[PATCH v4 3/8] KVM: arm64: Fix MTE flag initialization for protected VMs

[Ben Horgan]

Hi Fuad,

On 11/12/25 09:20, Fuad Tabba wrote:
> The function pkvm_init_features_from_host() initializes guest
> features, propagating them from the host. The logic to propagate
> KVM_ARCH_FLAG_MTE_ENABLED (Memory Tagging Extension)
> has a couple of issues.
> 
> First, the check was in the common path, before the divergence for
> protected and non-protected VMs. For non-protected VMs, this was
> unnecessary, as 'kvm->arch.flags' is completely overwritten by
> host_arch_flags immediately after, which already contains the MTE flag.
> For protected VMs, this was setting the flag even if the feature is not
> allowed.
> 
> Second, the check was reading 'host_kvm->arch.flags' instead of using
> the local 'host_arch_flags', which is read once from the host flags.
> 
> Fix these by moving the MTE flag check inside the protected-VM-only
> path, checking if the feature is allowed, and changing it to use the
> correct host_arch_flags local variable. This ensures non-protected VMs
> get the flag via the bulk copy, and protected VMs get it via an explicit
> check.
> 
> Fixes: b7f345fbc32a ("KVM: arm64: Fix FEAT_MTE in pKVM")
> Signed-off-by: Fuad Tabba <tabba at google.com>
> ---

LGTM

Reviewed-by: Ben Horgan <ben.horgan at arm.com>

Thanks,

Ben