[vbox-dev] ICH9 MSI handling

Ananth Pallapothu apallapothu at gmail.com
Tue Jan 5 19:08:06 UTC 2016


Attached Patch log file along with the source code, requesting to submit
under MIT License. Let me know if I missed anything.

Ananth

On Wed, Dec 30, 2015 at 2:52 PM, Michal Necasek <michal.necasek at oracle.com>
wrote:

>
>  Please take a look at this:
> https://www.virtualbox.org/wiki/Contributor_information
>
>  For a small patch, I highly recommend submitting it under the MIT
> license. Basically you post the patch on this list and state that it's
> provided under the MIT license. We'll take a look at it, possibly modify
> it, and apply (if we're happy with it).
>
>  A patch has higher chance of being accepted when it follows the
> VirtualBox coding standards and is reasonably well designed. For example
> requiring the user to directly modify the PCI config registers sounds like
> something that should be avoided for MSIs. But let's see the patch first.
>
>       Regards,
>          Michal
>
> ----- Original Message -----
> From: apallapothu at gmail.com
> To: michal.necasek at oracle.com
> Cc: vbox-dev at virtualbox.org
> Sent: Wednesday, December 30, 2015 12:30:02 AM GMT +01:00 Amsterdam /
> Berlin / Bern / Rome / Stockholm / Vienna
> Subject: Re: [vbox-dev] ICH9 MSI handling
>
> 2 things that I do 1) Directly write to control config register for 64 bit
> using *setbyte or *setword function calls 2) I set "pMsiReg->fMsi64bit"
> during MSI registration.
>
> I presume changes might help other users, so would be glad to submit
> changes. Never submitted patches before, what is the process to do so ?
>
> Ananth
>
> On Tue, Dec 29, 2015 at 5:36 AM, Michal Necasek <michal.necasek at oracle.com
> > wrote:
>
>>
>>  I can't say much without seeing exactly what you changed. But just two
>> questions:
>>
>>  - Do you call pciDevSetMsi64Capable() anywhere? Perhaps MsiInit() should
>> be doing that.
>>  - Did you set pMsiReg->fMsi64bit before registering the MSI capability?
>>
>>  It is entirely possible that the 64-bit MSI support is not as good as it
>> could be since VirtualBox does not ship with any devices which use that.
>>
>>  Are you going to submit patches for VirtualBox or are you happy with
>> maintaining local changes?
>>
>>
>>      - Michal
>>
>> On 12/29/2015 5:44 AM, Ananth Pallapothu wrote:
>>
>>> Hi Michal,
>>>
>>>     I was able to get my device working for MSI Interrupts Non-masking.
>>>
>>>     Problem was 3 folded.
>>>     1) A) Added new msiMaskEnabled function to do appropriate checkings
>>>         B) Existing check conditions inside MsiNotify are specifically
>>> isolated incase of Non-Masking.
>>>     2) I invoke exclusive register write access to MSI control at the
>>> very end of my constructor (after MSI registration call)
>>>     3) msiIs64Bit never returned functionally appropriate/true value. So
>>> I modified this function to return appropriate value by reading control
>>> config & 0x80
>>>
>>> Thanks.
>>>
>>>
>>>
>>>
>>> On Mon, Dec 28, 2015 at 4:50 AM, Michal Necasek
>>> <michal.necasek at oracle.com <mailto:michal.necasek at oracle.com>> wrote:
>>>
>>>
>>>       Hmm, that doesn't make sense to me. The mask bits do not overlap
>>>     anything else. I'm looking at figure 6-9 on page 233 of the PCI 3.0
>>>     specification.
>>>
>>>       The code in MsiCommon.cpp is clear enough. Are you failing to set
>>>     the fMsi64bit flag when registering the MSI capability?
>>>
>>>       You probably also noticed that MsiInit() always sets the
>>>     BOX_PCI_MSI_FLAGS_MASKBIT and there is currently no way to register
>>>     an emulated device without MSI per-vector masking. That should not
>>>     cause trouble since guest software does not have to use masking.
>>>
>>>           - Michal
>>>
>>>
>>>     ----- Original Message -----
>>>     From: apallapothu at gmail.com <mailto:apallapothu at gmail.com>
>>>     To: vbox-dev at virtualbox.org <mailto:vbox-dev at virtualbox.org>
>>>     Sent: Monday, December 21, 2015 5:16:15 AM GMT +01:00 Amsterdam /
>>>     Berlin / Bern / Rome / Stockholm / Vienna
>>>     Subject: [vbox-dev] ICH9 MSI handling
>>>
>>>     Hello Developers,
>>>
>>>            I am experimenting on ICH9 with a pluggable device. Reason
>>>     for using ICH9 is MSI support.
>>>     Following through AHCI, HPET device I see that code is aligned for
>>>     specific mode of MSI configuration, "Per-Vector Masking Capable".
>>>
>>>            MsiNotify function reads Mask Bits, Pending Bits without
>>>     conditionally checking whether device is Per-Vector Masking Capable.
>>>     So, by default code thinks offset 0xC reg as mask data where infact
>>>     it is MSI data with Interrupt Vector ID incase of masking disabled.
>>>     iVector value seems to be confusing too.
>>>
>>>           My particular device needs to be configured for 64 bit MSI
>>>     address capable and Mask disabled, so, MSI_MSG_CNTL @ MSI capability
>>>     offset 0x02 = 0x0081
>>>
>>>          Can someone please suggest, recommend changes to handle this
>>>     mode of MSI operation ?
>>>
>>>     Thanks.
>>>
>>>
>>>
>>
>
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