From 6d9d2115c48027132a69477c98d812be669f5b9b Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 11 Sep 2020 14:25:14 +0100 Subject: [PATCH] KVM: arm64: Add support for stage-2 map()/unmap() in generic page-table Add stage-2 map() and unmap() operations to the generic page-table code. Signed-off-by: Will Deacon Signed-off-by: Marc Zyngier Reviewed-by: Gavin Shan Cc: Marc Zyngier Cc: Quentin Perret Link: https://lore.kernel.org/r/20200911132529.19844-7-will@kernel.org --- arch/arm64/include/asm/kvm_pgtable.h | 46 ++++++ arch/arm64/kvm/hyp/pgtable.c | 273 +++++++++++++++++++++++++++++++++++ 2 files changed, 319 insertions(+) diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index 21d71395a377..895b2238062b 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -141,6 +141,52 @@ int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm); void kvm_pgtable_stage2_destroy(struct kvm_pgtable *pgt); /** + * kvm_pgtable_stage2_map() - Install a mapping in a guest stage-2 page-table. + * @pgt: Page-table structure initialised by kvm_pgtable_stage2_init(). + * @addr: Intermediate physical address at which to place the mapping. + * @size: Size of the mapping. + * @phys: Physical address of the memory to map. + * @prot: Permissions and attributes for the mapping. + * @mc: Cache of pre-allocated GFP_PGTABLE_USER memory from which to + * allocate page-table pages. + * + * The offset of @addr within a page is ignored, @size is rounded-up to + * the next page boundary and @phys is rounded-down to the previous page + * boundary. + * + * If device attributes are not explicitly requested in @prot, then the + * mapping will be normal, cacheable. + * + * Note that this function will both coalesce existing table entries and split + * existing block mappings, relying on page-faults to fault back areas outside + * of the new mapping lazily. + * + * Return: 0 on success, negative error code on failure. + */ +int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size, + u64 phys, enum kvm_pgtable_prot prot, + struct kvm_mmu_memory_cache *mc); + +/** + * kvm_pgtable_stage2_unmap() - Remove a mapping from a guest stage-2 page-table. + * @pgt: Page-table structure initialised by kvm_pgtable_stage2_init(). + * @addr: Intermediate physical address from which to remove the mapping. + * @size: Size of the mapping. + * + * The offset of @addr within a page is ignored and @size is rounded-up to + * the next page boundary. + * + * TLB invalidation is performed for each page-table entry cleared during the + * unmapping operation and the reference count for the page-table page + * containing the cleared entry is decremented, with unreferenced pages being + * freed. Unmapping a cacheable page will ensure that it is clean to the PoC if + * FWB is not supported by the CPU. + * + * Return: 0 on success, negative error code on failure. + */ +int kvm_pgtable_stage2_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size); + +/** * kvm_pgtable_walk() - Walk a page-table. * @pgt: Page-table structure initialised by kvm_pgtable_*_init(). * @addr: Input address for the start of the walk. diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index 16b34d11e7cf..2f9b872f5355 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -32,10 +32,19 @@ #define KVM_PTE_LEAF_ATTR_LO_S1_SH_IS 3 #define KVM_PTE_LEAF_ATTR_LO_S1_AF BIT(10) +#define KVM_PTE_LEAF_ATTR_LO_S2_MEMATTR GENMASK(5, 2) +#define KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R BIT(6) +#define KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W BIT(7) +#define KVM_PTE_LEAF_ATTR_LO_S2_SH GENMASK(9, 8) +#define KVM_PTE_LEAF_ATTR_LO_S2_SH_IS 3 +#define KVM_PTE_LEAF_ATTR_LO_S2_AF BIT(10) + #define KVM_PTE_LEAF_ATTR_HI GENMASK(63, 