arch/arm64/kvm/hyp/nvhe/mem_protect.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2020 Google LLC
   4  * Author: Quentin Perret <qperret@google.com>
   5  */
   6
   7 #include <linux/kvm_host.h>
   8 #include <asm/kvm_emulate.h>
   9 #include <asm/kvm_hyp.h>
  10 #include <asm/kvm_mmu.h>
  11 #include <asm/kvm_pgtable.h>
  12 #include <asm/stage2_pgtable.h>
  13
  14 #include <hyp/switch.h>
  15
  16 #include <nvhe/gfp.h>
  17 #include <nvhe/memory.h>
  18 #include <nvhe/mem_protect.h>
  19 #include <nvhe/mm.h>
  20
  21 #define KVM_HOST_S2_FLAGS (KVM_PGTABLE_S2_NOFWB | KVM_PGTABLE_S2_IDMAP)
  22
  23 extern unsigned long hyp_nr_cpus;
  24 struct host_kvm host_kvm;
  25
  26 static struct hyp_pool host_s2_pool;
  27
  28 /*
  29  * Copies of the host's CPU features registers holding sanitized values.
  30  */
  31 u64 id_aa64mmfr0_el1_sys_val;
  32 u64 id_aa64mmfr1_el1_sys_val;
  33
  34 static const u8 pkvm_hyp_id = 1;
  35
  36 static void *host_s2_zalloc_pages_exact(size_t size)
  37 {
  38         return hyp_alloc_pages(&host_s2_pool, get_order(size));
  39 }
  40
  41 static void *host_s2_zalloc_page(void *pool)
  42 {
  43         return hyp_alloc_pages(pool, 0);
  44 }
  45
  46 static void host_s2_get_page(void *addr)
  47 {
  48         hyp_get_page(&host_s2_pool, addr);
  49 }
  50
  51 static void host_s2_put_page(void *addr)
  52 {
  53         hyp_put_page(&host_s2_pool, addr);
  54 }
  55
  56 static int prepare_s2_pool(void *pgt_pool_base)
  57 {
  58         unsigned long nr_pages, pfn;
  59         int ret;
  60
  61         pfn = hyp_virt_to_pfn(pgt_pool_base);
  62         nr_pages = host_s2_pgtable_pages();
  63         ret = hyp_pool_init(&host_s2_pool, pfn, nr_pages, 0);
  64         if (ret)
  65                 return ret;
  66
  67         host_kvm.mm_ops = (struct kvm_pgtable_mm_ops) {
  68                 .zalloc_pages_exact = host_s2_zalloc_pages_exact,
  69                 .zalloc_page = host_s2_zalloc_page,
  70                 .phys_to_virt = hyp_phys_to_virt,
  71                 .virt_to_phys = hyp_virt_to_phys,
  72                 .page_count = hyp_page_count,
  73                 .get_page = host_s2_get_page,
  74                 .put_page = host_s2_put_page,
  75         };
  76
  77         return 0;
  78 }
  79
  80 static void prepare_host_vtcr(void)
  81 {
  82         u32 parange, phys_shift;
  83
  84         /* The host stage 2 is id-mapped, so use parange for T0SZ */
  85         parange = kvm_get_parange(id_aa64mmfr0_el1_sys_val);
  86         phys_shift = id_aa64mmfr0_parange_to_phys_shift(parange);
  87
  88         host_kvm.arch.vtcr = kvm_get_vtcr(id_aa64mmfr0_el1_sys_val,
  89                                           id_aa64mmfr1_el1_sys_val, phys_shift);
  90 }
  91
  92 int kvm_host_prepare_stage2(void *pgt_pool_base)
  93 {
  94         struct kvm_s2_mmu *mmu = &host_kvm.arch.mmu;
  95         int ret;
  96
  97         prepare_host_vtcr();
  98         hyp_spin_lock_init(&host_kvm.lock);
  99
 100         ret = prepare_s2_pool(pgt_pool_base);
 101         if (ret)
 102                 return ret;
 103
 104         ret = kvm_pgtable_stage2_init_flags(&host_kvm.pgt, &host_kvm.arch,
 105                                             &host_kvm.mm_ops, KVM_HOST_S2_FLAGS);
 106         if (ret)
 107                 return ret;
 108
 109         mmu->pgd_phys = __hyp_pa(host_kvm.pgt.pgd);
 110         mmu->arch = &host_kvm.arch;
 111         mmu->pgt = &host_kvm.pgt;
 112         mmu->vmid.vmid_gen = 0;
 113         mmu->vmid.vmid = 0;
 114
 115         return 0;
 116 }
 117
 118 int __pkvm_prot_finalize(void)
 119 {
 120         struct kvm_s2_mmu *mmu = &host_kvm.arch.mmu;
 121         struct kvm_nvhe_init_params *params = this_cpu_ptr(&kvm_init_params);
 122
 123         params->vttbr = kvm_get_vttbr(mmu);
 124         params->vtcr = host_kvm.arch.vtcr;
 125         params->hcr_el2 |= HCR_VM;
 126         kvm_flush_dcache_to_poc(params, sizeof(*params));
 127
 128         write_sysreg(params->hcr_el2, hcr_el2);
 129         __load_stage2(&host_kvm.arch.mmu, host_kvm.arch.vtcr);
 130
 131         /*
 132          * Make sure to have an ISB before the TLB maintenance below but only
 133          * when __load_stage2() doesn't include one already.
