diff options
| -rw-r--r-- | arch/arm64/include/asm/kvm_pgtable.h | 104 | ||||
| -rw-r--r-- | arch/arm64/kvm/hyp/Makefile | 2 | ||||
| -rw-r--r-- | arch/arm64/kvm/hyp/pgtable.c | 285 |
3 files changed, 390 insertions, 1 deletions
diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h new file mode 100644 index 000000000000..9423e5d609f1 --- /dev/null +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -0,0 +1,104 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2020 Google LLC + * Author: Will Deacon <will@kernel.org> + */ + +#ifndef __ARM64_KVM_PGTABLE_H__ +#define __ARM64_KVM_PGTABLE_H__ + +#include <linux/bits.h> +#include <linux/kvm_host.h> +#include <linux/types.h> + +typedef u64 kvm_pte_t; + +/** + * struct kvm_pgtable - KVM page-table. + * @ia_bits: Maximum input address size, in bits. + * @start_level: Level at which the page-table walk starts. + * @pgd: Pointer to the first top-level entry of the page-table. + * @mmu: Stage-2 KVM MMU struct. Unused for stage-1 page-tables. + */ +struct kvm_pgtable { + u32 ia_bits; + u32 start_level; + kvm_pte_t *pgd; + + /* Stage-2 only */ + struct kvm_s2_mmu *mmu; +}; + +/** + * enum kvm_pgtable_prot - Page-table permissions and attributes. + * @KVM_PGTABLE_PROT_X: Execute permission. + * @KVM_PGTABLE_PROT_W: Write permission. + * @KVM_PGTABLE_PROT_R: Read permission. + * @KVM_PGTABLE_PROT_DEVICE: Device attributes. + */ +enum kvm_pgtable_prot { + KVM_PGTABLE_PROT_X = BIT(0), + KVM_PGTABLE_PROT_W = BIT(1), + KVM_PGTABLE_PROT_R = BIT(2), + + KVM_PGTABLE_PROT_DEVICE = BIT(3), +}; + +/** + * enum kvm_pgtable_walk_flags - Flags to control a depth-first page-table walk. + * @KVM_PGTABLE_WALK_LEAF: Visit leaf entries, including invalid + * entries. + * @KVM_PGTABLE_WALK_TABLE_PRE: Visit table entries before their + * children. + * @KVM_PGTABLE_WALK_TABLE_POST: Visit table entries after their + * children. + */ +enum kvm_pgtable_walk_flags { + KVM_PGTABLE_WALK_LEAF = BIT(0), + KVM_PGTABLE_WALK_TABLE_PRE = BIT(1), + KVM_PGTABLE_WALK_TABLE_POST = BIT(2), +}; + +typedef int (*kvm_pgtable_visitor_fn_t)(u64 addr, u64 end, u32 level, + kvm_pte_t *ptep, + enum kvm_pgtable_walk_flags flag, + void * const arg); + +/** + * struct kvm_pgtable_walker - Hook into a page-table walk. + * @cb: Callback function to invoke during the walk. + * @arg: Argument passed to the callback function. + * @flags: Bitwise-OR of flags to identify the entry types on which to + * invoke the callback function. + */ +struct kvm_pgtable_walker { + const kvm_pgtable_visitor_fn_t cb; + void * const arg; + const enum kvm_pgtable_walk_flags flags; +}; + +/** + * 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. + * @size: Size of the range to walk. + * @walker: Walker callback description. + * + * The offset of @addr within a page is ignored and @size is rounded-up to + * the next page boundary. + * + * The walker will walk the page-table entries corresponding to the input + * address range specified, visiting entries according to the walker flags. + * Invalid entries are treated as leaf entries. Leaf entries are reloaded + * after invoking the walker callback, allowing the walker to descend into + * a newly installed table. + * + * Returning a negative error code from the walker callback function will + * terminate the walk immediately with the same error code. + * + * Return: 0 on success, negative error code on failure. + */ +int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size, + struct kvm_pgtable_walker *walker); + +#endif /* __ARM64_KVM_PGTABLE_H__ */ diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile index f54f0e89a71c..607b8a898826 100644 --- a/arch/arm64/kvm/hyp/Makefile +++ b/arch/arm64/kvm/hyp/Makefile @@ -10,5 +10,5 @@ subdir-ccflags-y := -I$(incdir) \ -DDISABLE_BRANCH_PROFILING \ $(DISABLE_STACKLEAK_PLUGIN) -obj-$(CONFIG_KVM) += vhe/ nvhe/ +obj-$(CONFIG_KVM) += vhe/ nvhe/ pgtable.o obj-$(CONFIG_KVM_INDIRECT_VECTORS) += smccc_wa.o diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c new file mode 100644 index 000000000000..3fb9d1949a3f --- /dev/null +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -0,0 +1,285 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Stand-alone page-table allocator for hyp stage-1 and guest stage-2. + * No bombay mix was harmed in the writing of this file. + * + * Copyright (C) 2020 Google LLC + * Author: Will Deacon <will@kernel.org> + */ + +#include <linux/bitfield.h> +#include <asm/kvm_pgtable.h> + +#define KVM_PGTABLE_MAX_LEVELS 4U + +#define KVM_PTE_VALID BIT(0) + +#define KVM_PTE_TYPE BIT(1) +#define KVM_PTE_TYPE_BLOCK 0 +#define KVM_PTE_TYPE_PAGE 1 +#define KVM_PTE_TYPE_TABLE 1 + +#define KVM_PTE_ADDR_MASK GENMASK(47, PAGE_SHIFT) +#define KVM_PTE_ADDR_51_48 GENMASK(15, 12) + +#define KVM_PTE_LEAF_ATTR_LO GENMASK(11, 2) + +#define KVM_PTE_LEAF_ATTR_HI GENMASK(63, 51) + +struct kvm_pgtable_walk_data { + struct kvm_pgtable *pgt; + struct kvm_pgtable_walker *walker; + + u64 addr; + u64 end; +}; + +static u64 kvm_granule_shift(u32 level) +{ + /* Assumes KVM_PGTABLE_MAX_LEVELS is 4 */ + return ARM64_HW_PGTABLE_LEVEL_SHIFT(level); +} + +static u64 kvm_granule_size(u32 level) +{ + return BIT(kvm_granule_shift(level)); +} + +static bool kvm_block_mapping_supported(u64 addr, u64 end, u64 phys, u32 level) +{ + u64 granule = kvm_granule_size(level); + + /* + * Reject invalid block mappings and don't bother with 4TB mappings for + * 52-bit PAs. + */ + if (level == 0 || (PAGE_SIZE != SZ_4K && level == 1)) + return false; + + if (granule > (end - addr)) + return false; + + return IS_ALIGNED(addr, granule) && IS_ALIGNED(phys, granule); +} + +static u32 kvm_pgtable_idx(struct kvm_pgtable_walk_data *data, u32 level) +{ + u64 shift = kvm_granule_shift(level); + u64 mask = BIT(PAGE_SHIFT - 3) - 1; + + return (data->addr >> shift) & mask; +} + +static u32 __kvm_pgd_page_idx(struct kvm_pgtable *pgt, u64 addr) +{ + u64 shift = kvm_granule_shift(pgt->start_level - 1); /* May underflow */ + u64 mask = BIT(pgt->ia_bits) - 1; + + return (addr & mask) >> shift; +} + +static u32 kvm_pgd_page_idx(struct kvm_pgtable_walk_data *data) +{ + return __kvm_pgd_page_idx(data->pgt, data->addr); +} + +static u32 kvm_pgd_pages(u32 ia_bits, u32 start_level) +{ + struct kvm_pgtable pgt = { + .ia_bits = ia_bits, + .start_level = start_level, + }; + + return __kvm_pgd_page_idx(&pgt, -1ULL) + 1; +} + +static bool kvm_pte_valid(kvm_pte_t pte) +{ + return pte & KVM_PTE_VALID; +} + +static bool kvm_pte_table(kvm_pte_t pte, u32 level) +{ + if (level == KVM_PGTABLE_MAX_LEVELS - 1) + return false; + + if (!kvm_pte_valid(pte)) + return false; + + return FIELD_GET(KVM_PTE_TYPE, pte) == KVM_PTE_TYPE_TABLE; +} + +static u64 kvm_pte_to_phys(kvm_pte_t pte) +{ + u64 pa = pte & KVM_PTE_ADDR_MASK; + + if (PAGE_SHIFT == 16) + pa |= FIELD_GET(KVM_PTE_ADDR_51_48, pte) << 48; + + return pa; +} + +static kvm_pte_t kvm_phys_to_pte(u64 pa) +{ + kvm_pte_t pte = pa & KVM_PTE_ADDR_MASK; + + if (PAGE_SHIFT == 16) + pte |= FIELD_PREP(KVM_PTE_ADDR_51_48, pa >> 48); + + return pte; +} + +static kvm_pte_t *kvm_pte_follow(kvm_pte_t pte) +{ + return __va(kvm_pte_to_phys(pte)); +} + +static void