drivers/xen/mem-reservation.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 /******************************************************************************
   4  * Xen memory reservation utilities.
   5  *
   6  * Copyright (c) 2003, B Dragovic
   7  * Copyright (c) 2003-2004, M Williamson, K Fraser
   8  * Copyright (c) 2005 Dan M. Smith, IBM Corporation
   9  * Copyright (c) 2010 Daniel Kiper
  10  * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
  11  */
  12
  13 #include <asm/xen/hypercall.h>
  14
  15 #include <xen/interface/memory.h>
  16 #include <xen/mem-reservation.h>
  17
  18 /*
  19  * Use one extent per PAGE_SIZE to avoid to break down the page into
  20  * multiple frame.
  21  */
  22 #define EXTENT_ORDER (fls(XEN_PFN_PER_PAGE) - 1)
  23
  24 #ifdef CONFIG_XEN_HAVE_PVMMU
  25 void __xenmem_reservation_va_mapping_update(unsigned long count,
  26                                             struct page **pages,
  27                                             xen_pfn_t *frames)
  28 {
  29         int i;
  30
  31         for (i = 0; i < count; i++) {
  32                 struct page *page = pages[i];
  33                 unsigned long pfn = page_to_pfn(page);
  34
  35                 BUG_ON(!page);
  36
  37                 /*
  38                  * We don't support PV MMU when Linux and Xen is using
  39                  * different page granularity.
  40                  */
  41                 BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
  42
  43                 set_phys_to_machine(pfn, frames[i]);
  44
  45                 /* Link back into the page tables if not highmem. */
  46                 if (!PageHighMem(page)) {
  47                         int ret;
  48
  49                         ret = HYPERVISOR_update_va_mapping(
  50                                         (unsigned long)__va(pfn << PAGE_SHIFT),
  51                                         mfn_pte(frames[i], PAGE_KERNEL),
  52                                         0);
  53                         BUG_ON(ret);
  54                 }
  55         }
  56 }
  57 EXPORT_SYMBOL_GPL(__xenmem_reservation_va_mapping_update);
  58
  59 void __xenmem_reservation_va_mapping_reset(unsigned long count,
  60                                            struct page **pages)
  61 {
  62         int i;
  63
  64         for (i = 0; i < count; i++) {
  65                 struct page *page = pages[i];
  66                 unsigned long pfn = page_to_pfn(page);
  67
  68                 /*
  69                  * We don't support PV MMU when Linux and Xen are using
  70                  * different page granularity.
  71                  */
  72                 BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
  73
  74                 if (!PageHighMem(page)) {
  75                         int ret;
  76
  77                         ret = HYPERVISOR_update_va_mapping(
  78                                         (unsigned long)__va(pfn << PAGE_SHIFT),
  79                                         __pte_ma(0), 0);
  80                         BUG_ON(ret);
  81                 }
  82                 __set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
  83         }
  84 }
  85 EXPORT_SYMBOL_GPL(__xenmem_reservation_va_mapping_reset);
  86 #endif /* CONFIG_XEN_HAVE_PVMMU */
  87
  88 /* @frames is an array of PFNs */
  89 int xenmem_reservation_increase(int count, xen_pfn_t *frames)
  90 {
  91         struct xen_memory_reservation reservation = {
  92                 .address_bits = 0,
  93                 .extent_order = EXTENT_ORDER,
  94                 .domid        = DOMID_SELF
  95         };
  96
  97         /* XENMEM_populate_physmap requires a PFN based on Xen granularity. */
  98         set_xen_guest_handle(reservation.extent_start, frames);
  99         reservation.nr_extents = count;
 100         return HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
 101 }
 102 EXPORT_SYMBOL_GPL(xenmem_reservation_increase);
 103
 104 /* @frames is an array of GFNs */
 105 int xenmem_reservation_decrease(int count, xen_pfn_t *frames)
 106 {
 107         struct xen_memory_reservation reservation = {
 108                 .address_bits = 0,
 109                 .extent_order = EXTENT_ORDER,
 110                 .domid        = DOMID_SELF
 111         };
 112
 113         /* XENMEM_decrease_reservation requires a GFN */
 114         set_xen_guest_handle(reservation.extent_start, frames);
 115         reservation.nr_extents = count;
 116         return HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
 117 }
 118 EXPORT_SYMBOL_GPL(xenmem_reservation_decrease);