linux-kernel - Re: [PATCH v5 2/2] s390: virtio: PV needs VIRTIO I/O device protection

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Date:   Thu, 9 Jul 2020 17:06:15 +0200
From:   Halil Pasic <pasic@...ux.ibm.com>
To:     Pierre Morel <pmorel@...ux.ibm.com>
Cc:     Cornelia Huck <cohuck@...hat.com>, linux-kernel@...r.kernel.org,
        borntraeger@...ibm.com, frankja@...ux.ibm.com, mst@...hat.com,
        jasowang@...hat.com, kvm@...r.kernel.org,
        linux-s390@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, thomas.lendacky@....com,
        david@...son.dropbear.id.au, linuxram@...ibm.com,
        heiko.carstens@...ibm.com, gor@...ux.ibm.com
Subject: Re: [PATCH v5 2/2] s390: virtio: PV needs VIRTIO I/O device
 protection

On Thu, 9 Jul 2020 16:51:04 +0200
Pierre Morel <pmorel@...ux.ibm.com> wrote:

> 
> 
> On 2020-07-09 16:47, Halil Pasic wrote:
> > On Thu, 9 Jul 2020 12:51:58 +0200
> > Pierre Morel <pmorel@...ux.ibm.com> wrote:
> > 
> >>>> +int arch_validate_virtio_features(struct virtio_device *dev)
> >>>> +{
> >>>> +	if (!is_prot_virt_guest())
> >>>> +		return 0;
> >>>> +
> >>>> +	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
> >>>> +		dev_warn(&dev->dev, "device must provide VIRTIO_F_VERSION_1\n");
> >>>
> >>> I'd probably use "legacy virtio not supported with protected
> >>> virtualization".
> >>>    
> >>>> +		return -ENODEV;
> >>>> +	}
> >>>> +
> >>>> +	if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) {
> >>>> +		dev_warn(&dev->dev,
> >>>> +			 "device must provide VIRTIO_F_IOMMU_PLATFORM\n");
> >>>
> >>> "support for limited memory access required for protected
> >>> virtualization"
> >>>
> >>> ?
> >>>
> >>> Mentioning the feature flag is shorter in both cases, though.
> >>
> >> And I think easier to look for in case of debugging purpose.
> >> I change it if there is more demands.
> > 
> > Not all our end users are kernel and/or qemu developers. I find the
> > messages from v4 less technical, more informative, and way better.
> > 
> > Regards,
> > Halil
> > 
> 
> Can you please tell me the messages you are speaking of, because for me 
> the warning's messages are exactly the same in v4 and v5!?
> 
> I checked many times, but may be I still missed something.
> 

Sorry, my bad. My brain is over-generating. The messages where discussed
at v3 and Connie made a very similar proposal to the one above which I
seconded (for reference look at Message-ID:
<833c71f2-0057-896a-5e21-2c6263834402@...ux.ibm.com>). I was under the
impression that it got implemented in v4, but it was not. That's why I
ended up talking bs.

Regards,
Halil