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    Subject[PATCH 06/16] KVM: arm64: Force a full unmap on vpcu reinit
    Date
    As we now keep information in the S2PT, we must be careful not
    to keep it across a VM reboot, which could otherwise lead to
    interesting problems.

    Make sure that the S2 is completely discarded on reset of
    a vcpu, and remove the flag that enforces the MMIO check.

    Signed-off-by: Marc Zyngier <maz@kernel.org>
    ---
    arch/arm64/kvm/arm.c | 8 +++++++-
    1 file changed, 7 insertions(+), 1 deletion(-)

    diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
    index 97ab1512c44f..b0d2225190d2 100644
    --- a/arch/arm64/kvm/arm.c
    +++ b/arch/arm64/kvm/arm.c
    @@ -1096,12 +1096,18 @@ static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu,
    * ensuring that the data side is always coherent. We still
    * need to invalidate the I-cache though, as FWB does *not*
    * imply CTR_EL0.DIC.
    + *
    + * If the MMIO guard was enabled, we pay the price of a full
    + * unmap to get back to a sane state (and clear the flag).
    */
    if (vcpu->arch.has_run_once) {
    - if (!cpus_have_final_cap(ARM64_HAS_STAGE2_FWB))
    + if (!cpus_have_final_cap(ARM64_HAS_STAGE2_FWB) ||
    + test_bit(KVM_ARCH_FLAG_MMIO_GUARD, &vcpu->kvm->arch.flags))
    stage2_unmap_vm(vcpu->kvm);
    else
    icache_inval_all_pou();
    +
    + clear_bit(KVM_ARCH_FLAG_MMIO_GUARD, &vcpu->kvm->arch.flags);
    }

    vcpu_reset_hcr(vcpu);
    --
    2.30.2
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