arch/arm64/kvm/pkvm.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2020 - Google LLC
   4  * Author: Quentin Perret <qperret@google.com>
   5  */
   6
   7 #include <linux/kvm_host.h>
   8 #include <linux/memblock.h>
   9 #include <linux/sort.h>
  10
  11 #include <asm/kvm_pkvm.h>
  12
  13 #include "hyp_constants.h"
  14
  15 static struct memblock_region *hyp_memory = kvm_nvhe_sym(hyp_memory);
  16 static unsigned int *hyp_memblock_nr_ptr = &kvm_nvhe_sym(hyp_memblock_nr);
  17
  18 phys_addr_t hyp_mem_base;
  19 phys_addr_t hyp_mem_size;
  20
  21 static int cmp_hyp_memblock(const void *p1, const void *p2)
  22 {
  23         const struct memblock_region *r1 = p1;
  24         const struct memblock_region *r2 = p2;
  25
  26         return r1->base < r2->base ? -1 : (r1->base > r2->base);
  27 }
  28
  29 static void __init sort_memblock_regions(void)
  30 {
  31         sort(hyp_memory,
  32              *hyp_memblock_nr_ptr,
  33              sizeof(struct memblock_region),
  34              cmp_hyp_memblock,
  35              NULL);
  36 }
  37
  38 static int __init register_memblock_regions(void)
  39 {
  40         struct memblock_region *reg;
  41
  42         for_each_mem_region(reg) {
  43                 if (*hyp_memblock_nr_ptr >= HYP_MEMBLOCK_REGIONS)
  44                         return -ENOMEM;
  45
  46                 hyp_memory[*hyp_memblock_nr_ptr] = *reg;
  47                 (*hyp_memblock_nr_ptr)++;
  48         }
  49         sort_memblock_regions();
  50
  51         return 0;
  52 }
  53
  54 void __init kvm_hyp_reserve(void)
  55 {
  56         u64 nr_pages, prev, hyp_mem_pages = 0;
  57         int ret;
  58
  59         if (!is_hyp_mode_available() || is_kernel_in_hyp_mode())
  60                 return;
  61
  62         if (kvm_get_mode() != KVM_MODE_PROTECTED)
  63                 return;
  64
  65         ret = register_memblock_regions();
  66         if (ret) {
  67                 *hyp_memblock_nr_ptr = 0;
  68                 kvm_err("Failed to register hyp memblocks: %d\n", ret);
  69                 return;
  70         }
  71
  72         hyp_mem_pages += hyp_s1_pgtable_pages();
  73         hyp_mem_pages += host_s2_pgtable_pages();
  74
  75         /*
  76          * The hyp_vmemmap needs to be backed by pages, but these pages
  77          * themselves need to be present in the vmemmap, so compute the number
  78          * of pages needed by looking for a fixed point.
  79          */
  80         nr_pages = 0;
  81         do {
  82                 prev = nr_pages;
  83                 nr_pages = hyp_mem_pages + prev;
  84                 nr_pages = DIV_ROUND_UP(nr_pages * STRUCT_HYP_PAGE_SIZE,
  85                                         PAGE_SIZE);
  86                 nr_pages += __hyp_pgtable_max_pages(nr_pages);
  87         } while (nr_pages != prev);
  88         hyp_mem_pages += nr_pages;
  89
  90         /*
  91          * Try to allocate a PMD-aligned region to reduce TLB pressure once
  92          * this is unmapped from the host stage-2, and fallback to PAGE_SIZE.
  93          */
  94         hyp_mem_size = hyp_mem_pages << PAGE_SHIFT;
  95         hyp_mem_base = memblock_phys_alloc(ALIGN(hyp_mem_size, PMD_SIZE),
  96                                            PMD_SIZE);
  97         if (!hyp_mem_base)
  98                 hyp_mem_base = memblock_phys_alloc(hyp_mem_size, PAGE_SIZE);
  99         else
 100                 hyp_mem_size = ALIGN(hyp_mem_size, PMD_SIZE);
 101
 102         if (!hyp_mem_base) {
 103                 kvm_err("Failed to reserve hyp memory\n");
 104                 return;
 105         }
 106
 107         kvm_info("Reserved %lld MiB at 0x%llx\n", hyp_mem_size >> 20,
 108                  hyp_mem_base);
 109 }