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Commit a171ce6e authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge
Browse files

xen: dynamically allocate p2m space 



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

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
parent 5e941c09

arch/x86/xen/mmu.c

+22 −8
Original line number Diff line number Diff line
@@ -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);