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xen: dynamically allocate p2m space

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Use early brk mechanism to allocate p2m tables, to save memory when
booting non-Xen.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
This commit is contained in:
Jeremy Fitzhardinge 2010-08-26 15:04:48 -07:00
parent 5e941c0939
commit a171ce6e7b
1 changed files with 22 additions and 8 deletions
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30
arch/x86/xen/mmu.c
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@ -174,18 +174,16 @@ DEFINE_PER_CPU(unsigned long, xen_current_cr3); /* actual vcpu cr3 */
#define TOP_ENTRIES (MAX_DOMAIN_PAGES / P2M_ENTRIES_PER_PAGE)
/* Placeholder for holes in the address space */
static unsigned long p2m_missing[P2M_ENTRIES_PER_PAGE] __page_aligned_data =
{ [ 0 ... P2M_ENTRIES_PER_PAGE-1 ] = ~0UL };
static RESERVE_BRK_ARRAY(unsigned long, p2m_missing, P2M_ENTRIES_PER_PAGE);
/* Array of pointers to pages containing p2m entries */
static unsigned long *p2m_top[TOP_ENTRIES] __page_aligned_data =
{ [ 0 ... TOP_ENTRIES - 1] = &p2m_missing[0] };
static RESERVE_BRK_ARRAY(unsigned long *, p2m_top, TOP_ENTRIES);
/* Arrays of p2m arrays expressed in mfns used for save/restore */
static unsigned long p2m_top_mfn[TOP_ENTRIES] __page_aligned_bss;
static RESERVE_BRK_ARRAY(unsigned long, p2m_top_mfn, TOP_ENTRIES);
static unsigned long p2m_top_mfn_list[TOP_ENTRIES / P2M_ENTRIES_PER_PAGE]
__page_aligned_bss;
static RESERVE_BRK_ARRAY(unsigned long, p2m_top_mfn_list,
(TOP_ENTRIES / P2M_ENTRIES_PER_PAGE));
static inline unsigned p2m_top_index(unsigned long pfn)
{
@ -209,7 +207,7 @@ void xen_build_mfn_list_list(void)
p2m_top_mfn[topidx] = virt_to_mfn(p2m_top[topidx]);
}
for (idx = 0; idx < ARRAY_SIZE(p2m_top_mfn_list); idx++) {
for (idx = 0; idx < TOP_ENTRIES/P2M_ENTRIES_PER_PAGE; idx++) {
unsigned topidx = idx * P2M_ENTRIES_PER_PAGE;
p2m_top_mfn_list[idx] = virt_to_mfn(&p2m_top_mfn[topidx]);
}
@ -230,6 +228,22 @@ void __init xen_build_dynamic_phys_to_machine(void)
unsigned long *mfn_list = (unsigned long *)xen_start_info->mfn_list;
unsigned long max_pfn = min(MAX_DOMAIN_PAGES, xen_start_info->nr_pages);
unsigned pfn;
unsigned i;
p2m_missing = extend_brk(sizeof(*p2m_missing) * P2M_ENTRIES_PER_PAGE,
PAGE_SIZE);
for (i = 0; i < P2M_ENTRIES_PER_PAGE; i++)
p2m_missing[i] = ~0UL;
p2m_top = extend_brk(sizeof(*p2m_top) * TOP_ENTRIES,
PAGE_SIZE);
for (i = 0; i < TOP_ENTRIES; i++)
p2m_top[i] = p2m_missing;
p2m_top_mfn = extend_brk(sizeof(*p2m_top_mfn) * TOP_ENTRIES, PAGE_SIZE);
p2m_top_mfn_list = extend_brk(sizeof(*p2m_top_mfn_list) *
(TOP_ENTRIES / P2M_ENTRIES_PER_PAGE),
PAGE_SIZE);
for (pfn = 0; pfn < max_pfn; pfn += P2M_ENTRIES_PER_PAGE) {
unsigned topidx = p2m_top_index(pfn);