Re: [RFC PATCH] virt: tdx-guest: Remove quote generation via ioctl

["Daniel P. Berrangé" <berrange@redhat.com>]

On Tue, Jan 23, 2024 at 11:06:01AM -0800, Dan Williams wrote:
> Nikolay Borisov wrote:
> > 
> > 
> > On 23.01.24 г. 19:51 ч., Kuppuswamy Sathyanarayanan wrote:
> > > 
> > > On 1/23/24 8:07 AM, Nikolay Borisov wrote:
> > >> When this driver got merged initially there was no widely agreed upon
> > >> interface how the quote generation interface will work so having an
> > >> ioctl made sense. However, there's now a vendor-neutral interface via
> > >> configfs. Just remove the old ioctl interface and leave only the the
> > >> configfs one.
> > >>
> > >> Signed-off-by: Nikolay Borisov <nik.borisov@suse.com>
> > >> ---
> > > 
> > > This ABI allows the user to get the raw report which is further used
> > > for Quote generation via vsock. AFAIK, some vendors (TDX users) and
> > > DCAP user libraries are still using this ABI to support attestation over
> > > vsock model.
> > > 
> > > Don't you think we should wait till there are no users before considering
> > > removing it?
> > 
> > Given that hw with TDX was just released I'd be surprised if there are 
> > any users? But then again, this is an RFC so let's get opinions :)
> > 
> 
> The assumption is that this tdx_guest_ioctl() ABI has never appeared in
> an enterprise distro kernel. If that assumption is valid, it
> significantly reduces the long term support exposure.

This ioctl is present in current RHEL-9 kernels

  https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/blob/main/drivers/virt/coco/tdx-guest/tdx-guest.c?ref_type=heads#L69

and this is exposed to users when running RHEL-9 guest on Azure
cloud with TDX support.

I've not directly checked, but I would assume it is also probably
included in Ubuntu LTS kernels too, since they also target TDX in
Azure.

No idea what the status of SLES is wrt TDX / Azure offhand.

With regards,
Daniel
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