51) #define KVM_PTE_LEAF_ATTR_HI_S1_XN BIT(54) +#define KVM_PTE_LEAF_ATTR_HI_S2_XN BIT(54) + struct kvm_pgtable_walk_data { struct kvm_pgtable *pgt; struct kvm_pgtable_walker *walker; @@ -417,6 +426,270 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt) pgt->pgd = NULL; } +struct stage2_map_data { + u64 phys; + kvm_pte_t attr; + + kvm_pte_t *anchor; + + struct kvm_s2_mmu *mmu; + struct kvm_mmu_memory_cache *memcache; +}; + +static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot, + struct stage2_map_data *data) +{ + bool device = prot & KVM_PGTABLE_PROT_DEVICE; + kvm_pte_t attr = device ? PAGE_S2_MEMATTR(DEVICE_nGnRE) : + PAGE_S2_MEMATTR(NORMAL); + u32 sh = KVM_PTE_LEAF_ATTR_LO_S2_SH_IS; + + if (!(prot & KVM_PGTABLE_PROT_X)) + attr |= KVM_PTE_LEAF_ATTR_HI_S2_XN; + else if (device) + return -EINVAL; + + if (prot & KVM_PGTABLE_PROT_R) + attr |= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R; + + if (prot & KVM_PGTABLE_PROT_W) + attr |= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W; + + attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S2_SH, sh); + attr |= KVM_PTE_LEAF_ATTR_LO_S2_AF; + data->attr = attr; + return 0; +} + +static bool stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level, + kvm_pte_t *ptep, + struct stage2_map_data *data) +{ + u64 granule = kvm_granule_size(level), phys = data->phys; + + if (!kvm_block_mapping_supported(addr, end, phys, level)) + return false; + + if (kvm_set_valid_leaf_pte(ptep, phys, data->attr, level)) + goto out; + + /* There's an existing valid leaf entry, so perform break-before-make */ + kvm_set_invalid_pte(ptep); + kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level); + kvm_set_valid_leaf_pte(ptep, phys, data->attr, level); +out: + data->phys += granule; + return true; +} + +static int stage2_map_walk_table_pre(u64 addr, u64 end, u32 level, + kvm_pte_t *ptep, + struct stage2_map_data *data) +{ + if (data->anchor) + return 0; + + if (!kvm_block_mapping_supported(addr, end, data->phys, level)) + return 0; + + kvm_set_invalid_pte(ptep); + kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, 0); + data->anchor = ptep; + return 0; +} + +static int stage2_map_walk_leaf(u64 addr, u64 end, u32 level, kvm_pte_t *ptep, + struct stage2_map_data *data) +{ + kvm_pte_t *childp, pte = *ptep; + struct page *page = virt_to_page(ptep); + + if (data->anchor) { + if (kvm_pte_valid(pte)) + put_page(page); + + return 0; + } + + if (stage2_map_walker_try_leaf(addr, end, level, ptep, data)) + goto out_get_page; + + if (WARN_ON(level == KVM_PGTABLE_MAX_LEVELS - 1)) + return -EINVAL; + + if (!data->memcache) + return -ENOMEM; + + childp = kvm_mmu_memory_cache_alloc(data->memcache); + if (!childp) + return -ENOMEM; + + /* + * If we've run into an existing block mapping then replace it with + * a table. Accesses beyond 'end' that fall within the new table + * will be mapped lazily. + */ + if (kvm_pte_valid(pte)) { + kvm_set_invalid_pte(ptep); + kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, data->mmu, addr, level); + put_page(page); + } + + kvm_set_table_pte(ptep, childp); + +out_get_page: + get_page(page); + return 0; +} + +static int stage2_map_walk_table_post(u64 addr, u64 end, u32 level, + kvm_pte_t *ptep, + struct stage2_map_data *data) +{ + int ret = 0; + + if (!data->anchor) + return 0; + + free_page((unsigned long)kvm_pte_follow(*ptep)); + put_page(virt_to_page(ptep)); + + if (data->anchor == ptep) { + data->anchor = NULL; + ret = stage2_map_walk_leaf(addr, end, level, ptep, data); + } + + return ret; +} + +/* + * This is a little fiddly, as we use all three of the walk flags. The idea + * is that the TABLE_PRE callback runs for table entries on the way down, + * looking for