with AMD IOMMU emulation project.
>
>
> I have worked on BIOS projects which includes coreboot SeaBios etc and
> bootloaders like u-boot and grub. I have experience of working with
> qemu and feel that this project is the right match for my skillset.
> Kindly guide me how to go ahead with this.

Hi Rita; I noticed you'd accidentally typo'd Jan's email address,
so I'm just following up with him cc'd to make sure he notices
this mail thread.

thanks
-- PMM

Re: [Qemu-devel] Aspirant for AMD IOMMU emulation project for Outreachy

[Jan Kiszka]

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[thanks for forwarding, Peter]

Hi Rita,

On 2015-09-08 10:11, Peter Maydell wrote:
> On 7 September 2015 at 22:31, Rita Sinha <rita.sinha89@gmail.com> wrote:
>> Hi Jan,
>>
>> I am interested in participating in next round of Outreachy program
>> with AMD IOMMU emulation project.
>>
>>
>> I have worked on BIOS projects which includes coreboot SeaBios etc and
>> bootloaders like u-boot and grub. I have experience of working with
>> qemu and feel that this project is the right match for my skillset.
>> Kindly guide me how to go ahead with this.

The particular AMD IOMMU project moved on since we listed it. I'm CC'ing
David, who is currently working on it and just recently posted related
patches, and Valentine who probably oversees the status better than I
(due to my lacking involvement recently). David, maybe you can briefly
comment on status and plans of your work.

For the Outreachy program, just like for GSoC, we need to find a good
topic that is sufficiently clear defined on program start and not worked
on in parallel during the runtime. There are still a number of open
topics in this area, e.g. around the older Intel IOMMU model (error
handling and reporting, interrupt remapping), or maybe we find something
different - depends on your interests and experiences. Do you have any
public references to your previous work?

Then I'd suggest to schedule an irc meeting to discuss your interests
and background a bit further and consider available options.

Jan


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Re: [Qemu-devel] Aspirant for AMD IOMMU emulation project for Outreachy

[David kiarie]

On Wed, Sep 9, 2015 at 12:35 AM, Jan Kiszka <jan.kiszka@web.de> wrote:
> [thanks for forwarding, Peter]
>
> Hi Rita,
>
> On 2015-09-08 10:11, Peter Maydell wrote:
>> On 7 September 2015 at 22:31, Rita Sinha <rita.sinha89@gmail.com> wrote:
>>> Hi Jan,
>>>
>>> I am interested in participating in next round of Outreachy program
>>> with AMD IOMMU emulation project.
>>>
>>>
>>> I have worked on BIOS projects which includes coreboot SeaBios etc and
>>> bootloaders like u-boot and grub. I have experience of working with
>>> qemu and feel that this project is the right match for my skillset.
>>> Kindly guide me how to go ahead with this.
>
> The particular AMD IOMMU project moved on since we listed it. I'm CC'ing
> David, who is currently working on it and just recently posted related
> patches, and Valentine who probably oversees the status better than I
> (due to my lacking involvement recently). David, maybe you can briefly
> comment on status and plans of your work.

Hi all,

Most recent work is here
http://lists.nongnu.org/archive/html/qemu-devel/2015-08/msg02759.html
. Most the code is Qemu device boilerplate(so there are a ton of
things to add but I wanted to have the existing work merged first).
The IOMMU just offers basic translation. From Valentine's previous
comments, I only have a few minor issues to fix in the code.

I obviously do other things alongside :-D this project but given some
time I could get the code merged and continue to add other features.

>
> For the Outreachy program, just like for GSoC, we need to find a good
> topic that is sufficiently clear defined on program start and not worked
> on in parallel during the runtime. There are still a number of open
> topics in this area, e.g. around the older Intel IOMMU model (error
> handling and reporting, interrupt remapping), or maybe we find something
> different - depends on your interests and experiences. Do you have any
> public references to your previous work?
>
> Then I'd suggest to schedule an irc meeting to discuss your interests
> and background a bit further and consider available options.
>
> Jan
>

Re: [Qemu-devel] Aspirant for AMD IOMMU emulation project for Outreachy

[Rita Sinha]

Hi Jan,

Please find my response inline.

