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| author | Fuad Tabba <tabba@google.com> | 2025-12-11 10:47:03 +0000 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2026-01-15 15:43:15 +0000 |
| commit | ebbcaece84738f71b35f32339bdeb8776004e641 (patch) | |
| tree | 092bda6caeb9b20df4afd245ca71574224cf6797 | |
| parent | e913c7ce9e6f62038a486218f43f699fc443e3e1 (diff) | |
| download | linux-ebbcaece84738f71b35f32339bdeb8776004e641.tar.gz linux-ebbcaece84738f71b35f32339bdeb8776004e641.zip | |
KVM: arm64: Fix MTE flag initialization for protected VMs
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")
Reviewed-by: Ben Horgan <ben.horgan@arm.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://patch.msgid.link/20251211104710.151771-4-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
| -rw-r--r-- | arch/arm64/kvm/hyp/nvhe/pkvm.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c index 6bd539646204..d99137dddb1f 100644 --- a/arch/arm64/kvm/hyp/nvhe/pkvm.c +++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c @@ -340,9 +340,6 @@ static void pkvm_init_features_from_host(struct pkvm_hyp_vm *hyp_vm, const struc /* Preserve the vgic model so that GICv3 emulation works */ hyp_vm->kvm.arch.vgic.vgic_model = host_kvm->arch.vgic.vgic_model; - 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)) { hyp_vm->kvm.arch.flags = host_arch_flags; @@ -357,6 +354,9 @@ static void pkvm_init_features_from_host(struct pkvm_hyp_vm *hyp_vm, const struc return; } + if (kvm_pvm_ext_allowed(KVM_CAP_ARM_MTE)) + kvm->arch.flags |= host_arch_flags & BIT(KVM_ARCH_FLAG_MTE_ENABLED); + bitmap_zero(allowed_features, KVM_VCPU_MAX_FEATURES); set_bit(KVM_ARM_VCPU_PSCI_0_2, allowed_features); |