/*
* This function takes a contiguous pfn range that needs to be identity mapped
* and:
*
* 1) Finds a new range of pfns to use to remap based on E820 and remap_pfn.
* 2) Calls the do_ function to actually do the mapping/remapping work.
*
* The goal is to not allocate additional memory but to remap the existing
* pages. In the case of an error the underlying memory is simply released back
* to Xen and not remapped.
*/
static unsigned long __init xen_set_identity_and_remap_chunk(
unsigned long start_pfn, unsigned long end_pfn, unsigned long nr_pages,
unsigned long remap_pfn)
{
unsigned long pfn;
unsigned long i = 0;
unsigned long n = end_pfn - start_pfn;
if (remap_pfn == 0)
remap_pfn = nr_pages;
while (i < n) {
unsigned long cur_pfn = start_pfn + i;
unsigned long left = n - i;
unsigned long size = left;
unsigned long remap_range_size;
/* Do not remap pages beyond the current allocation */
if (cur_pfn >= nr_pages) {
/* Identity map remaining pages */
set_phys_range_identity(cur_pfn, cur_pfn + size);
break;
}
if (cur_pfn + size > nr_pages)
size = nr_pages - cur_pfn;
remap_range_size = xen_find_pfn_range(&remap_pfn);
if (!remap_range_size) {
pr_warning("Unable to find available pfn range, not remapping identity pages\n");
xen_set_identity_and_release_chunk(cur_pfn,
cur_pfn + left, nr_pages);
break;
}
/* Adjust size to fit in current e820 RAM region */
if (size > remap_range_size)
size = remap_range_size;
xen_do_set_identity_and_remap_chunk(cur_pfn, size, remap_pfn);
/* Update variables to reflect new mappings. */
i += size;
remap_pfn += size;
}
/*
* If the PFNs are currently mapped, the VA mapping also needs
* to be updated to be 1:1.
*/
for (pfn = start_pfn; pfn <= max_pfn_mapped && pfn < end_pfn; pfn++)
(void)HYPERVISOR_update_va_mapping(
(unsigned long)__va(pfn << PAGE_SHIFT),
mfn_pte(pfn, PAGE_KERNEL_IO), 0);
return remap_pfn;
}
static unsigned long __init xen_set_identity_and_release(
const struct e820entry *list, size_t map_size, unsigned long nr_pages)
{
phys_addr_t start = 0;
unsigned long released = 0;
unsigned long identity = 0;
const struct e820entry *entry;
int i;
int xlated_phys = xen_feature(XENFEAT_auto_translated_physmap);
/*
* Combine non-RAM regions and gaps until a RAM region (or the
* end of the map) is reached, then set the 1:1 map and
* release the pages (if available) in those non-RAM regions.
*
* The combined non-RAM regions are rounded to a whole number
* of pages so any partial pages are accessible via the 1:1
* mapping. This is needed for some BIOSes that put (for
* example) the DMI tables in a reserved region that begins on
* a non-page boundary.
*/
for (i = 0, entry = list; i < map_size; i++, entry++) {
phys_addr_t end = entry->addr + entry->size;
if (entry->type == E820_RAM || i == map_size - 1) {
unsigned long start_pfn = PFN_DOWN(start);
unsigned long end_pfn = PFN_UP(end);
if (entry->type == E820_RAM)
end_pfn = PFN_UP(entry->addr);
if (start_pfn < end_pfn) {
if (xlated_phys) {
xen_pvh_adjust_stats(start_pfn,
end_pfn, &released, &identity,
nr_pages);
} else {
xen_set_identity_and_release_chunk(
start_pfn, end_pfn, nr_pages,
&released, &identity);
}
}
start = end;
}
}
if (released)
printk(KERN_INFO "Released %lu pages of unused memory\n", released);
if (identity)
printk(KERN_INFO "Set %ld page(s) to 1-1 mapping\n", identity);
return released;
}