>
> For the Outreachy program, just like for GSoC, we need to find a good
> topic that is sufficiently clear defined on program start and not worked
> on in parallel during the runtime. There are still a number of open
> topics in this area, e.g. around the older Intel IOMMU model (error
> handling and reporting, interrupt remapping), or maybe we find something
> different - depends on your interests and experiences. Do you have any
> public references to your previous work?
>

Most of my work has been for proprietary code repository and for
making contributions to open source projects is the reason why I am
applying to Outreachy.

I have worked on ACPI, qemu, coreboot, SeaBIOS, u-boot and linux
kernel and would love to work related areas.
Could you list down the open items for the same where I can select the
one which matches my skillset so that I can contribute more
efficiently to  this community.

> Then I'd suggest to schedule an irc meeting to discuss your interests
> and background a bit further and consider available options.
>

I guess that would be wonderful. Let me know when you are available on the IRC.


Regards,
Rita Sinha

Re: [Qemu-devel] Aspirant for AMD IOMMU emulation project for Outreachy

[Rita Sinha]

Hi David,

Please find my response inline.


>
> Hi all,
>
> Most recent work is here
> http://lists.nongnu.org/archive/html/qemu-devel/2015-08/msg02759.html
> . Most the code is Qemu device boilerplate(so there are a ton of
> things to add but I wanted to have the existing work merged first).
> The IOMMU just offers basic translation. From Valentine's previous
> comments, I only have a few minor issues to fix in the code.
>
> I obviously do other things alongside :-D this project but given some
> time I could get the code merged and continue to add other features.
>

Let me know if I can help in this effort which will help me get
started on this project.

Regards,
Rita Sinha

Re: [Qemu-devel] Aspirant for AMD IOMMU emulation project for Outreachy

[David kiarie]

On Wed, Sep 9, 2015 at 8:01 AM, Rita Sinha <rita.sinha89@gmail.com> wrote:
> Hi David,
>
> Please find my response inline.
>
>
>>
>> Hi all,
>>
>> Most recent work is here
>> http://lists.nongnu.org/archive/html/qemu-devel/2015-08/msg02759.html
>> . Most the code is Qemu device boilerplate(so there are a ton of
>> things to add but I wanted to have the existing work merged first).
>> The IOMMU just offers basic translation. From Valentine's previous
>> comments, I only have a few minor issues to fix in the code.
>>
>> I obviously do other things alongside :-D this project but given some
>> time I could get the code merged and continue to add other features.
>>
>
> Let me know if I can help in this effort which will help me get
> started on this project.

Hi Rita,

Most likely than not you'll work on the Intel IOMMU and I would
suggest, if you wish to get your feet dirty, just start right away
with the Intel IOMMU (In which case Jan could direct you better)
instead of the AMD one.

>
> Regards,
> Rita Sinha

Re: [Qemu-devel] Aspirant for AMD IOMMU emulation project for Outreachy

[Valentine Sinitsyn]

Hi all,

On 09.09.2015 09:23, David kiarie wrote:
> On Wed, Sep 9, 2015 at 12:35 AM, Jan Kiszka <jan.kiszka@web.de> wrote:
>> [thanks for forwarding, Peter]
>>
>> Hi Rita,
>>
>> On 2015-09-08 10:11, Peter Maydell wrote:
>>> On 7 September 2015 at 22:31, Rita Sinha <rita.sinha89@gmail.com> wrote:
>>>> Hi Jan,
>>>>
>>>> I am interested in participating in next round of Outreachy program
>>>> with AMD IOMMU emulation project.
>>>>
>>>>
>>>> I have worked on BIOS projects which includes coreboot SeaBios etc and
>>>> bootloaders like u-boot and grub. I have experience of working with
>>>> qemu and feel that this project is the right match for my skillset.
>>>> Kindly guide me how to go ahead with this.
>>
>> The particular AMD IOMMU project moved on since we listed it. I'm CC'ing
>> David, who is currently working on it and just recently posted related
>> patches, and Valentine who probably oversees the status better than I
>> (due to my lacking involvement recently). David, maybe you can briefly
>> comment on status and plans of your work.
>
> Hi all,
>
> Most recent work is here
> http://lists.nongnu.org/archive/html/qemu-devel/2015-08/msg02759.html
> . Most the code is Qemu device boilerplate(so there are a ton of
> things to add but I wanted to have the existing work merged first).
> The IOMMU just offers basic translation. From Valentine's previous
> comments, I only have a few minor issues to fix in the code.
This is a bit of off-topic here, but I'd argue they are minor. There are 
some inaccuracies in emulation, and IOMMU itself is rather 
feature-limited, just as you said. I doubt I'd be able to run current 
Jailhouse implementation on it, for instance, albeit I haven't tried. 
So, your patches are good start, but I feel there's a somewhat long way 
before they actually get merged.

