KVM: arm64: Enable retrieving protections attributes of PTEs

Introduce helper functions in the KVM stage-2 and stage-1 page-table
manipulation library allowing to retrieve the enum kvm_pgtable_prot of a
PTE. This will be useful to implement custom walkers outside of
pgtable.c.

Signed-off-by: Quentin Perret <qperret@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210809152448.1810400-17-qperret@google.com

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index bfea573703d7f8b34bd8a6db99d7d53d5015d954..0277838295840c6ee2c4d4b79040034f2abc37fb 100644 (file)
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -507,4 +507,24 @@ int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size,
  */
 int kvm_pgtable_get_leaf(struct kvm_pgtable *pgt, u64 addr,
                         kvm_pte_t *ptep, u32 *level);
+
+/**
+ * kvm_pgtable_stage2_pte_prot() - Retrieve the protection attributes of a
+ *                                stage-2 Page-Table Entry.
+ * @pte:       Page-table entry
+ *
+ * Return: protection attributes of the page-table entry in the enum
+ *        kvm_pgtable_prot format.
+ */
+enum kvm_pgtable_prot kvm_pgtable_stage2_pte_prot(kvm_pte_t pte);
+
+/**
+ * kvm_pgtable_hyp_pte_prot() - Retrieve the protection attributes of a stage-1
+ *                             Page-Table Entry.
+ * @pte:       Page-table entry
+ *
+ * Return: protection attributes of the page-table entry in the enum
+ *        kvm_pgtable_prot format.
+ */
+enum kvm_pgtable_prot kvm_pgtable_hyp_pte_prot(kvm_pte_t pte);
 #endif /* __ARM64_KVM_PGTABLE_H__ */

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index cff7441360448f025ac6dfe04534a6086d994aa4..f8ceebe4982eb130b884800bfea771cd1353d4db 100644 (file)
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -363,6 +363,26 @@ static int hyp_set_prot_attr(enum kvm_pgtable_prot prot, kvm_pte_t *ptep)
        return 0;
 }
 
+enum kvm_pgtable_prot kvm_pgtable_hyp_pte_prot(kvm_pte_t pte)
+{
+       enum kvm_pgtable_prot prot = pte & KVM_PTE_LEAF_ATTR_HI_SW;
+       u32 ap;
+
+       if (!kvm_pte_valid(pte))
+               return prot;
+
+       if (!(pte & KVM_PTE_LEAF_ATTR_HI_S1_XN))
+               prot |= KVM_PGTABLE_PROT_X;
+
+       ap = FIELD_GET(KVM_PTE_LEAF_ATTR_LO_S1_AP, pte);
+       if (ap == KVM_PTE_LEAF_ATTR_LO_S1_AP_RO)
+               prot |= KVM_PGTABLE_PROT_R;
+       else if (ap == KVM_PTE_LEAF_ATTR_LO_S1_AP_RW)
+               prot |= KVM_PGTABLE_PROT_RW;
+
+       return prot;
+}
+
 static bool hyp_pte_needs_update(kvm_pte_t old, kvm_pte_t new)
 {
        /*
@@ -565,6 +585,23 @@ static int stage2_set_prot_attr(struct kvm_pgtable *pgt, enum kvm_pgtable_prot p
        return 0;
 }
 
+enum kvm_pgtable_prot kvm_pgtable_stage2_pte_prot(kvm_pte_t pte)
+{
+       enum kvm_pgtable_prot prot = pte & KVM_PTE_LEAF_ATTR_HI_SW;
+
+       if (!kvm_pte_valid(pte))
+               return prot;
+
+       if (pte & KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R)
+               prot |= KVM_PGTABLE_PROT_R;
+       if (pte & KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W)
+               prot |= KVM_PGTABLE_PROT_W;
+       if (!(pte & KVM_PTE_LEAF_ATTR_HI_S2_XN))
+               prot |= KVM_PGTABLE_PROT_X;
+
+       return prot;
+}
+
 static bool stage2_pte_needs_update(kvm_pte_t old, kvm_pte_t new)
 {
        if (!kvm_pte_valid(old) || !kvm_pte_valid(new))