arch/arm64/kvm/pkvm.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2020 - Google LLC
   4  * Author: Quentin Perret <[email protected]>
   5  */
   6
   7 #include <linux/init.h>
   8 #include <linux/kmemleak.h>
   9 #include <linux/kvm_host.h>
  10 #include <linux/memblock.h>
  11 #include <linux/mutex.h>
  12 #include <linux/sort.h>
  13
  14 #include <asm/kvm_pkvm.h>
  15
  16 #include "hyp_constants.h"
  17
  18 DEFINE_STATIC_KEY_FALSE(kvm_protected_mode_initialized);
  19
  20 static struct memblock_region *hyp_memory = kvm_nvhe_sym(hyp_memory);
  21 static unsigned int *hyp_memblock_nr_ptr = &kvm_nvhe_sym(hyp_memblock_nr);
  22
  23 phys_addr_t hyp_mem_base;
  24 phys_addr_t hyp_mem_size;
  25
  26 static int cmp_hyp_memblock(const void *p1, const void *p2)
  27 {
  28         const struct memblock_region *r1 = p1;
  29         const struct memblock_region *r2 = p2;
  30
  31         return r1->base < r2->base ? -1 : (r1->base > r2->base);
  32 }
  33
  34 static void __init sort_memblock_regions(void)
  35 {
  36         sort(hyp_memory,
  37              *hyp_memblock_nr_ptr,
  38              sizeof(struct memblock_region),
  39              cmp_hyp_memblock,
  40              NULL);
  41 }
  42
  43 static int __init register_memblock_regions(void)
  44 {
  45         struct memblock_region *reg;
  46
  47         for_each_mem_region(reg) {
  48                 if (*hyp_memblock_nr_ptr >= HYP_MEMBLOCK_REGIONS)
  49                         return -ENOMEM;
  50
  51                 hyp_memory[*hyp_memblock_nr_ptr] = *reg;
  52                 (*hyp_memblock_nr_ptr)++;
  53         }
  54         sort_memblock_regions();
  55
  56         return 0;
  57 }
  58
  59 void __init kvm_hyp_reserve(void)
  60 {
  61         u64 hyp_mem_pages = 0;
  62         int ret;
  63
  64         if (!is_hyp_mode_available() || is_kernel_in_hyp_mode())
  65                 return;
  66
  67         if (kvm_get_mode() != KVM_MODE_PROTECTED)
  68                 return;
  69
  70         ret = register_memblock_regions();
  71         if (ret) {
  72                 *hyp_memblock_nr_ptr = 0;
  73                 kvm_err("Failed to register hyp memblocks: %d\n", ret);
  74                 return;
  75         }
  76
  77         hyp_mem_pages += hyp_s1_pgtable_pages();
  78         hyp_mem_pages += host_s2_pgtable_pages();
  79         hyp_mem_pages += hyp_vm_table_pages();
  80         hyp_mem_pages += hyp_vmemmap_pages(STRUCT_HYP_PAGE_SIZE);
  81
  82         /*
  83          * Try to allocate a PMD-aligned region to reduce TLB pressure once
  84          * this is unmapped from the host stage-2, and fallback to PAGE_SIZE.
  85          */
  86         hyp_mem_size = hyp_mem_pages << PAGE_SHIFT;
  87         hyp_mem_base = memblock_phys_alloc(ALIGN(hyp_mem_size, PMD_SIZE),
  88                                            PMD_SIZE);
  89         if (!hyp_mem_base)
  90                 hyp_mem_base = memblock_phys_alloc(hyp_mem_size, PAGE_SIZE);
  91         else
  92                 hyp_mem_size = ALIGN(hyp_mem_size, PMD_SIZE);
  93
  94         if (!hyp_mem_base) {
  95                 kvm_err("Failed to reserve hyp memory\n");
  96                 return;
  97         }
  98
  99         kvm_info("Reserved %lld MiB at 0x%llx\n", hyp_mem_size >> 20,
 100                  hyp_mem_base);
 101 }
 102
 103 /*
 104  * Allocates and donates memory for hypervisor VM structs at EL2.
 105  *
 106  * Allocates space for the VM state, which includes the hyp vm as well as
 107  * the hyp vcpus.
 108  *
 109  * Stores an opaque handler in the kvm struct for future reference.
 110  *
 111  * Return 0 on success, negative error code on failure.
 112  */
 113 static int __pkvm_create_hyp_vm(struct kvm *host_kvm)
 114 {
 115         size_t pgd_sz, hyp_vm_sz, hyp_vcpu_sz;
 116         struct kvm_vcpu *host_vcpu;
 117         pkvm_handle_t handle;
 118         void *pgd, *hyp_vm;
 119         unsigned long idx;
 120         int ret;
 121
 122         if (host_kvm->created_vcpus < 1)
 123                 return -EINVAL;
 124
 125         pgd_sz = kvm_pgtable_stage2_pgd_size(host_kvm->arch.vtcr);
 126
 127         /*
 128          * The PGD pages will be reclaimed using a hyp_memcache which implies
 129          * page granularity. So, use alloc_pages_exact() to get individual
 130          * refcounts.
