Re: [Xen-devel] [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute

[George Dunlap <George.Dunlap@xxxxxxxxxx>]

> On Jan 31, 2020, at 3:33 PM, Wei Liu <wl@xxxxxxx> wrote:
> 
> On Fri, Jan 17, 2020 at 02:13:04PM -0500, Rich Persaud wrote:
>> On Aug 26, 2019, at 17:08, Pasi Kärkkäinen <pasik@xxxxxx> wrote:
>>> Hi,
>>> 
>>>> On Mon, Oct 08, 2018 at 10:32:45AM -0400, Boris Ostrovsky wrote:
>>>>> On 10/3/18 11:51 AM, Pasi Kärkkäinen wrote:
>>>>> On Wed, Sep 19, 2018 at 11:05:26AM +0200, Roger Pau Monné wrote:
>>>>>> On Tue, Sep 18, 2018 at 02:09:53PM -0400, Boris Ostrovsky wrote:
>>>>>>> On 9/18/18 5:32 AM, George Dunlap wrote:
>>>>>>>>> On Sep 18, 2018, at 8:15 AM, Pasi Kärkkäinen <pasik@xxxxxx> wrote:
>>>>>>>>> Hi,
>>>>>>>>> On Mon, Sep 17, 2018 at 02:06:02PM -0400, Boris Ostrovsky wrote:
>>>>>>>>>> What about the toolstack changes? Have they been accepted? I vaguely
>>>>>>>>>> recall there was a discussion about those changes but don't remember 
>>>>>>>>>> how
>>>>>>>>>> it ended.
>>>>>>>>> I don't think toolstack/libxl patch has been applied yet either.
>>>>>>>>> "[PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS attribute":
>>>>>>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
>>>>>>>>> "[PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' SysFS 
>>>>>>>>> attribute":
>>>>>>>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html
>>>>>>> Will this patch work for *BSD? Roger?
>>>>>> At least FreeBSD don't support pci-passthrough, so none of this works
>>>>>> ATM. There's no sysfs on BSD, so much of what's in libxl_pci.c will
>>>>>> have to be moved to libxl_linux.c when BSD support is added.
>>>>> Ok. That sounds like it's OK for the initial pci 'reset' implementation 
>>>>> in xl/libxl to be linux-only..
>>>> 
>>>> Are these two patches still needed? ISTR they were  written originally
>>>> to deal with guest trying to use device that was previously assigned to
>>>> another guest. But pcistub_put_pci_dev() calls
>>>> __pci_reset_function_locked() which first tries FLR, and it looks like
>>>> it was added relatively recently.
>>> 
>>> Replying to an old thread.. I only now realized I forgot to reply to this 
>>> message earlier.
>>> 
>>> afaik these patches are still needed. Håkon (CC'd) wrote to me in private 
>>> that
>>> he gets a (dom0) Linux kernel crash if he doesn't have these patches 
>>> applied.
>>> 
>>> 
>>> Here are the links to both the linux kernel and libxl patches:
>>> 
>>> 
>>> "[Xen-devel] [PATCH V3 0/2] Xen/PCIback: PCI reset using 'reset' SysFS 
>>> attribute":
>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00659.html
>>> 
>>> [Note that PATCH V3 1/2 "Drivers/PCI: Export pcie_has_flr() interface" is 
>>> already applied in upstream linux kernel, so it's not needed anymore]
>>> 
>>> "[Xen-devel] [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset 
>>> with 'reset' SysFS attribute":
>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00661.html
>>> 
>>> 
>>> "[Xen-devel] [PATCH V1 0/1] Xen/Tools: PCI reset using 'reset' SysFS 
>>> attribute":
>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00664.html
>>> 
>>> "[Xen-devel] [PATCH V1 1/1] Xen/libxl: Perform PCI reset using 'reset' 
>>> SysFS attribute":
>>> https://lists.xen.org/archives/html/xen-devel/2017-12/msg00663.html
>> 
>> [dropping Linux mailing lists]
>> 
>> What is required to get the Xen patches merged?  Rebasing against Xen
>> master?  OpenXT has been carrying a similar patch for many years and
>> we would like to move to an upstream implementation.  Xen users of PCI
>> passthrough would benefit from more reliable device reset.
> 
> Rebase and resend?
> 
> Skimming that thread I think the major concern was backward
> compatibility. That seemed to have been addressed.
> 
> Unfortunately I don't have the time to dig into Linux to see if the
> claim there is true or not.
> 
> It would be helpful to write a concise paragraph to say why backward
> compatibility is not required.

Just going through my old “make sure something happens with this” mails.  Did 
anything ever happen with this?  Who has the ball here / who is this stuck on?

 -George