Re: [XEN PATCH v4 05/14] x86: introduce using_{svm,vmx}() helpers

[Jan Beulich <jbeulich@xxxxxxxx>]

On 09.07.2024 07:54, Sergiy Kibrik wrote:
> As we now have SVM/VMX config options for enabling/disabling these features
> completely in the build, we need some build-time checks to ensure that vmx/svm
> code can be used and things compile. Macros cpu_has_{svm,vmx} used to be doing
> such checks at runtime, however they do not check if SVM/VMX support is
> enabled in the build.
> 
> Also cpu_has_{svm,vmx} can potentially be called from non-{VMX,SVM} build
> yet running on {VMX,SVM}-enabled CPU, so would correctly indicate that VMX/SVM
> is indeed supported by CPU, but code to drive it can't be used.
> 
> New routines using_{vmx,svm}() indicate that both CPU _and_ build provide
> corresponding technology support, while cpu_has_{vmx,svm} still remains for
> informational runtime purpose, just as their naming suggests.
> 
> These new helpers are used right away in several sites, namely guard calls to
> start_nested_{svm,vmx} and start_{svm,vmx} to fix a build when VMX=n or SVM=n.
> 
> Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>