[PATCH] KVM: arm64: Fix FEAT_MTE in pKVM

[PATCH] KVM: arm64: Fix FEAT_MTE in pKVM

[Vladimir Murzin]

Make sure we do not trap access to Allocation Tags.

Fixes: b56680de9c64 ("KVM: arm64: Initialize trap register values in hyp in pKVM")
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
---
 arch/arm64/kvm/hyp/nvhe/pkvm.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
index 071993c16d..dd55bff6a6 100644
--- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
+++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
@@ -229,6 +229,9 @@ static void pkvm_vcpu_reset_hcr(struct kvm_vcpu *vcpu)
 
 	if (vcpu_has_ptrauth(vcpu))
 		vcpu->arch.hcr_el2 |= (HCR_API | HCR_APK);
+
+	if (kvm_has_mte(vcpu->kvm))
+		vcpu->arch.hcr_el2 |= HCR_ATA;
 }
 
 /*
@@ -332,6 +335,9 @@ static void pkvm_init_features_from_host(struct pkvm_hyp_vm *hyp_vm, const struc
 	struct kvm *kvm = &hyp_vm->kvm;
 	DECLARE_BITMAP(allowed_features, KVM_VCPU_MAX_FEATURES);
 
+	if (test_bit(KVM_ARCH_FLAG_MTE_ENABLED, &host_kvm->arch.flags))
+		set_bit(KVM_ARCH_FLAG_MTE_ENABLED, &kvm->arch.flags);
+
 	/* No restrictions for non-protected VMs. */
 	if (!kvm_vm_is_protected(kvm)) {
 		bitmap_copy(kvm->arch.vcpu_features,
-- 
2.24.0

Re: [PATCH] KVM: arm64: Fix FEAT_MTE in pKVM

[Fuad Tabba]

Hi Vladimir,

On Mon, 6 Jan 2025 at 11:24, Vladimir Murzin <vladimir.murzin@arm.com> wrote:
>
> Make sure we do not trap access to Allocation Tags.
>
> Fixes: b56680de9c64 ("KVM: arm64: Initialize trap register values in hyp in pKVM")
> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>

Reviewed-by: Fuad Tabba <tabba@google.com>

Cheers,
/fuad
> ---
>  arch/arm64/kvm/hyp/nvhe/pkvm.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
> index 071993c16d..dd55bff6a6 100644
> --- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
> +++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
> @@ -229,6 +229,9 @@ static void pkvm_vcpu_reset_hcr(struct kvm_vcpu *vcpu)
>
>         if (vcpu_has_ptrauth(vcpu))
>                 vcpu->arch.hcr_el2 |= (HCR_API | HCR_APK);
> +
> +       if (kvm_has_mte(vcpu->kvm))
> +               vcpu->arch.hcr_el2 |= HCR_ATA;
>  }
>
>  /*
> @@ -332,6 +335,9 @@ static void pkvm_init_features_from_host(struct pkvm_hyp_vm *hyp_vm, const struc
>         struct kvm *kvm = &hyp_vm->kvm;
>         DECLARE_BITMAP(allowed_features, KVM_VCPU_MAX_FEATURES);
>
> +       if (test_bit(KVM_ARCH_FLAG_MTE_ENABLED, &host_kvm->arch.flags))
> +               set_bit(KVM_ARCH_FLAG_MTE_ENABLED, &kvm->arch.flags);
> +
>         /* No restrictions for non-protected VMs. */
>         if (!kvm_vm_is_protected(kvm)) {
>                 bitmap_copy(kvm->arch.vcpu_features,
> --
> 2.24.0
>

Re: [PATCH] KVM: arm64: Fix FEAT_MTE in pKVM

[Oliver Upton]

On Mon, Jan 06, 2025 at 11:24:21AM +0000, Vladimir Murzin wrote:
> Make sure we do not trap access to Allocation Tags.
> 
> Fixes: b56680de9c64 ("KVM: arm64: Initialize trap register values in hyp in pKVM")
> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>

I imagine Marc will pick this up for 6.14, so:

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>

-- 
Thanks,
Oliver

Re: [PATCH] KVM: arm64: Fix FEAT_MTE in pKVM

[Marc Zyngier]

On Mon, 06 Jan 2025 11:24:21 +0000, Vladimir Murzin wrote:
> Make sure we do not trap access to Allocation Tags.
> 
> 

Applied to next, thanks!

[1/1] KVM: arm64: Fix FEAT_MTE in pKVM
      commit: b7f345fbc32afab0f0b03c71c7eaf48b9a0ad7ed

Cheers,

	M.
-- 
Without deviation from the norm, progress is not possible.