On Fri, Jan 08, 2021 at 12:15:24PM +0000, Quentin Perret wrote:
> When KVM runs in protected nVHE mode, make use of a stage 2 page-table
> to give the hypervisor some control over the host memory accesses. At
> the moment all memory aborts from the host will be instantly idmapped
> RWX at stage 2 in a lazy fashion. Later patches will make use of that
> infrastructure to implement access control restrictions to e.g. protect
> guest memory from the host.
>
> Signed-off-by: Quentin Perret <qperret@xxxxxxxxxx>
> ---
> arch/arm64/include/asm/kvm_cpufeature.h | 2 +
> arch/arm64/kernel/image-vars.h | 3 +
> arch/arm64/kvm/hyp/include/nvhe/mem_protect.h | 33 +++
> arch/arm64/kvm/hyp/nvhe/Makefile | 2 +-
> arch/arm64/kvm/hyp/nvhe/hyp-init.S | 1 +
> arch/arm64/kvm/hyp/nvhe/hyp-main.c | 6 +
> arch/arm64/kvm/hyp/nvhe/mem_protect.c | 191 ++++++++++++++++++
> arch/arm64/kvm/hyp/nvhe/setup.c | 6 +
> arch/arm64/kvm/hyp/nvhe/switch.c | 7 +-
> arch/arm64/kvm/hyp/nvhe/tlb.c | 4 +-
> 10 files changed, 248 insertions(+), 7 deletions(-)
> create mode 100644 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
> create mode 100644 arch/arm64/kvm/hyp/nvhe/mem_protect.c
[...]
> +void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
> +{
> + enum kvm_pgtable_prot prot;
> + u64 far, hpfar, esr, ipa;
> + int ret;
> +
> + esr = read_sysreg_el2(SYS_ESR);
> + if (!__get_fault_info(esr, &far, &hpfar))
> + hyp_panic();
> +
> + prot = KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W | KVM_PGTABLE_PROT_X;
> + ipa = (hpfar & HPFAR_MASK) << 8;
> + ret = host_stage2_map(ipa, PAGE_SIZE, prot);
Can we try to put down a block mapping if the whole thing falls within
memory?
Will
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