So, in short: there are still tasks to be done in AMD IOMMU emulation 
project. I also feel it's possible to parallelize them so David and Rita 
can continue without stepping at each other toe, if the program permits it.

> I obviously do other things alongside :-D this project but given some
> time I could get the code merged and continue to add other features.
>
>>
>> For the Outreachy program, just like for GSoC, we need to find a good
>> topic that is sufficiently clear defined on program start and not worked
>> on in parallel during the runtime. There are still a number of open
>> topics in this area, e.g. around the older Intel IOMMU model (error
>> handling and reporting, interrupt remapping), or maybe we find something
>> different - depends on your interests and experiences. Do you have any
>> public references to your previous work?
>>
>> Then I'd suggest to schedule an irc meeting to discuss your interests
>> and background a bit further and consider available options.
>>
>> Jan
>>

Regards,
Valentine

Re: [Qemu-devel] Aspirant for AMD IOMMU emulation project for Outreachy

[David kiarie]

On Wed, Sep 9, 2015 at 9:47 AM, Valentine Sinitsyn
<valentine.sinitsyn@gmail.com> wrote:
> Hi all,
>
>
> On 09.09.2015 09:23, David kiarie wrote:
>>
>> On Wed, Sep 9, 2015 at 12:35 AM, Jan Kiszka <jan.kiszka@web.de> wrote:
>>>
>>> [thanks for forwarding, Peter]
>>>
>>> Hi Rita,
>>>
>>> On 2015-09-08 10:11, Peter Maydell wrote:
>>>>
>>>> On 7 September 2015 at 22:31, Rita Sinha <rita.sinha89@gmail.com> wrote:
>>>>>
>>>>> Hi Jan,
>>>>>
>>>>> I am interested in participating in next round of Outreachy program
>>>>> with AMD IOMMU emulation project.
>>>>>
>>>>>
>>>>> I have worked on BIOS projects which includes coreboot SeaBios etc and
>>>>> bootloaders like u-boot and grub. I have experience of working with
>>>>> qemu and feel that this project is the right match for my skillset.
>>>>> Kindly guide me how to go ahead with this.
>>>
>>>
>>> The particular AMD IOMMU project moved on since we listed it. I'm CC'ing
>>> David, who is currently working on it and just recently posted related
>>> patches, and Valentine who probably oversees the status better than I
>>> (due to my lacking involvement recently). David, maybe you can briefly
>>> comment on status and plans of your work.
>>
>>
>> Hi all,
>>
>> Most recent work is here
>> http://lists.nongnu.org/archive/html/qemu-devel/2015-08/msg02759.html
>> . Most the code is Qemu device boilerplate(so there are a ton of
>> things to add but I wanted to have the existing work merged first).
>> The IOMMU just offers basic translation. From Valentine's previous
>> comments, I only have a few minor issues to fix in the code.
>
> This is a bit of off-topic here, but I'd argue they are minor. There are
> some inaccuracies in emulation, and IOMMU itself is rather feature-limited,
> just as you said. I doubt I'd be able to run current Jailhouse
> implementation on it, for instance, albeit I haven't tried. So, your patches
> are good start, but I feel there's a somewhat long way before they actually
> get merged.

Yep, that is possible. For instance, you were insisting on 'cache'
implemention ;) which IMHO, is optional but could be a good project
start.

