Introduce a new stage 2 configuration flag to specify that all mappings
in a given page-table will be identity-mapped, as will be the case for
the host. This allows to introduce sanity checks in the map path and to
avoid programming errors.
Suggested-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Quentin Perret <qperret@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_pgtable.h | 2 ++
arch/arm64/kvm/hyp/pgtable.c | 3 +++
2 files changed, 5 insertions(+)
diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index 55452f4831d2..c3674c47d48c 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -60,9 +60,11 @@ struct kvm_pgtable_mm_ops {
* enum kvm_pgtable_stage2_flags - Stage-2 page-table flags.
* @KVM_PGTABLE_S2_NOFWB: Don't enforce Normal-WB even if the CPUs have
* ARM64_HAS_STAGE2_FWB.
+ * @KVM_PGTABLE_S2_IDMAP: Only use identity mappings.
*/
enum kvm_pgtable_stage2_flags {
KVM_PGTABLE_S2_NOFWB = BIT(0),
+ KVM_PGTABLE_S2_IDMAP = BIT(1),
};
/**
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index b22b4860630c..c37c1dc4feaf 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -760,6 +760,9 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
.arg = &map_data,
};
+ if (WARN_ON((pgt->flags & KVM_PGTABLE_S2_IDMAP) && (addr != phys)))
+ return -EINVAL;
+
ret = stage2_set_prot_attr(pgt, prot, &map_data.attr);
if (ret)
return ret;
--
2.31.0.rc2.261.g7f71774620-goog
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