Re: [PATCH v2 0/8] x86/PV: avoid speculation abuse through guest accessors

[Ian Jackson <iwj@xxxxxxxxxxxxxx>]

Jan Beulich writes ("[PATCH v2 0/8] x86/PV: avoid speculation abuse through 
guest accessors"):
> Re-sending primarily for the purpose of getting a release ack, an
> explicit release nak, or an indication of there not being a need,
> all for at least the first three patches here (which are otherwise
> ready to go in). I've dropped the shadow part of the series from
> this re-submission, because it has all got reviewed by Tim already
> and is intended for 4.16 only anyway. I'm re-including the follow
> up patches getting the code base in consistent shape again, as I
> continue to think this consistency goal is at least worth a
> consideration towards a freeze exception.
> 
> 1: split __{get,put}_user() into "guest" and "unsafe" variants
> 2: split __copy_{from,to}_user() into "guest" and "unsafe" variants
> 3: PV: harden guest memory accesses against speculative abuse

These three:

Release-Acked-by: Ian Jackson <iwj@xxxxxxxxxxxxxx>

On the grounds that this is probably severe enough to be a blocking
issue for 4.15.

> 4: rename {get,put}_user() to {get,put}_guest()
> 5: gdbsx: convert "user" to "guest" accesses
> 6: rename copy_{from,to}_user() to copy_{from,to}_guest_pv()
> 7: move stac()/clac() from {get,put}_unsafe_asm() ...
> 8: PV: use get_unsafe() instead of copy_from_unsafe()

These have not got a maintainer review yet.  To grant a release-ack
I'd like an explanation of the downsides and upsides of taking this
series in 4.15 ?

You say "consistency" but in practical terms, what will happen if the
code is not "conxistent" in this sense ?

I'd also like to hear from aother hypervisor maintainer.

Thanks,
Ian.