 131          */
 132         pgd = alloc_pages_exact(pgd_sz, GFP_KERNEL_ACCOUNT);
 133         if (!pgd)
 134                 return -ENOMEM;
 135
 136         /* Allocate memory to donate to hyp for vm and vcpu pointers. */
 137         hyp_vm_sz = PAGE_ALIGN(size_add(PKVM_HYP_VM_SIZE,
 138                                         size_mul(sizeof(void *),
 139                                                  host_kvm->created_vcpus)));
 140         hyp_vm = alloc_pages_exact(hyp_vm_sz, GFP_KERNEL_ACCOUNT);
 141         if (!hyp_vm) {
 142                 ret = -ENOMEM;
 143                 goto free_pgd;
 144         }
 145
 146         /* Donate the VM memory to hyp and let hyp initialize it. */
 147         ret = kvm_call_hyp_nvhe(__pkvm_init_vm, host_kvm, hyp_vm, pgd);
 148         if (ret < 0)
 149                 goto free_vm;
 150
 151         handle = ret;
 152
 153         host_kvm->arch.pkvm.handle = handle;
 154
 155         /* Donate memory for the vcpus at hyp and initialize it. */
 156         hyp_vcpu_sz = PAGE_ALIGN(PKVM_HYP_VCPU_SIZE);
 157         kvm_for_each_vcpu(idx, host_vcpu, host_kvm) {
 158                 void *hyp_vcpu;
 159
 160                 /* Indexing of the vcpus to be sequential starting at 0. */
 161                 if (WARN_ON(host_vcpu->vcpu_idx != idx)) {
 162                         ret = -EINVAL;
 163                         goto destroy_vm;
 164                 }
 165
 166                 hyp_vcpu = alloc_pages_exact(hyp_vcpu_sz, GFP_KERNEL_ACCOUNT);
 167                 if (!hyp_vcpu) {
 168                         ret = -ENOMEM;
 169                         goto destroy_vm;
 170                 }
 171
 172                 ret = kvm_call_hyp_nvhe(__pkvm_init_vcpu, handle, host_vcpu,
 173                                         hyp_vcpu);
 174                 if (ret) {
 175                         free_pages_exact(hyp_vcpu, hyp_vcpu_sz);
 176                         goto destroy_vm;
 177                 }
 178         }
 179
 180         return 0;
 181
 182 destroy_vm:
 183         pkvm_destroy_hyp_vm(host_kvm);
 184         return ret;
 185 free_vm:
 186         free_pages_exact(hyp_vm, hyp_vm_sz);
 187 free_pgd:
 188         free_pages_exact(pgd, pgd_sz);
 189         return ret;
 190 }
 191
 192 int pkvm_create_hyp_vm(struct kvm *host_kvm)
 193 {
 194         int ret = 0;
 195
 196         mutex_lock(&host_kvm->lock);
 197         if (!host_kvm->arch.pkvm.handle)
 198                 ret = __pkvm_create_hyp_vm(host_kvm);
 199         mutex_unlock(&host_kvm->lock);
 200
 201         return ret;
 202 }
 203
 204 void pkvm_destroy_hyp_vm(struct kvm *host_kvm)
 205 {
 206         if (host_kvm->arch.pkvm.handle) {
 207                 WARN_ON(kvm_call_hyp_nvhe(__pkvm_teardown_vm,
 208                                           host_kvm->arch.pkvm.handle));
 209         }
 210
 211         host_kvm->arch.pkvm.handle = 0;
 212         free_hyp_memcache(&host_kvm->arch.pkvm.teardown_mc);
 213 }
 214
 215 int pkvm_init_host_vm(struct kvm *host_kvm)
 216 {
 217         mutex_init(&host_kvm->lock);
 218         return 0;
 219 }
 220
 221 static void __init _kvm_host_prot_finalize(void *arg)
 222 {
 223         int *err = arg;
 224
 225         if (WARN_ON(kvm_call_hyp_nvhe(__pkvm_prot_finalize)))
 226                 WRITE_ONCE(*err, -EINVAL);
 227 }
 228
 229 static int __init pkvm_drop_host_privileges(void)
 230 {
 231         int ret = 0;
 232
 233         /*
 234          * Flip the static key upfront as that may no longer be possible
 235          * once the host stage 2 is installed.
 236          */
 237         static_branch_enable(&kvm_protected_mode_initialized);
 238         on_each_cpu(_kvm_host_prot_finalize, &ret, 1);
 239         return ret;
 240 }
 241
 242 static int __init finalize_pkvm(void)
 243 {
 244         int ret;
 245
 246         if (!is_protected_kvm_enabled())
 247                 return 0;
 248
 249         /*
 250          * Exclude HYP sections from kmemleak so that they don't get peeked
 251          * at, which would end badly once inaccessible.
 252          */
 253         kmemleak_free_part(__hyp_bss_start, __hyp_bss_end - __hyp_bss_start);
 254         kmemleak_free_part_phys(hyp_mem_base, hyp_mem_size);
 255
 256         ret = pkvm_drop_host_privileges();
 257         if (ret)
 258                 pr_err("Failed to finalize Hyp protection: %d\n", ret);
 259
 260         return ret;
 261 }
 262 device_initcall_sync(finalize_pkvm);