From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Jonas Pfefferle <pepperjo@japf.ch>,
Thomas Monjalon <thomas@monjalon.net>
Cc: "Burakov, Anatoly" <anatoly.burakov@intel.com>, dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v2] vfio: noiommu check error handling
Date: Wed, 17 Jan 2018 09:55:37 +0100 [thread overview]
Message-ID: <ac2497d4-6c31-0440-5b71-c70bd3a5066d@redhat.com> (raw)
In-Reply-To: <web-42370564@switchplus-mail.ch>
On 01/17/2018 09:48 AM, Jonas Pfefferle wrote:
>
> On Tue, 16 Jan 2018 18:01:32 +0100
> Maxime Coquelin <maxime.coquelin@redhat.com> wrote:
>> Hi Jonas,
>>
>> On 01/16/2018 05:08 PM, Jonas Pfefferle wrote:
>>>
>>> On Mon, 15 Jan 2018 17:11:58 +0100
>>> Thomas Monjalon <thomas@monjalon.net> wrote:
>>>> 15/01/2018 13:22, Jonas Pfefferle:
>>>>>
>>>>> On Sat, 13 Jan 2018 23:49:30 +0100
>>>>> Thomas Monjalon <thomas@monjalon.net> wrote:
>>>>> > 13/01/2018 13:15, Burakov, Anatoly:
>>>>> >> On 11-Jan-18 11:45 PM, Thomas Monjalon wrote:
>>>>> >> > 07/11/2017 10:50, Jonas Pfefferle1:
>>>>> >> >>> Is there something urgent for 17.11?
>>>>> >> >>> Or can it be refined in 18.02?
>>>>> >> >>
>>>>> >> >> Nothing urgent. We can refine this for 18.02.
>>>>> >> >>
>>>>> >> >>> Anatoly, any thought?
>>>>> >> > >> > Anatoly, Jonas, how do you want to proceed with this patch?
>>>>> >> > >> >> I don't see anything to be refined here, it's a simple
>>>>> bug fix - >>code >> assumes noiommu mode support is always
>>>>> available, when it might not >>be >> the case on older kernels.
>>>>> > > As a bug fix, the title must start with "fix" and a tag "Fixes:"
>>>>> > must be added to help with backport.
>>>>> > At the same time, the explanation of the bug must be added in
>>>>> > the commit log please.
>>>>> > > Thanks
>>>>>
>>>>> It's not really a bug fix since it does not change the semantic of
>>>>> the function but just adds nicer error handling.
>>>>> Regarding redefining the code: What I don't like is the special
>>>>> cases we have to check for when using the sPAPR iommu because it
>>>>> does not support VA mappings yet. I think we should decide which
>>>>> iova mode to use based on the iommu types available, i.e. each
>>>>> iommu type should report which iova type it supports. Thoughts?
>>>>
>>>> Have you looked at what Maxime did?
>>>> https://dpdk.org/dev/patchwork/patch/33650/
>>>>
>>>> How does it affect this patch?
>>>>
>>>>
>>>
>>> IMO it has the same problem. We shouldn't add more exception cases in
>>> drivers/bus/pci/linux/pci.c but instead keep all the information
>>> about what an IOMMU can do in lib/librte_eal/linuxapp/eal/eal_vfio.c
>>
>> I agree adding an exception in drivers/bus/pci/linux/pci.c isn't great,
>> but we need first to fix a regression introduced in v17.11 LTS, and
>> IMHO, we cannot do a big rework as the fix is to be backported.
>>
>> Once fixed, I agree we should work on a refactoring. I don't know if
>> eal_vfio is the right place though, as in my case for example I cannot
>> get the information needed through vfio ioctl().
>>
>> Out of curiosity, what prevents sPAPR to use VA mode for now?
>>
>> Maxime
>
> Sounds good to me.
>
> The current sPAPR Linux driver cannot use virtual addresses because the
> DMA window size is restricted to RAM size and always starts at 0. This
> is not a hardware restriction and we are working on allowing to create
> arbitrary size windows.
Thanks for the clarification, is the DMA window size information
accessible from user-space, so that we can enable VA mode or not
depending on its value?
Maxime
> Jonas
>
>
>
next prev parent reply other threads:[~2018-01-17 8:55 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-31 15:59 Jonas Pfefferle
2017-11-06 20:25 ` Thomas Monjalon
2017-11-07 9:05 ` Jonas Pfefferle1
2017-11-07 9:40 ` Thomas Monjalon
2017-11-07 9:50 ` Jonas Pfefferle1
2018-01-11 23:45 ` Thomas Monjalon
2018-01-13 12:15 ` Burakov, Anatoly
2018-01-13 22:49 ` Thomas Monjalon
2018-01-15 12:22 ` Jonas Pfefferle
2018-01-15 16:11 ` Thomas Monjalon
2018-01-16 16:08 ` Jonas Pfefferle
2018-01-16 17:01 ` Maxime Coquelin
2018-01-17 8:48 ` Jonas Pfefferle
2018-01-17 8:55 ` Maxime Coquelin [this message]
2018-01-17 10:34 ` Jonas Pfefferle
2018-01-16 10:07 ` Burakov, Anatoly
2018-01-16 16:09 ` Jonas Pfefferle
2018-01-13 12:05 ` Burakov, Anatoly
2018-01-19 17:37 ` Maxime Coquelin
2018-01-20 14:48 ` Thomas Monjalon
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