table entries which we could conceivably replace with a + * block entry for this mapping. If it finds one, then it sets the 'anchor' + * field in 'struct stage2_map_data' to point at the table entry, before + * clearing the entry to zero and descending into the now detached table. + * + * The behaviour of the LEAF callback then depends on whether or not the + * anchor has been set. If not, then we're not using a block mapping higher + * up the table and we perform the mapping at the existing leaves instead. + * If, on the other hand, the anchor _is_ set, then we drop references to + * all valid leaves so that the pages beneath the anchor can be freed. + * + * Finally, the TABLE_POST callback does nothing if the anchor has not + * been set, but otherwise frees the page-table pages while walking back up + * the page-table, installing the block entry when it revisits the anchor + * pointer and clearing the anchor to NULL. + */ +static int stage2_map_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep, + enum kvm_pgtable_walk_flags flag, void * const arg) +{ + struct stage2_map_data *data = arg; + + switch (flag) { + case KVM_PGTABLE_WALK_TABLE_PRE: + return stage2_map_walk_table_pre(addr, end, level, ptep, data); + case KVM_PGTABLE_WALK_LEAF: + return stage2_map_walk_leaf(addr, end, level, ptep, data); + case KVM_PGTABLE_WALK_TABLE_POST: + return stage2_map_walk_table_post(addr, end, level, ptep, data); + } + + return -EINVAL; +} + +int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size, + u64 phys, enum kvm_pgtable_prot prot, + struct kvm_mmu_memory_cache *mc) +{ + int ret; + struct stage2_map_data map_data = { + .phys = ALIGN_DOWN(phys, PAGE_SIZE), + .mmu = pgt->mmu, + .memcache = mc, + }; + struct kvm_pgtable_walker walker = { + .cb = stage2_map_walker, + .flags = KVM_PGTABLE_WALK_TABLE_PRE | + KVM_PGTABLE_WALK_LEAF | + KVM_PGTABLE_WALK_TABLE_POST, + .arg = &map_data, + }; + + ret = stage2_map_set_prot_attr(prot, &map_data); + if (ret) + return ret; + + ret = kvm_pgtable_walk(pgt, addr, size, &walker); + dsb(ishst); + return ret; +} + +static void stage2_flush_dcache(void *addr, u64 size) +{ + if (cpus_have_const_cap(ARM64_HAS_STAGE2_FWB)) + return; + + __flush_dcache_area(addr, size); +} + +static bool stage2_pte_cacheable(kvm_pte_t pte) +{ + u64 memattr = FIELD_GET(KVM_PTE_LEAF_ATTR_LO_S2_MEMATTR, pte); + return memattr == PAGE_S2_MEMATTR(NORMAL); +} + +static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep, + enum kvm_pgtable_walk_flags flag, + void * const arg) +{ + struct kvm_s2_mmu *mmu = arg; + kvm_pte_t pte = *ptep, *childp = NULL; + bool need_flush = false; + + if (!kvm_pte_valid(pte)) + return 0; + + if (kvm_pte_table(pte, level)) { + childp = kvm_pte_follow(pte); + + if (page_count(virt_to_page(childp)) != 1) + return 0; + } else if (stage2_pte_cacheable(pte)) { + need_flush = true; + } + + /* + * This is similar to the map() path in that we unmap the entire + * block entry and rely on the remaining portions being faulted + * back lazily. + */ + kvm_set_invalid_pte(ptep); + kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu, addr, level); + put_page(virt_to_page(ptep)); + + if (need_flush) { + stage2_flush_dcache(kvm_pte_follow(pte), + kvm_granule_size(level)); + } + + if (childp) + free_page((unsigned long)childp); + + return 0; +} + +int kvm_pgtable_stage2_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size) +{ + struct kvm_pgtable_walker walker = { + .cb = stage2_unmap_walker, + .arg = pgt->mmu, + .flags = KVM_PGTABLE_WALK_LEAF | KVM_PGTABLE_WALK_TABLE_POST, + }; + + return kvm_pgtable_walk(pgt, addr, size, &walker); +} + int kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm *kvm) { size_t pgd_sz; -- 2.11.0