>
> So, in short: there are still tasks to be done in AMD IOMMU emulation
> project. I also feel it's possible to parallelize them so David and Rita can
> continue without stepping at each other toe, if the program permits it.
>
>> I obviously do other things alongside :-D this project but given some
>> time I could get the code merged and continue to add other features.
>>
>>>
>>> For the Outreachy program, just like for GSoC, we need to find a good
>>> topic that is sufficiently clear defined on program start and not worked
>>> on in parallel during the runtime. There are still a number of open
>>> topics in this area, e.g. around the older Intel IOMMU model (error
>>> handling and reporting, interrupt remapping), or maybe we find something
>>> different - depends on your interests and experiences. Do you have any
>>> public references to your previous work?
>>>
>>> Then I'd suggest to schedule an irc meeting to discuss your interests
>>> and background a bit further and consider available options.
>>>
>>> Jan
>>>
>
> Regards,
> Valentine

Re: [Qemu-devel] Aspirant for AMD IOMMU emulation project for Outreachy

[Valentine Sinitsyn]

On 09.09.2015 11:54, David kiarie wrote:
...snip...
>>> Most recent work is here
>>> http://lists.nongnu.org/archive/html/qemu-devel/2015-08/msg02759.html
>>> . Most the code is Qemu device boilerplate(so there are a ton of
>>> things to add but I wanted to have the existing work merged first).
>>> The IOMMU just offers basic translation. From Valentine's previous
>>> comments, I only have a few minor issues to fix in the code.
>>
>> This is a bit of off-topic here, but I'd argue they are minor. There are
>> some inaccuracies in emulation, and IOMMU itself is rather feature-limited,
>> just as you said. I doubt I'd be able to run current Jailhouse
>> implementation on it, for instance, albeit I haven't tried. So, your patches
>> are good start, but I feel there's a somewhat long way before they actually
>> get merged.
>
> Yep, that is possible. For instance, you were insisting on 'cache'
> implemention ;) which IMHO, is optional but could be a good project
> start.
The thing that worried me most is how you handle invalid Device Table 
entries, and that most bits in control/status registers are actually 
no-op. And I don't insist on cache implementation, just make sure there 
is a way to invalidate the configuration. Maybe I overlooked something 
and you already do it?

Let's discuss it not in this thread but where your patch is.

>
>>
>> So, in short: there are still tasks to be done in AMD IOMMU emulation
>> project. I also feel it's possible to parallelize them so David and Rita can
>> continue without stepping at each other toe, if the program permits it.
>>
>>> I obviously do other things alongside :-D this project but given some
>>> time I could get the code merged and continue to add other features.
>>>
>>>>
>>>> For the Outreachy program, just like for GSoC, we need to find a good
>>>> topic that is sufficiently clear defined on program start and not worked
>>>> on in parallel during the runtime. There are still a number of open
>>>> topics in this area, e.g. around the older Intel IOMMU model (error
>>>> handling and reporting, interrupt remapping), or maybe we find something
>>>> different - depends on your interests and experiences. Do you have any
>>>> public references to your previous work?
>>>>
>>>> Then I'd suggest to schedule an irc meeting to discuss your interests
>>>> and background a bit further and consider available options.
>>>>
>>>> Jan
>>>>
>>
>> Regards,
>> Valentine

Valentine

Re: [Qemu-devel] Aspirant for AMD IOMMU emulation project for Outreachy

[Rita Sinha]

Hi Jan,

>
> Most likely than not you'll work on the Intel IOMMU and I would
> suggest, if you wish to get your feet dirty, just start right away
> with the Intel IOMMU (In which case Jan could direct you better)
> instead of the AMD one.
>

As suggested by David, I would request you to guide me as to how to
get started with Intel IOMMU.


Regards,
Rita Sinha

Re: [Qemu-devel] Aspirant for AMD IOMMU emulation project for Outreachy

[Jan Kiszka]

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Hi Rita,

[CC'ing Andrew due to overlap with split irqchip topic]

On 2015-09-09 19:41, Rita Sinha wrote:
> Hi Jan,
> 
>>
>> Most likely than not you'll work on the Intel IOMMU and I would
>> suggest, if you wish to get your feet dirty, just start right away
>> with the Intel IOMMU (In which case Jan could direct you better)
>> instead of the AMD one.
>>
> 
> As suggested by David, I would request you to guide me as to how to
> get started with Intel IOMMU.
> 

You can find the basic problem description and some links here:

http://wiki.qemu.org/Google_Summer_of_Code_2015#VT-d_interrupt_emulation_with_KVM_support

Who much do you know about IOMMUs and interrupt remapping in general?
The spec may provide a certain introduction to the topic, but it also
quickly dives into details. Let me know where you see gaps to build up a
better understanding of the topic.

