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xen: make phys_to_machine structure dynamic

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We now support the use of memory hotplug, so the physical to machine
page mapping structure must be dynamic.  This is implemented as a
two-level radix tree structure, which allows us to efficiently
incrementally allocate memory for the p2m table as new pages are
added.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Jeremy Fitzhardinge
2008-05-26 23:31:18 +01:00
committed by Thomas Gleixner
parent 955d6f1778
commit d451bb7aa8
5 changed files with 94 additions and 17 deletions
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85
arch/x86/xen/mmu.c
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@ -56,6 +56,91 @@
#include "multicalls.h"
#include "mmu.h"
/*
* This should probably be a config option. On 32-bit, it costs 1
* page/gig of memory; on 64-bit its 2 pages/gig. If we want it to be
* completely unbounded we can add another level to the p2m structure.
*/
#define MAX_GUEST_PAGES (16ull * 1024*1024*1024 / PAGE_SIZE)
#define P2M_ENTRIES_PER_PAGE (PAGE_SIZE / sizeof(unsigned long))
static unsigned long *p2m_top[MAX_GUEST_PAGES / P2M_ENTRIES_PER_PAGE];
static inline unsigned p2m_top_index(unsigned long pfn)
{
BUG_ON(pfn >= MAX_GUEST_PAGES);
return pfn / P2M_ENTRIES_PER_PAGE;
}
static inline unsigned p2m_index(unsigned long pfn)
{
return pfn % P2M_ENTRIES_PER_PAGE;
}
void __init xen_build_dynamic_phys_to_machine(void)
{
unsigned pfn;
unsigned long *mfn_list = (unsigned long *)xen_start_info->mfn_list;
BUG_ON(xen_start_info->nr_pages >= MAX_GUEST_PAGES);
for(pfn = 0;
pfn < xen_start_info->nr_pages;
pfn += P2M_ENTRIES_PER_PAGE) {
unsigned topidx = p2m_top_index(pfn);
p2m_top[topidx] = &mfn_list[pfn];
}
}
unsigned long get_phys_to_machine(unsigned long pfn)
{
unsigned topidx, idx;
topidx = p2m_top_index(pfn);
if (p2m_top[topidx] == NULL)
return INVALID_P2M_ENTRY;
idx = p2m_index(pfn);
return p2m_top[topidx][idx];
}
static void alloc_p2m(unsigned long **pp)
{
unsigned long *p;
unsigned i;
p = (void *)__get_free_page(GFP_KERNEL | __GFP_NOFAIL);
BUG_ON(p == NULL);
for(i = 0; i < P2M_ENTRIES_PER_PAGE; i++)
p[i] = INVALID_P2M_ENTRY;
if (cmpxchg(pp, NULL, p) != NULL)
free_page((unsigned long)p);
}
void set_phys_to_machine(unsigned long pfn, unsigned long mfn)
{
unsigned topidx, idx;
if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) {
BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
return;
}
topidx = p2m_top_index(pfn);
if (p2m_top[topidx] == NULL) {
/* no need to allocate a page to store an invalid entry */
if (mfn == INVALID_P2M_ENTRY)
return;
alloc_p2m(&p2m_top[topidx]);
}
idx = p2m_index(pfn);
p2m_top[topidx][idx] = mfn;
}
xmaddr_t arbitrary_virt_to_machine(unsigned long address)
{
unsigned int level;