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 #include <linux/moduleparam.h>
  18
  19 bool __read_mostly xen_scrub_pages = IS_ENABLED(CONFIG_XEN_SCRUB_PAGES_DEFAULT);
  20 core_param(xen_scrub_pages, xen_scrub_pages, bool, 0);
  21
  22 /*
  23  * Use one extent per PAGE_SIZE to avoid to break down the page into
  24  * multiple frame.
  25  */
  26 #define EXTENT_ORDER (fls(XEN_PFN_PER_PAGE) - 1)
  27
  28 #ifdef CONFIG_XEN_HAVE_PVMMU
  29 void __xenmem_reservation_va_mapping_update(unsigned long count,
  30                                             struct page **pages,
  31                                             xen_pfn_t *frames)
  32 {
  33         int i;
  34
  35         for (i = 0; i < count; i++) {
  36                 struct page *page = pages[i];
  37                 unsigned long pfn = page_to_pfn(page);
  38                 int ret;
  39
  40                 BUG_ON(!page);
  41
  42                 /*
  43                  * We don't support PV MMU when Linux and Xen is using
  44                  * different page granularity.
  45                  */
  46                 BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
  47
  48                 set_phys_to_machine(pfn, frames[i]);
  49
  50                 ret = HYPERVISOR_update_va_mapping(
  51                                 (unsigned long)__va(pfn << PAGE_SHIFT),
  52                                 mfn_pte(frames[i], PAGE_KERNEL), 0);
  53                 BUG_ON(ret);
  54         }
  55 }
  56 EXPORT_SYMBOL_GPL(__xenmem_reservation_va_mapping_update);
  57
  58 void __xenmem_reservation_va_mapping_reset(unsigned long count,
  59                                            struct page **pages)
  60 {
  61         int i;
  62
  63         for (i = 0; i < count; i++) {
  64                 struct page *page = pages[i];
  65                 unsigned long pfn = page_to_pfn(page);
  66                 int ret;
  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                 ret = HYPERVISOR_update_va_mapping(
  75                                 (unsigned long)__va(pfn << PAGE_SHIFT),
  76                                 __pte_ma(0), 0);
  77                 BUG_ON(ret);
  78
  79                 __set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
  80         }
  81 }
  82 EXPORT_SYMBOL_GPL(__xenmem_reservation_va_mapping_reset);
  83 #endif /* CONFIG_XEN_HAVE_PVMMU */
  84
  85 /* @frames is an array of PFNs */
  86 int xenmem_reservation_increase(int count, xen_pfn_t *frames)
  87 {
  88         struct xen_memory_reservation reservation = {
  89                 .address_bits = 0,
  90                 .extent_order = EXTENT_ORDER,
  91                 .domid        = DOMID_SELF
  92         };
  93
  94         /* XENMEM_populate_physmap requires a PFN based on Xen granularity. */
  95         set_xen_guest_handle(reservation.extent_start, frames);
  96         reservation.nr_extents = count;
  97         return HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
  98 }
  99 EXPORT_SYMBOL_GPL(xenmem_reservation_increase);
 100
 101 /* @frames is an array of GFNs */
 102 int xenmem_reservation_decrease(int count, xen_pfn_t *frames)
 103 {
 104         struct xen_memory_reservation reservation = {
 105                 .address_bits = 0,
 106                 .extent_order = EXTENT_ORDER,
 107                 .domid        = DOMID_SELF
 108         };
 109
 110         /* XENMEM_decrease_reservation requires a GFN */
 111         set_xen_guest_handle(reservation.extent_start, frames);
 112         reservation.nr_extents = count;
 113         return HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
 114 }
 115 EXPORT_SYMBOL_GPL(xenmem_reservation_decrease);