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| author | Fuad Tabba <fuad.tabba@linux.dev> | 2026-10-12 17:15:22 +0100 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2026-10-26 07:44:46 +0000 |
| commit | fb77bb2a0ff253e6c370ec7dc1afa45b2ecd8d2e (patch) | |
| tree | 1c550bbc22d8f99903b5f7d5e20eff11767be834 | |
| parent | 121d74bee8cd81ce9212837db98ceaef2e530637 (diff) | |
| download | linux-fb77bb2a0ff253e6c370ec7dc1afa45b2ecd8d2e.tar.gz linux-fb77bb2a0ff253e6c370ec7dc1afa45b2ecd8d2e.zip | |
KVM: arm64: Validate the host-provided vgic model in pKVM
EL2 copies vgic_model from the host's struct kvm unchecked, and the nVHE
world switch dispatches on it with no cpucap guard. A host writing
KVM_DEV_TYPE_ARM_VGIC_V5 makes EL2 access GICv5 CPU interface registers
that are UNDEFINED without FEAT_GCIE, and panics the hypervisor on any
GICv3 machine.
Accept only GICv3, the one model pKVM supports, and force anything else
to 0, as for a VM with no in-kernel irqchip. EL2 reads the model only to
pick the GICv5 world switch and to emulate GICv3 CPU interface accesses,
and the host's own copy is left alone.
Fixes: 9b8e3d4ca0e73 ("KVM: arm64: gic-v5: Implement GICv5 load/put and save/restore")
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
Link: https://patch.msgid.link/20261012161524.4016464-4-fuad.tabba@linux.dev
Signed-off-by: Marc Zyngier <maz@kernel.org>
| -rw-r--r-- | arch/arm64/kvm/hyp/nvhe/pkvm.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c index 459bd9eb7e4b..a9d0e9470919 100644 --- a/arch/arm64/kvm/hyp/nvhe/pkvm.c +++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c @@ -340,13 +340,19 @@ static void pkvm_init_features_from_host(struct pkvm_hyp_vm *hyp_vm, const struc { struct kvm *kvm = &hyp_vm->kvm; unsigned long host_arch_flags = READ_ONCE(host_kvm->arch.flags); + u32 vgic_model = READ_ONCE(host_kvm->arch.vgic.vgic_model); DECLARE_BITMAP(allowed_features, KVM_VCPU_MAX_FEATURES); /* CTR_EL0 is always under host control, even for protected VMs. */ hyp_vm->kvm.arch.ctr_el0 = host_kvm->arch.ctr_el0; - /* Preserve the vgic model so that GICv3 emulation works */ - hyp_vm->kvm.arch.vgic.vgic_model = host_kvm->arch.vgic.vgic_model; + /* + * pKVM runs only GICv3. Anything else becomes 0, the model of a VM + * with no in-kernel irqchip, which keeps EL2 off the GICv5 registers. + */ + if (vgic_model != KVM_DEV_TYPE_ARM_VGIC_V3) + vgic_model = 0; + hyp_vm->kvm.arch.vgic.vgic_model = vgic_model; /* No restrictions for non-protected VMs. */ if (!kvm_vm_is_protected(kvm)) { |