From 9024b3d0069ab4b8ef70cf55f0ee09e61f3a0747 Mon Sep 17 00:00:00 2001 From: Quentin Perret Date: Mon, 9 Aug 2021 16:24:43 +0100 Subject: [PATCH] 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 Reviewed-by: Fuad Tabba Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20210809152448.1810400-17-qperret@google.com --- arch/arm64/include/asm/kvm_pgtable.h | 20 +++++++++++++++++++ arch/arm64/kvm/hyp/pgtable.c | 37 ++++++++++++++++++++++++++++++++++++ 2 files changed, 57 insertions(+) diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index bfea573703d7..027783829584 100644 --- 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 cff744136044..f8ceebe4982e 100644 --- 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)) -- 2.11.0