Implementation-wise, you could start off with the existing interrupt
remapping patches and look into the missing error reporting for IR on
that basis. I've just rebased and pushed a new version. Error reporting
is currently done in form of plain printf. The correct behaviour is
described in the spec. Feel free to nag me with questions on how things
work around interrupt remapping in general and its QEMU integration in
particular.

The goal is to get this upstream eventually. So the current design needs
to be prepared for submission, reviewed by subsystem maintainer, and
then possibly reworked based on their feedback. We will also need some
command line switch (machine property, like iommu=on) to control the
availability of IR because the original Q35 chipset didn't include this
feature.

But there is also the aim to integrate it with KVM support, and that's
why I'm CC'ing Andrew. At Google, they are currently working on QEMU
patches for their split KVM irqchip model. This will push the IOAPIC
into QEMU hands, even when KVM in-kernel APIC acceleration is used. And
that will allow IR to be installed easily, without any KVM kernel-side
changes.

Andrew, what is the status of your QEMU patches? Are there chances to
preview them in order to asses if and how much integration work is
needed for interrupt remapping?

Rita, you probably noticed that this is no beginner's task, both
regarding the hardware background as well as the QEMU subsystems. You
have worked with several low-level software components before and have
some QEMU experience, so this topic could be a good match for you.
Still, if you have doubts after looking into details, let me know so
that we can discuss them.

Best regards,
Jan


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Re: [Qemu-devel] Aspirant for AMD IOMMU emulation project for Outreachy

[Jan Kiszka]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 2015-09-11 08:50, Jan Kiszka wrote:
> Hi Rita,
> 
> [CC'ing Andrew due to overlap with split irqchip topic]
> 
> On 2015-09-09 19:41, Rita Sinha wrote:
>> Hi Jan,
>> 
>>> 
>>> Most likely than not you'll work on the Intel IOMMU and I would
>>> suggest, if you wish to get your feet dirty, just start right
>>> away with the Intel IOMMU (In which case Jan could direct you
>>> better) instead of the AMD one.
>>> 
>> 
>> As suggested by David, I would request you to guide me as to how 
>> to get started with Intel IOMMU.
>> 
> 
> You can find the basic problem description and some links here:
> 
> http://wiki.qemu.org/Google_Summer_of_Code_2015#VT-d_interrupt_emulation_with_KVM_support
>
>
> 
Who much do you know about IOMMUs and interrupt remapping in
> general? The spec may provide a certain introduction to the topic, 
> but it also quickly dives into details. Let me know where you see 
> gaps to build up a better understanding of the topic.
> 
> Implementation-wise, you could start off with the existing 
> interrupt remapping patches and look into the missing error 
> reporting for IR on that basis. I've just rebased and pushed a new 
> version. Error reporting

Oh, another way to approach the topic could be developing unit tests
for the IOMMU. However, I'm not the expert on the related framework
but we'll find one if you like to look into this. You find such tests
in the, well, tests/ subdirectory, for various QEMU aspects in fact.

Jan

> is currently done in form of plain printf. The correct behaviour is
> described in the spec. Feel free to nag me with questions on how 
> things work around interrupt remapping in general and its QEMU 
> integration in particular.
> 
> The goal is to get this upstream eventually. So the current design 
> needs to be prepared for submission, reviewed by subsystem 
> maintainer, and then possibly reworked based on their feedback. We 
> will also need some command line switch (machine property, like 
> iommu=on) to control the availability of IR because the original 
> Q35 chipset didn't include this feature.
> 
> But there is also the aim to integrate it with KVM support, and 
> that's why I'm CC'ing Andrew. At Google, they are currently
> working on QEMU patches for their split KVM irqchip model. This
> will push the IOAPIC into QEMU hands, even when KVM in-kernel APIC 
> acceleration is used. And that will allow IR to be installed 
> easily, without any KVM kernel-side changes.
> 
> Andrew, what is the status of your QEMU patches? Are there chances 
> to preview them in order to asses if and how much integration work 
> is needed for interrupt remapping?
> 
> Rita, you probably noticed that this is no beginner's task, both 
> regarding the hardware background as well as the QEMU subsystems. 
> You have worked with several low-level software components before 
> and have some QEMU experience, so this topic could be a good match 
> for you. Still, if you have doubts after looking into details, let 
> me know so that we can discuss them.
> 
> Best regards, Jan
> 

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