 134          */
 135         asm(ALTERNATIVE("isb", "nop", ARM64_WORKAROUND_SPECULATIVE_AT));
 136
 137         /* Invalidate stale HCR bits that may be cached in TLBs */
 138         __tlbi(vmalls12e1);
 139         dsb(nsh);
 140         isb();
 141
 142         return 0;
 143 }
 144
 145 static int host_stage2_unmap_dev_all(void)
 146 {
 147         struct kvm_pgtable *pgt = &host_kvm.pgt;
 148         struct memblock_region *reg;
 149         u64 addr = 0;
 150         int i, ret;
 151
 152         /* Unmap all non-memory regions to recycle the pages */
 153         for (i = 0; i < hyp_memblock_nr; i++, addr = reg->base + reg->size) {
 154                 reg = &hyp_memory[i];
 155                 ret = kvm_pgtable_stage2_unmap(pgt, addr, reg->base - addr);
 156                 if (ret)
 157                         return ret;
 158         }
 159         return kvm_pgtable_stage2_unmap(pgt, addr, BIT(pgt->ia_bits) - addr);
 160 }
 161
 162 static bool find_mem_range(phys_addr_t addr, struct kvm_mem_range *range)
 163 {
 164         int cur, left = 0, right = hyp_memblock_nr;
 165         struct memblock_region *reg;
 166         phys_addr_t end;
 167
 168         range->start = 0;
 169         range->end = ULONG_MAX;
 170
 171         /* The list of memblock regions is sorted, binary search it */
 172         while (left < right) {
 173                 cur = (left + right) >> 1;
 174                 reg = &hyp_memory[cur];
 175                 end = reg->base + reg->size;
 176                 if (addr < reg->base) {
 177                         right = cur;
 178                         range->end = reg->base;
 179                 } else if (addr >= end) {
 180                         left = cur + 1;
 181                         range->start = end;
 182                 } else {
 183                         range->start = reg->base;
 184                         range->end = end;
 185                         return true;
 186                 }
 187         }
 188
 189         return false;
 190 }
 191
 192 static bool range_is_memory(u64 start, u64 end)
 193 {
 194         struct kvm_mem_range r1, r2;
 195
 196         if (!find_mem_range(start, &r1) || !find_mem_range(end - 1, &r2))
 197                 return false;
 198         if (r1.start != r2.start)
 199                 return false;
 200
 201         return true;
 202 }
 203
 204 static inline int __host_stage2_idmap(u64 start, u64 end,
 205                                       enum kvm_pgtable_prot prot)
 206 {
 207         return kvm_pgtable_stage2_map(&host_kvm.pgt, start, end - start, start,
 208                                       prot, &host_s2_pool);
 209 }
 210
 211 static int host_stage2_idmap(u64 addr)
 212 {
 213         enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W;
 214         struct kvm_mem_range range;
 215         bool is_memory = find_mem_range(addr, &range);
 216         int ret;
 217
 218         if (is_memory)
 219                 prot |= KVM_PGTABLE_PROT_X;
 220
 221         hyp_spin_lock(&host_kvm.lock);
 222         ret = kvm_pgtable_stage2_find_range(&host_kvm.pgt, addr, prot, &range);
 223         if (ret)
 224                 goto unlock;
 225
 226         ret = __host_stage2_idmap(range.start, range.end, prot);
 227         if (ret != -ENOMEM)
 228                 goto unlock;
 229
 230         /*
 231          * The pool has been provided with enough pages to cover all of memory
 232          * with page granularity, but it is difficult to know how much of the
 233          * MMIO range we will need to cover upfront, so we may need to 'recycle'
 234          * the pages if we run out.
 235          */
 236         ret = host_stage2_unmap_dev_all();
 237         if (ret)
 238                 goto unlock;
 239
 240         ret = __host_stage2_idmap(range.start, range.end, prot);
 241
 242 unlock:
 243         hyp_spin_unlock(&host_kvm.lock);
 244
 245         return ret;
 246 }
 247
 248 int __pkvm_mark_hyp(phys_addr_t start, phys_addr_t end)
 249 {
 250         int ret;
 251
 252         /*
 253          * host_stage2_unmap_dev_all() currently relies on MMIO mappings being
 254          * non-persistent, so don't allow changing page ownership in MMIO range.
 255          */
 256         if (!range_is_memory(start, end))
 257                 return -EINVAL;
 258
 259         hyp_spin_lock(&host_kvm.lock);
 260         ret = kvm_pgtable_stage2_set_owner(&host_kvm.pgt, start, end - start,
 261                                            &host_s2_pool, pkvm_hyp_id);
 262         hyp_spin_unlock(&host_kvm.lock);
 263
 264         return ret != -EAGAIN ? ret : 0;
 265 }
 266
 267 void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
 268 {
 269         struct kvm_vcpu_fault_info fault;
 270         u64 esr, addr;
 271         int ret = 0;
 272
 273         esr = read_sysreg_el2(SYS_ESR);
 274         BUG_ON(!__get_fault_info(esr, &fault));
 275
 276         addr = (fault.hpfar_el2 & HPFAR_MASK) << 8;
 277         ret = host_stage2_idmap(addr);
 278         BUG_ON(ret && ret != -EAGAIN);
 279 }