// SPDX-License-Identifier: GPL-2.0

/******************************************************************************
 * Xen memory reservation utilities.
 *
 * Copyright (c) 2003, B Dragovic
 * Copyright (c) 2003-2004, M Williamson, K Fraser
 * Copyright (c) 2005 Dan M. Smith, IBM Corporation
 * Copyright (c) 2010 Daniel Kiper
 * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
 */

#include <asm/xen/hypercall.h>

#include <xen/interface/memory.h>
#include <xen/mem-reservation.h>
#include <linux/moduleparam.h>

bool __read_mostly xen_scrub_pages = IS_ENABLED(CONFIG_XEN_SCRUB_PAGES_DEFAULT);
core_param(xen_scrub_pages, xen_scrub_pages, bool, 0);

/*
 * Use one extent per PAGE_SIZE to avoid to break down the page into
 * multiple frame.
 */
#define EXTENT_ORDER (fls(XEN_PFN_PER_PAGE) - 1)

#ifdef CONFIG_XEN_HAVE_PVMMU
void __xenmem_reservation_va_mapping_update(unsigned long count,
                                            struct page **pages,
                                            xen_pfn_t *frames)
{
        int i;

        for (i = 0; i < count; i++) {
                struct page *page = pages[i];
                unsigned long pfn = page_to_pfn(page);
                int ret;

                BUG_ON(!page);

                /*
                 * We don't support PV MMU when Linux and Xen is using
                 * different page granularity.
                 */
                BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);

                set_phys_to_machine(pfn, frames[i]);

                ret = HYPERVISOR_update_va_mapping(
                                (unsigned long)__va(pfn << PAGE_SHIFT),
                                mfn_pte(frames[i], PAGE_KERNEL), 0);
                BUG_ON(ret);
        }
}
EXPORT_SYMBOL_GPL(__xenmem_reservation_va_mapping_update);

void __xenmem_reservation_va_mapping_reset(unsigned long count,
                                           struct page **pages)
{
        int i;

        for (i = 0; i < count; i++) {
                struct page *page = pages[i];
                unsigned long pfn = page_to_pfn(page);
                int ret;

                /*
                 * We don't support PV MMU when Linux and Xen are using
                 * different page granularity.
                 */
                BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);

                ret = HYPERVISOR_update_va_mapping(
                                (unsigned long)__va(pfn << PAGE_SHIFT),
                                __pte_ma(0), 0);
                BUG_ON(ret);

                __set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
        }
}
EXPORT_SYMBOL_GPL(__xenmem_reservation_va_mapping_reset);
#endif /* CONFIG_XEN_HAVE_PVMMU */

/* @frames is an array of PFNs */
int xenmem_reservation_increase(int count, xen_pfn_t *frames)
{
        struct xen_memory_reservation reservation = {
                .address_bits = 0,
                .extent_order = EXTENT_ORDER,
                .domid        = DOMID_SELF
        };

        /* XENMEM_populate_physmap requires a PFN based on Xen granularity. */
        set_xen_guest_handle(reservation.extent_start, frames);
        reservation.nr_extents = count;
        return HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
}
EXPORT_SYMBOL_GPL(xenmem_reservation_increase);

/* @frames is an array of GFNs */
int xenmem_reservation_decrease(int count, xen_pfn_t *frames)
{
        struct xen_memory_reservation reservation = {
                .address_bits = 0,
                .extent_order = EXTENT_ORDER,
                .domid        = DOMID_SELF
        };

        /* XENMEM_decrease_reservation requires a GFN */
        set_xen_guest_handle(reservation.extent_start, frames);
        reservation.nr_extents = count;
        return HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
}
EXPORT_SYMBOL_GPL(xenmem_reservation_decrease);