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/* SPDX-License-Identifier: GPL-2.0 */
#include <xen/init.h>
#include <xen/mm.h>
#include <asm/setup.h>
/* Override macros from asm/page.h to make them work with mfn_t */
#undef virt_to_mfn
#define virt_to_mfn(va) _mfn(__virt_to_mfn(va))
static DEFINE_PAGE_TABLE(xen_first_id);
static DEFINE_PAGE_TABLE(xen_second_id);
static DEFINE_PAGE_TABLE(xen_third_id);
/*
* The identity mapping may start at physical address 0. So we don't want
* to keep it mapped longer than necessary.
*
* When this is called, we are still using the boot_pgtable.
*
* We need to prepare the identity mapping for both the boot page tables
* and runtime page tables.
*
* The logic to create the entry is slightly different because Xen may
* be running at a different location at runtime.
*/
static void __init prepare_boot_identity_mapping(void)
{
paddr_t id_addr = virt_to_maddr(_start);
lpae_t pte;
DECLARE_OFFSETS(id_offsets, id_addr);
/*
* We will be re-using the boot ID tables. They may not have been
* zeroed but they should be unlinked. So it is fine to use
* clear_page().
*/
clear_page(boot_first_id);
clear_page(boot_second_id);
clear_page(boot_third_id);
if ( id_offsets[0] >= IDENTITY_MAPPING_AREA_NR_L0 )
panic("Cannot handle ID mapping above 2TB\n");
/* Link first ID table */
pte = mfn_to_xen_entry(virt_to_mfn(boot_first_id), MT_NORMAL);
pte.pt.table = 1;
pte.pt.xn = 0;
write_pte(&boot_pgtable[id_offsets[0]], pte);
/* Link second ID table */
pte = mfn_to_xen_entry(virt_to_mfn(boot_second_id), MT_NORMAL);
pte.pt.table = 1;
pte.pt.xn = 0;
write_pte(&boot_first_id[id_offsets[1]], pte);
/* Link third ID table */
pte = mfn_to_xen_entry(virt_to_mfn(boot_third_id), MT_NORMAL);
pte.pt.table = 1;
pte.pt.xn = 0;
write_pte(&boot_second_id[id_offsets[2]], pte);
/* The mapping in the third table will be created at a later stage */
}
static void __init prepare_runtime_identity_mapping(void)
{
paddr_t id_addr = virt_to_maddr(_start);
lpae_t pte;
DECLARE_OFFSETS(id_offsets, id_addr);
if ( id_offsets[0] >= IDENTITY_MAPPING_AREA_NR_L0 )
panic("Cannot handle ID mapping above 2TB\n");
/* Link first ID table */
pte = pte_of_xenaddr((vaddr_t)xen_first_id);
pte.pt.table = 1;
pte.pt.xn = 0;
write_pte(&xen_pgtable[id_offsets[0]], pte);
/* Link second ID table */
pte = pte_of_xenaddr((vaddr_t)xen_second_id);
pte.pt.table = 1;
pte.pt.xn = 0;
write_pte(&xen_first_id[id_offsets[1]], pte);
/* Link third ID table */
pte = pte_of_xenaddr((vaddr_t)xen_third_id);
pte.pt.table = 1;
pte.pt.xn = 0;
write_pte(&xen_second_id[id_offsets[2]], pte);
/* The mapping in the third table will be created at a later stage */
}
void __init arch_setup_page_tables(void)
{
prepare_boot_identity_mapping();
prepare_runtime_identity_mapping();
}
void update_identity_mapping(bool enable)
{
paddr_t id_addr = virt_to_maddr(_start);
int rc;
if ( enable )
rc = map_pages_to_xen(id_addr, maddr_to_mfn(id_addr), 1,
PAGE_HYPERVISOR_RX);
else
rc = destroy_xen_mappings(id_addr, id_addr + PAGE_SIZE);
BUG_ON(rc);
}
extern void switch_ttbr_id(uint64_t ttbr);
typedef void (switch_ttbr_fn)(uint64_t ttbr);
void __init switch_ttbr(uint64_t ttbr)
{
vaddr_t id_addr = virt_to_maddr(switch_ttbr_id);
switch_ttbr_fn *fn = (switch_ttbr_fn *)id_addr;
lpae_t pte;
/* Enable the identity mapping in the boot page tables */
update_identity_mapping(true);
/* Enable the identity mapping in the runtime page tables */
pte = pte_of_xenaddr((vaddr_t)switch_ttbr_id);
pte.pt.table = 1;
pte.pt.xn = 0;
pte.pt.ro = 1;
write_pte(&xen_third_id[third_table_offset(id_addr)], pte);
/* Switch TTBR */
fn(ttbr);
/*
* Disable the identity mapping in the runtime page tables.
* Note it is not necessary to disable it in the boot page tables
* because they are not going to be used by this CPU anymore.
*/
update_identity_mapping(false);
}
/*
* Local variables:
* mode: C
* c-file-style: "BSD"
* c-basic-offset: 4
* indent-tabs-mode: nil
* End:
*/
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