Introduce infrastructure allowing to manipulate software bits in stage-1 and stage-2 page-tables using additional entries in the kvm_pgtable_prot enum. This is heavily inspired by Marc's implementation of a similar feature in the NV patch series, but adapted to allow stage-1 changes as well: https://lore.kernel.org/kvmarm/20210510165920.1913477-56-maz@xxxxxxxxxx/ Suggested-by: Marc Zyngier <maz@xxxxxxxxxx> Signed-off-by: Quentin Perret <qperret@xxxxxxxxxx> --- arch/arm64/include/asm/kvm_pgtable.h | 12 +++++++++++- arch/arm64/kvm/hyp/pgtable.c | 5 +++++ 2 files changed, 16 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index 9246a27e2839..0be9f83974ad 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -108,6 +108,10 @@ enum kvm_pgtable_stage2_flags { * @KVM_PGTABLE_PROT_W: Write permission. * @KVM_PGTABLE_PROT_R: Read permission. * @KVM_PGTABLE_PROT_DEVICE: Device attributes. + * @KVM_PGTABLE_PROT_SW0: Software bit 0. + * @KVM_PGTABLE_PROT_SW1: Software bit 1. + * @KVM_PGTABLE_PROT_SW2: Software bit 2. + * @KVM_PGTABLE_PROT_SW3: Software bit 3. */ enum kvm_pgtable_prot { KVM_PGTABLE_PROT_X = BIT(0), @@ -115,6 +119,11 @@ enum kvm_pgtable_prot { KVM_PGTABLE_PROT_R = BIT(2), KVM_PGTABLE_PROT_DEVICE = BIT(3), + + KVM_PGTABLE_PROT_SW0 = BIT(55), + KVM_PGTABLE_PROT_SW1 = BIT(56), + KVM_PGTABLE_PROT_SW2 = BIT(57), + KVM_PGTABLE_PROT_SW3 = BIT(58), }; #define KVM_PGTABLE_PROT_RW (KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W) @@ -406,7 +415,8 @@ kvm_pte_t kvm_pgtable_stage2_mkold(struct kvm_pgtable *pgt, u64 addr); * If there is a valid, leaf page-table entry used to translate @addr, then * relax the permissions in that entry according to the read, write and * execute permissions specified by @prot. No permissions are removed, and - * TLB invalidation is performed after updating the entry. + * TLB invalidation is performed after updating the entry. Software bits cannot + * be set or cleared using kvm_pgtable_stage2_relax_perms(). * * Return: 0 on success, negative error code on failure. */ diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index e0cd748e4af6..bd409d524dea 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -370,6 +370,7 @@ static int hyp_set_prot_attr(enum kvm_pgtable_prot prot, kvm_pte_t *ptep) attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S1_AP, ap); attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S1_SH, sh); attr |= KVM_PTE_LEAF_ATTR_LO_S1_AF; + attr |= prot & KVM_PTE_LEAF_ATTR_HI_SW; *ptep = attr; return 0; @@ -571,6 +572,7 @@ static int stage2_set_prot_attr(struct kvm_pgtable *pgt, enum kvm_pgtable_prot p attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S2_SH, sh); attr |= KVM_PTE_LEAF_ATTR_LO_S2_AF; + attr |= prot & KVM_PTE_LEAF_ATTR_HI_SW; *ptep = attr; return 0; @@ -1038,6 +1040,9 @@ int kvm_pgtable_stage2_relax_perms(struct kvm_pgtable *pgt, u64 addr, u32 level; kvm_pte_t set = 0, clr = 0; + if (prot & KVM_PTE_LEAF_ATTR_HI_SW) + return -EINVAL; + if (prot & KVM_PGTABLE_PROT_R) set |= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R; -- 2.32.0.432.gabb21c7263-goog _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
