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);