--- /dev/null
+// 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__ */
--- /dev/null
+// 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);
+}
projects / users / hch / configfs.git / commitdiff