[PATCH v2 1/5] KVM: arm64: Fix Trace Buffer trapping for protected VMs

[Suzuki K Poulose]

On 06/11/2025 14:44, Fuad Tabba wrote:
> For protected VMs in pKVM, the hypervisor should trap accesses to trace
> buffer system registers if Trace Buffer isn't supported by the VM.
> However, the current code only traps if Trace Buffer External Mode isn't
> supported.
> 
> Fix this by checking for FEAT_TRBE (Trace Buffer) rather than
> FEAT_TRBE_EXT.
> 
> Fixes: 9d5261269098 ("KVM: arm64: Trap external trace for protected VMs")
> Reported-by: Suzuki K Poulose <suzuki.poulose at arm.com>
> Signed-off-by: Fuad Tabba <tabba at google.com>
> ---
>   arch/arm64/kvm/hyp/nvhe/pkvm.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
> index 43bde061b65d..8d06a246dfd1 100644
> --- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
> +++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
> @@ -117,7 +117,7 @@ static void pvm_init_traps_mdcr(struct kvm_vcpu *vcpu)
>   	if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, TraceFilt, IMP))
>   		val |= MDCR_EL2_TTRF;
>   
> -	if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, ExtTrcBuff, IMP))
> +	if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, TraceBuffer, IMP))
>   		val |= MDCR_EL2_E2TB_MASK;


Reviewed-by: Suzuki K Poulose <suzuki.poulose at arm.com>