drivers/xen/mem-reservation.c

0001 // SPDX-License-Identifier: GPL-2.0
0002
0003 /******************************************************************************
0004  * Xen memory reservation utilities.
0005  *
0006  * Copyright (c) 2003, B Dragovic
0007  * Copyright (c) 2003-2004, M Williamson, K Fraser
0008  * Copyright (c) 2005 Dan M. Smith, IBM Corporation
0009  * Copyright (c) 2010 Daniel Kiper
0010  * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
0011  */
0012
0013 #include <asm/xen/hypercall.h>
0014
0015 #include <xen/interface/memory.h>
0016 #include <xen/mem-reservation.h>
0017 #include <linux/moduleparam.h>
0018
0019 bool __read_mostly xen_scrub_pages = IS_ENABLED(CONFIG_XEN_SCRUB_PAGES_DEFAULT);
0020 core_param(xen_scrub_pages, xen_scrub_pages, bool, 0);
0021
0022 /*
0023  * Use one extent per PAGE_SIZE to avoid to break down the page into
0024  * multiple frame.
0025  */
0026 #define EXTENT_ORDER (fls(XEN_PFN_PER_PAGE) - 1)
0027
0028 #ifdef CONFIG_XEN_HAVE_PVMMU
0029 void __xenmem_reservation_va_mapping_update(unsigned long count,
0030                         struct page **pages,
0031                         xen_pfn_t *frames)
0032 {
0033     int i;
0034
0035     for (i = 0; i < count; i++) {
0036         struct page *page = pages[i];
0037         unsigned long pfn = page_to_pfn(page);
0038         int ret;
0039
0040         BUG_ON(!page);
0041
0042         /*
0043          * We don't support PV MMU when Linux and Xen is using
0044          * different page granularity.
0045          */
0046         BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
0047
0048         set_phys_to_machine(pfn, frames[i]);
0049
0050         ret = HYPERVISOR_update_va_mapping(
0051                 (unsigned long)__va(pfn << PAGE_SHIFT),
0052                 mfn_pte(frames[i], PAGE_KERNEL), 0);
0053         BUG_ON(ret);
0054     }
0055 }
0056 EXPORT_SYMBOL_GPL(__xenmem_reservation_va_mapping_update);
0057
0058 void __xenmem_reservation_va_mapping_reset(unsigned long count,
0059                        struct page **pages)
0060 {
0061     int i;
0062
0063     for (i = 0; i < count; i++) {
0064         struct page *page = pages[i];
0065         unsigned long pfn = page_to_pfn(page);
0066         int ret;
0067
0068         /*
0069          * We don't support PV MMU when Linux and Xen are using
0070          * different page granularity.
0071          */
0072         BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
0073
0074         ret = HYPERVISOR_update_va_mapping(
0075                 (unsigned long)__va(pfn << PAGE_SHIFT),
0076                 __pte_ma(0), 0);
0077         BUG_ON(ret);
0078
0079         __set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
0080     }
0081 }
0082 EXPORT_SYMBOL_GPL(__xenmem_reservation_va_mapping_reset);
0083 #endif /* CONFIG_XEN_HAVE_PVMMU */
0084
0085 /* @frames is an array of PFNs */
0086 int xenmem_reservation_increase(int count, xen_pfn_t *frames)
0087 {
0088     struct xen_memory_reservation reservation = {
0089         .address_bits = 0,
0090         .extent_order = EXTENT_ORDER,
0091         .domid        = DOMID_SELF
0092     };
0093
0094     /* XENMEM_populate_physmap requires a PFN based on Xen granularity. */
0095     set_xen_guest_handle(reservation.extent_start, frames);
0096     reservation.nr_extents = count;
0097     return HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
0098 }
0099 EXPORT_SYMBOL_GPL(xenmem_reservation_increase);
0100
0101 /* @frames is an array of GFNs */
0102 int xenmem_reservation_decrease(int count, xen_pfn_t *frames)
0103 {
0104     struct xen_memory_reservation reservation = {
0105         .address_bits = 0,
0106         .extent_order = EXTENT_ORDER,
0107         .domid        = DOMID_SELF
0108     };
0109
0110     /* XENMEM_decrease_reservation requires a GFN */
0111     set_xen_guest_handle(reservation.extent_start, frames);
0112     reservation.nr_extents = count;
0113     return HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
0114 }
0115 EXPORT_SYMBOL_GPL(xenmem_reservation_decrease);