LXR linux/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
  19bool __read_mostly xen_scrub_pages = IS_ENABLED(CONFIG_XEN_SCRUB_PAGES_DEFAULT);
  20core_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
  29void __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
  39                BUG_ON(!page);
  40
  41                /*
  42                 * We don't support PV MMU when Linux and Xen is using
  43                 * different page granularity.
  44                 */
  45                BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
  46
  47                set_phys_to_machine(pfn, frames[i]);
  48
  49                /* Link back into the page tables if not highmem. */
  50                if (!PageHighMem(page)) {
  51                        int ret;
  52
  53                        ret = HYPERVISOR_update_va_mapping(
  54                                        (unsigned long)__va(pfn << PAGE_SHIFT),
  55                                        mfn_pte(frames[i], PAGE_KERNEL),
  56                                        0);
  57                        BUG_ON(ret);
  58                }
  59        }
  60}
  61EXPORT_SYMBOL_GPL(__xenmem_reservation_va_mapping_update);
  62
  63void __xenmem_reservation_va_mapping_reset(unsigned long count,
  64                                           struct page **pages)
  65{
  66        int i;
  67
  68        for (i = 0; i < count; i++) {
  69                struct page *page = pages[i];
  70                unsigned long pfn = page_to_pfn(page);
  71
  72                /*
  73                 * We don't support PV MMU when Linux and Xen are using
  74                 * different page granularity.
  75                 */
  76                BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
  77
  78                if (!PageHighMem(page)) {
  79                        int ret;
  80
  81                        ret = HYPERVISOR_update_va_mapping(
  82                                        (unsigned long)__va(pfn << PAGE_SHIFT),
  83                                        __pte_ma(0), 0);
  84                        BUG_ON(ret);
  85                }
  86                __set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
  87        }
  88}
  89EXPORT_SYMBOL_GPL(__xenmem_reservation_va_mapping_reset);
  90#endif /* CONFIG_XEN_HAVE_PVMMU */
  91
  92/* @frames is an array of PFNs */
  93int xenmem_reservation_increase(int count, xen_pfn_t *frames)
  94{
  95        struct xen_memory_reservation reservation = {
  96                .address_bits = 0,
  97                .extent_order = EXTENT_ORDER,
  98                .domid        = DOMID_SELF
  99        };
 100
 101        /* XENMEM_populate_physmap requires a PFN based on Xen granularity. */
 102        set_xen_guest_handle(reservation.extent_start, frames);
 103        reservation.nr_extents = count;
 104        return HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
 105}
 106EXPORT_SYMBOL_GPL(xenmem_reservation_increase);
 107
 108/* @frames is an array of GFNs */
 109int xenmem_reservation_decrease(int count, xen_pfn_t *frames)
 110{
 111        struct xen_memory_reservation reservation = {
 112                .address_bits = 0,
 113                .extent_order = EXTENT_ORDER,
 114                .domid        = DOMID_SELF
 115        };
 116
 117        /* XENMEM_decrease_reservation requires a GFN */
 118        set_xen_guest_handle(reservation.extent_start, frames);
 119        reservation.nr_extents = count;
 120        return HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
 121}
 122EXPORT_SYMBOL_GPL(xenmem_reservation_decrease);
 123