From: Jack Thomson <[email protected]> Allow callers of kvm_pgtable_get_leaf() to specify the page-table walk flags, in preparation for performing walks under the MMU read lock.
Reading a stage-2 leaf while only holding the read lock requires KVM_PGTABLE_WALK_SHARED: parallel faults (which also only hold the read lock) can unlink table pages and free them via RCU, so the walker must be inside an RCU read-side critical section, which the shared walk flag provides via kvm_pgtable_walk_begin(). All existing callers either hold the write lock, walk with interrupts disabled, or run at hyp where shared walks are rejected; they keep the current behaviour by passing no flags. No functional change intended. Signed-off-by: Jack Thomson <[email protected]> --- arch/arm64/include/asm/kvm_pgtable.h | 5 ++++- arch/arm64/kvm/hyp/nvhe/mem_protect.c | 10 +++++----- arch/arm64/kvm/hyp/pgtable.c | 5 +++-- arch/arm64/kvm/mmu.c | 2 +- arch/arm64/kvm/nested.c | 2 +- 5 files changed, 14 insertions(+), 10 deletions(-) diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index 41a8687938eb..d0167f7dfbee 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -859,6 +859,8 @@ int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size, * @addr: Input address for the start of the walk. * @ptep: Pointer to storage for the retrieved PTE. * @level: Pointer to storage for the level of the retrieved PTE. + * @flags: Flags to control the page-table walk + * (see struct kvm_pgtable_visit_ctx). * * The offset of @addr within a page is ignored. * @@ -869,7 +871,8 @@ int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size, * Return: 0 on success, negative error code on failure. */ int kvm_pgtable_get_leaf(struct kvm_pgtable *pgt, u64 addr, - kvm_pte_t *ptep, s8 *level); + kvm_pte_t *ptep, s8 *level, + enum kvm_pgtable_walk_flags flags); /** * kvm_pgtable_stage2_pte_prot() - Retrieve the protection attributes of a diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c index 25f04629014e..3b765c9ff7e8 100644 --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c @@ -522,7 +522,7 @@ static int host_stage2_adjust_range(u64 addr, struct kvm_mem_range *range) int ret; hyp_assert_lock_held(&host_mmu.lock); - ret = kvm_pgtable_get_leaf(&host_mmu.pgt, addr, &pte, &level); + ret = kvm_pgtable_get_leaf(&host_mmu.pgt, addr, &pte, &level, 0); if (ret) return ret; @@ -890,7 +890,7 @@ static int get_valid_guest_pte(struct pkvm_hyp_vm *vm, u64 ipa, kvm_pte_t *ptep, s8 level; int ret; - ret = kvm_pgtable_get_leaf(&vm->pgt, ipa, &pte, &level); + ret = kvm_pgtable_get_leaf(&vm->pgt, ipa, &pte, &level, 0); if (ret) return ret; if (guest_pte_is_poisoned(pte)) @@ -939,7 +939,7 @@ int __pkvm_vcpu_in_poison_fault(struct pkvm_hyp_vcpu *hyp_vcpu) ipa |= FAR_TO_FIPA_OFFSET(kvm_vcpu_get_hfar(&hyp_vcpu->vcpu)); guest_lock_component(vm); - ret = kvm_pgtable_get_leaf(&vm->pgt, ipa, &pte, &level); + ret = kvm_pgtable_get_leaf(&vm->pgt, ipa, &pte, &level, 0); if (ret) goto unlock; @@ -1293,7 +1293,7 @@ static int host_stage2_get_guest_info(phys_addr_t phys, struct pkvm_hyp_vm **vm, return -EPERM; } - ret = kvm_pgtable_get_leaf(&host_mmu.pgt, phys, &pte, &level); + ret = kvm_pgtable_get_leaf(&host_mmu.pgt, phys, &pte, &level, 0); if (ret) return ret; @@ -1522,7 +1522,7 @@ static int __check_host_shared_guest(struct pkvm_hyp_vm *vm, u64 *__phys, u64 ip s8 level; int ret; - ret = kvm_pgtable_get_leaf(&vm->pgt, ipa, &pte, &level); + ret = kvm_pgtable_get_leaf(&vm->pgt, ipa, &pte, &level, 0); if (ret) return ret; if (!kvm_pte_valid(pte)) diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index 0c1defa5fb0f..6a839a32e246 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -298,12 +298,13 @@ static int leaf_walker(const struct kvm_pgtable_visit_ctx *ctx, } int kvm_pgtable_get_leaf(struct kvm_pgtable *pgt, u64 addr, - kvm_pte_t *ptep, s8 *level) + kvm_pte_t *ptep, s8 *level, + enum kvm_pgtable_walk_flags flags) { struct leaf_walk_data data; struct kvm_pgtable_walker walker = { .cb = leaf_walker, - .flags = KVM_PGTABLE_WALK_LEAF, + .flags = flags | KVM_PGTABLE_WALK_LEAF, .arg = &data, }; int ret; diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 4da9281312eb..c720f07cb82e 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -839,7 +839,7 @@ static int get_user_mapping_size(struct kvm *kvm, u64 addr) * IPI-ing threads). */ local_irq_save(flags); - ret = kvm_pgtable_get_leaf(&pgt, addr, &pte, &level); + ret = kvm_pgtable_get_leaf(&pgt, addr, &pte, &level, 0); local_irq_restore(flags); if (ret) diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c index 38f672e94087..e45aed6d9e65 100644 --- a/arch/arm64/kvm/nested.c +++ b/arch/arm64/kvm/nested.c @@ -559,7 +559,7 @@ static u8 get_guest_mapping_ttl(struct kvm_s2_mmu *mmu, u64 addr) return 0; tmp &= ~(sz - 1); - if (kvm_pgtable_get_leaf(mmu->pgt, tmp, &pte, NULL)) + if (kvm_pgtable_get_leaf(mmu->pgt, tmp, &pte, NULL, 0)) goto again; if (!(pte & PTE_VALID)) goto again; -- 2.43.0
