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xen: switch extra memory accounting to use pfns
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Instead of using physical addresses for accounting of extra memory
areas available for ballooning switch to pfns as this is much less
error prone regarding partial pages.

Reported-by: Roger Pau Monné <roger.pau@citrix.com>
Tested-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
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Juergen Gross authored and David Vrabel committed Sep 8, 2015
1 parent cb9e444 commit 626d750
Showing 3 changed files with 49 additions and 41 deletions.
80 changes: 44 additions & 36 deletions arch/x86/xen/setup.c
View file
Original file line number Diff line number Diff line change
@@ -90,62 +90,69 @@ static void __init xen_parse_512gb(void)
xen_512gb_limit = val;
}

static void __init xen_add_extra_mem(phys_addr_t start, phys_addr_t size)
static void __init xen_add_extra_mem(unsigned long start_pfn,
unsigned long n_pfns)
{
int i;

/*
* No need to check for zero size, should happen rarely and will only
* write a new entry regarded to be unused due to zero size.
*/
for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
/* Add new region. */
if (xen_extra_mem[i].size == 0) {
xen_extra_mem[i].start = start;
xen_extra_mem[i].size = size;
if (xen_extra_mem[i].n_pfns == 0) {
xen_extra_mem[i].start_pfn = start_pfn;
xen_extra_mem[i].n_pfns = n_pfns;
break;
}
/* Append to existing region. */
if (xen_extra_mem[i].start + xen_extra_mem[i].size == start) {
xen_extra_mem[i].size += size;
if (xen_extra_mem[i].start_pfn + xen_extra_mem[i].n_pfns ==
start_pfn) {
xen_extra_mem[i].n_pfns += n_pfns;
break;
}
}
if (i == XEN_EXTRA_MEM_MAX_REGIONS)
printk(KERN_WARNING "Warning: not enough extra memory regions\n");

memblock_reserve(start, size);
memblock_reserve(PFN_PHYS(start_pfn), PFN_PHYS(n_pfns));
}

static void __init xen_del_extra_mem(phys_addr_t start, phys_addr_t size)
static void __init xen_del_extra_mem(unsigned long start_pfn,
unsigned long n_pfns)
{
int i;
phys_addr_t start_r, size_r;
unsigned long start_r, size_r;

for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
start_r = xen_extra_mem[i].start;
size_r = xen_extra_mem[i].size;
start_r = xen_extra_mem[i].start_pfn;
size_r = xen_extra_mem[i].n_pfns;

/* Start of region. */
if (start_r == start) {
BUG_ON(size > size_r);
xen_extra_mem[i].start += size;
xen_extra_mem[i].size -= size;
if (start_r == start_pfn) {
BUG_ON(n_pfns > size_r);
xen_extra_mem[i].start_pfn += n_pfns;
xen_extra_mem[i].n_pfns -= n_pfns;
break;
}
/* End of region. */
if (start_r + size_r == start + size) {
BUG_ON(size > size_r);
xen_extra_mem[i].size -= size;
if (start_r + size_r == start_pfn + n_pfns) {
BUG_ON(n_pfns > size_r);
xen_extra_mem[i].n_pfns -= n_pfns;
break;
}
/* Mid of region. */
if (start > start_r && start < start_r + size_r) {
BUG_ON(start + size > start_r + size_r);
xen_extra_mem[i].size = start - start_r;
if (start_pfn > start_r && start_pfn < start_r + size_r) {
BUG_ON(start_pfn + n_pfns > start_r + size_r);
xen_extra_mem[i].n_pfns = start_pfn - start_r;
/* Calling memblock_reserve() again is okay. */
xen_add_extra_mem(start + size, start_r + size_r -
(start + size));
xen_add_extra_mem(start_pfn + n_pfns, start_r + size_r -
(start_pfn + n_pfns));
break;
}
}
memblock_free(start, size);
memblock_free(PFN_PHYS(start_pfn), PFN_PHYS(n_pfns));
}

