Re: [PATCH v4 16/21] KVM: arm64: Enable retrieving protections attributes of PTEs
From: Fuad Tabba <hidden>
Date: 2021-08-10 04:39:12
Also in:
linux-arm-kernel, lkml
Hi Quentin, On Mon, Aug 9, 2021 at 5:25 PM Quentin Perret [off-list ref] wrote:
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 <redacted> ---
Reviewed-by: Fuad Tabba <redacted> Thanks, /fuad
quoted hunk ↗ jump to hunk
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 ff9d52f8073a..f1651e0153ad 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h@@ -506,4 +506,24 @@ 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)) --2.32.0.605.g8dce9f2422-goog
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