Re: [PATCH 3/5] KVM: x86/xen: Consult kvm_xen_enabled when checking for Xen MSR writes

[Paul Durrant]

On 01/02/2025 01:13, Sean Christopherson wrote:
> Query kvm_xen_enabled when detecting writes to the Xen hypercall page MSR
> so that the check is optimized away in the likely scenario that Xen isn't
> enabled for the VM.
>
> Deliberately open code the check instead of using kvm_xen_msr_enabled() in
> order to avoid a double load of xen_hvm_config.msr (which is admittedly
> rather pointless given the widespread lack of READ_ONCE() usage on the
> plethora of vCPU-scoped accesses to kvm->arch.xen state).
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> ---
>   arch/x86/kvm/xen.h | 3 +++
>   1 file changed, 3 insertions(+)

Reviewed-by: Paul Durrant <paul@xxxxxxx>