kvm_set_invalid_pte(kvm_pte_t *ptep) +{ + kvm_pte_t pte = *ptep; + WRITE_ONCE(*ptep, pte & ~KVM_PTE_VALID); +} + +static void kvm_set_table_pte(kvm_pte_t *ptep, kvm_pte_t *childp) +{ + kvm_pte_t old = *ptep, pte = kvm_phys_to_pte(__pa(childp)); + + pte |= FIELD_PREP(KVM_PTE_TYPE, KVM_PTE_TYPE_TABLE); + pte |= KVM_PTE_VALID; + + WARN_ON(kvm_pte_valid(old)); + smp_store_release(ptep, pte); +} + +static bool kvm_set_valid_leaf_pte(kvm_pte_t *ptep, u64 pa, kvm_pte_t attr, + u32 level) +{ + kvm_pte_t old = *ptep, pte = kvm_phys_to_pte(pa); + u64 type = (level == KVM_PGTABLE_MAX_LEVELS - 1) ? KVM_PTE_TYPE_PAGE : + KVM_PTE_TYPE_BLOCK; + + pte |= attr & (KVM_PTE_LEAF_ATTR_LO | KVM_PTE_LEAF_ATTR_HI); + pte |= FIELD_PREP(KVM_PTE_TYPE, type); + pte |= KVM_PTE_VALID; + + /* Tolerate KVM recreating the exact same mapping. */ + if (kvm_pte_valid(old)) + return old == pte; + + smp_store_release(ptep, pte); + return true; +} + +static int kvm_pgtable_visitor_cb(struct kvm_pgtable_walk_data *data, u64 addr, + u32 level, kvm_pte_t *ptep, + enum kvm_pgtable_walk_flags flag) +{ + struct kvm_pgtable_walker *walker = data->walker; + return walker->cb(addr, data->end, level, ptep, flag, walker->arg); +} + +static int __kvm_pgtable_walk(struct kvm_pgtable_walk_data *data, + kvm_pte_t *pgtable, u32 level); + +static inline int __kvm_pgtable_visit(struct kvm_pgtable_walk_data *data, + kvm_pte_t *ptep, u32 level) +{ + int ret = 0; + u64 addr = data->addr; + kvm_pte_t *childp, pte = *ptep; + bool table = kvm_pte_table(pte, level); + enum kvm_pgtable_walk_flags flags = data->walker->flags; + + if (table && (flags & KVM_PGTABLE_WALK_TABLE_PRE)) { + ret = kvm_pgtable_visitor_cb(data, addr, level, ptep, + KVM_PGTABLE_WALK_TABLE_PRE); + } + + if (!table && (flags & KVM_PGTABLE_WALK_LEAF)) { + ret = kvm_pgtable_visitor_cb(data, addr, level, ptep, + KVM_PGTABLE_WALK_LEAF); + pte = *ptep; + table = kvm_pte_table(pte, level); + } + + if (ret) + goto out; + + if (!table) { + data->addr += kvm_granule_size(level); + goto out; + } + + childp = kvm_pte_follow(pte); + ret = __kvm_pgtable_walk(data, childp, level + 1); + if (ret) + goto out; + + if (flags & KVM_PGTABLE_WALK_TABLE_POST) { + ret = kvm_pgtable_visitor_cb(data, addr, level, ptep, + KVM_PGTABLE_WALK_TABLE_POST); + } + +out: + return ret; +} + +static int __kvm_pgtable_walk(struct kvm_pgtable_walk_data *data, + kvm_pte_t *pgtable, u32 level) +{ + u32 idx; + int ret = 0; + + if (WARN_ON_ONCE(level >= KVM_PGTABLE_MAX_LEVELS)) + return -EINVAL; + + for (idx = kvm_pgtable_idx(data, level); idx < PTRS_PER_PTE; ++idx) { + kvm_pte_t *ptep = &pgtable[idx]; + + if (data->addr >= data->end) + break; + + ret = __kvm_pgtable_visit(data, ptep, level); + if (ret) + break; + } + + return ret; +} + +static int _kvm_pgtable_walk(struct kvm_pgtable_walk_data *data) +{ + u32 idx; + int ret = 0; + struct kvm_pgtable *pgt = data->pgt; + u64 limit = BIT(pgt->ia_bits); + + if (data->addr > limit || data->end > limit) + return -ERANGE; + + if (!pgt->pgd) + return -EINVAL; + + for (idx = kvm_pgd_page_idx(data); data->addr < data->end; ++idx) { + kvm_pte_t *ptep = &pgt->pgd[idx * PTRS_PER_PTE]; + + ret = __kvm_pgtable_walk(data, ptep, pgt->start_level); + if (ret) + break; + } + + return ret; +} + +int kvm_pgtable_walk(struct kvm_pgtable *pgt, u64 addr, u64 size, + struct kvm_pgtable_walker *walker) +{ + struct kvm_pgtable_walk_data walk_data = { + .pgt = pgt, + .addr = ALIGN_DOWN(addr, PAGE_SIZE), + .end = PAGE_ALIGN(walk_data.addr + size), + .walker = walker, + }; + + return _kvm_pgtable_walk(&walk_data); +} |