Re: [PATCH HVM v4 1/1] hvm: refactor set param

[Jan Beulich <jbeulich@xxxxxxxx>]

On 18.02.2021 16:01, Norbert Manthey wrote:
> To prevent leaking HVM params via L1TF and similar issues on a
> hyperthread pair, let's load values of domains only after performing all
> relevant checks, and blocking speculative execution.
> 
> For both get and set, the value of the index is already checked in the
> outer calling function. The block_speculation calls in hvmop_get_param
> and hvmop_set_param are removed, because is_hvm_domain already blocks
> speculation.
> 
> Furthermore, speculative barriers are re-arranged to make sure we do not
> allow guests running on co-located VCPUs to leak hvm parameter values of
> other domains.
> 
> To improve symmetry between the get and set operations, function
> hvmop_set_param is made static.
> 
> This is part of the speculative hardening effort.
> 
> Signed-off-by: Norbert Manthey <nmanthey@xxxxxxxxx>
> Reported-by: Hongyan Xia <hongyxia@xxxxxxxxxxxx>
> Release-Acked-by: Ian Jackson <iwj@xxxxxxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>