Re: [PATCH 3/3] KVM: Explicitly disallow activatating a gfn_to_pfn_cache with INVALID_GPA

[Paul Durrant]

On 20/03/2024 00:15, Sean Christopherson wrote:
> Explicit disallow activating a gfn_to_pfn_cache with an error gpa, i.e.
> INVALID_GPA, to ensure that KVM doesn't mistake a GPA-based cache for an
> HVA-based cache (KVM uses INVALID_GPA as a magic value to differentiate
> between GPA-based and HVA-based caches).
>
> WARN if KVM attempts to activate a cache with INVALID_GPA, purely so that
> new caches need to at least consider what to do with a "bad" GPA, as all
> existing usage of kvm_gpc_activate() guarantees gpa != INVALID_GPA.  I.e.
> removing the WARN in the future is completely reasonable if doing so would
> yield cleaner/better code overall.
>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> ---
>   virt/kvm/pfncache.c | 7 +++++++
>   1 file changed, 7 insertions(+)

Reviewed-by: Paul Durrant <paul@xxxxxxx>