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Message-ID: <20221206153811.GB2266@lst.de>
Date: Tue, 6 Dec 2022 16:38:11 +0100
From: Christoph Hellwig <hch@....de>
To: Jason Gunthorpe <jgg@...pe.ca>
Cc: Christoph Hellwig <hch@....de>, Lei Rao <lei.rao@...el.com>,
kbusch@...nel.org, axboe@...com, kch@...dia.com, sagi@...mberg.me,
alex.williamson@...hat.com, cohuck@...hat.com, yishaih@...dia.com,
shameerali.kolothum.thodi@...wei.com, kevin.tian@...el.com,
mjrosato@...ux.ibm.com, linux-kernel@...r.kernel.org,
linux-nvme@...ts.infradead.org, kvm@...r.kernel.org,
eddie.dong@...el.com, yadong.li@...el.com, yi.l.liu@...el.com,
Konrad.wilk@...cle.com, stephen@...eticom.com, hang.yuan@...el.com
Subject: Re: [RFC PATCH 1/5] nvme-pci: add function nvme_submit_vf_cmd to
issue admin commands for VF driver.
On Tue, Dec 06, 2022 at 11:22:33AM -0400, Jason Gunthorpe wrote:
> > controlled functions (which could very well be, and in some designs
> > are, additional PFs and not VFs) by controlling function.
>
> In principle PF vs VF doesn't matter much - the question is really TLP
> labeling. If the spec says RID A is the controlling RID and RID B is
> the guest RID, then it doesn't matter if they have a PF/VF
> relationship or PF/PF relationship.
Yes. Or in fact if you use PASIDs inside a single function.
> We have locking issues in Linux SW connecting different SW drivers for
> things that are not a PF/VF relationship, but perhaps that can be
> solved.
And I think the only reasonable answer is that the entire workflow
must be 100% managed from the controlling function, and the controlled
function is just around for a ride, with the controlling function
enabling/disabling it as needed without ever interacting with software
that directly deals with the controlled function.
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