/*
@@ -156,11 +163,10 @@ static void __init xen_del_extra_mem(phys_addr_t start, phys_addr_t size)
unsigned long __ref xen_chk_extra_mem(unsigned long pfn)
{
int i;
phys_addr_t addr = PFN_PHYS(pfn);

for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
if (addr >= xen_extra_mem[i].start &&
addr < xen_extra_mem[i].start + xen_extra_mem[i].size)
if (pfn >= xen_extra_mem[i].start_pfn &&
pfn < xen_extra_mem[i].start_pfn + xen_extra_mem[i].n_pfns)
return INVALID_P2M_ENTRY;
}

@@ -176,10 +182,10 @@ void __init xen_inv_extra_mem(void)
int i;

for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
if (!xen_extra_mem[i].size)
if (!xen_extra_mem[i].n_pfns)
continue;
pfn_s = PFN_DOWN(xen_extra_mem[i].start);
pfn_e = PFN_UP(xen_extra_mem[i].start + xen_extra_mem[i].size);
pfn_s = xen_extra_mem[i].start_pfn;
pfn_e = pfn_s + xen_extra_mem[i].n_pfns;
for (pfn = pfn_s; pfn < pfn_e; pfn++)
set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
}
@@ -507,7 +513,7 @@ void __init xen_remap_memory(void)
} else if (pfn_s + len == xen_remap_buf.target_pfn) {
len += xen_remap_buf.size;
} else {
xen_del_extra_mem(PFN_PHYS(pfn_s), PFN_PHYS(len));
xen_del_extra_mem(pfn_s, len);
pfn_s = xen_remap_buf.target_pfn;
len = xen_remap_buf.size;
}
@@ -517,7 +523,7 @@ void __init xen_remap_memory(void)
}

if (pfn_s != ~0UL && len)
xen_del_extra_mem(PFN_PHYS(pfn_s), PFN_PHYS(len));
xen_del_extra_mem(pfn_s, len);

set_pte_mfn(buf, mfn_save, PAGE_KERNEL);

@@ -744,7 +750,7 @@ static void __init xen_reserve_xen_mfnlist(void)
**/
char * __init xen_memory_setup(void)
{
unsigned long max_pfn;
unsigned long max_pfn, pfn_s, n_pfns;
phys_addr_t mem_end, addr, size, chunk_size;
u32 type;
int rc;
@@ -831,9 +837,11 @@ char * __init xen_memory_setup(void)
chunk_size = min(size, mem_end - addr);
} else if (extra_pages) {
chunk_size = min(size, PFN_PHYS(extra_pages));
extra_pages -= PFN_DOWN(chunk_size);
xen_add_extra_mem(addr, chunk_size);
xen_max_p2m_pfn = PFN_DOWN(addr + chunk_size);
pfn_s = PFN_UP(addr);
n_pfns = PFN_DOWN(addr + chunk_size) - pfn_s;
extra_pages -= n_pfns;
xen_add_extra_mem(pfn_s, n_pfns);
xen_max_p2m_pfn = pfn_s + n_pfns;
} else
type = E820_UNUSABLE;
}
6 changes: 3 additions & 3 deletions drivers/xen/balloon.c
View file
Original file line number Diff line number Diff line change
@@ -638,9 +638,9 @@ static int __init balloon_init(void)
* regions (see arch/x86/xen/setup.c).
*/
for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++)
if (xen_extra_mem[i].size)
balloon_add_region(PFN_UP(xen_extra_mem[i].start),
PFN_DOWN(xen_extra_mem[i].size));
if (xen_extra_mem[i].n_pfns)
balloon_add_region(xen_extra_mem[i].start_pfn,
xen_extra_mem[i].n_pfns);

return 0;
}
4 changes: 2 additions & 2 deletions include/xen/page.h
View file
Original file line number Diff line number Diff line change
@@ -9,8 +9,8 @@ static inline unsigned long page_to_mfn(struct page *page)
}

struct xen_memory_region {
phys_addr_t start;
phys_addr_t size;
unsigned long start_pfn;
unsigned long n_pfns;
};

#define XEN_EXTRA_MEM_MAX_REGIONS 128 /* == E820MAX */

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