[PATCH 2/2] NVMe: Implement PCI-e reset notification callback

[Mayes, Barrett N]

Section 8.5 of the NVMe 1.1 spec contains the following:  "While the details associated with implementing a controller that supports SR-IOV are outside the scope of this specification, such a controller shall implement fully compliant NVM Express Virtual Functions (VFs). This ensures that the same host software developed for non-virtualized environments is capable of running unmodified within an SI. No such requirement exists for the Physical Function (PF)."

If a VF is a fully NVMe compliant device then it must at least act like it implements NVMe subsystem reset.  How the SR-IOV-capable controller actually implements this is left up to the vendor.  But the spec does not require that a reset of one VF initiate a reset of other VF.

-----Original Message-----
From: Linux-nvme [mailto:linux-nvme-bounces at lists.infradead.org] On Behalf Of Learner Study
Sent: Monday, April 21, 2014 8:34 PM
To: Busch, Keith
Cc: bhelgaas at google.com; linux-pci at vger.kernel.org; linux-nvme
Subject: Re: [PATCH 2/2] NVMe: Implement PCI-e reset notification callback

Per the spec, "When an NVM Subsystem Reset occurs, the entire NVM subsystem is reset"....so all VFs would get impacted, if a VF does a Reset. So, I think Reset kind of control should be in PF mode only.

On Mon, Apr 21, 2014 at 7:45 PM, Learner <learner.study at gmail.com> wrote:
> But Won't resetting from a VF impact functionality of other VFs?
>
> On Apr 21, 2014, at 6:57 PM, Keith Busch <keith.busch at intel.com> wrote:
>
>> On Mon, 21 Apr 2014, Learner Study wrote:
>>> Hi Keith,
>>>
>>> I think NVMe Reset should apply to PF mode driver only, and not to 
>>> VF mode driver.
>>> Is that understanding correct? Does the NVMe driver know which mode 
>>> its running in?
>>
>> Oh, this driver doesn't enable SR-IOV and has no PF/VF awareness. 
>> Shame on us, I'll add it to my list unless someone beats me to it.
>>
>> Still, I think we'd like to be able to reset a VF if only because it 
>> gets the queues back to a pristine state. A VF reset should not 
>> affect any of the other functions.

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