[PATCH 3.4 86/88] xen: populate correct number of pages when across mem boundary (v2)

Greg Kroah-Hartman
2014-06-10T00:25:36Z

From: "zhenzhong.duan" <zhenzhong.duan@oracle.com>

commit c3d93f880197953f86ab90d9da4744e926b38e33 upstream.

When populate pages across a mem boundary at bootup, the page count
populated isn't correct. This is due to mem populated to non-mem
region and ignored.

Pfn range is also wrongly aligned when mem boundary isn't page aligned.

For a dom0 booted with dom_mem=3368952K(0xcd9ff000-4k) dmesg diff is:
[ 0.000000] Freeing 9e-100 pfn range: 98 pages freed
[ 0.000000] 1-1 mapping on 9e->100
[ 0.000000] 1-1 mapping on cd9ff->100000
[ 0.000000] Released 98 pages of unused memory
[ 0.000000] Set 206435 page(s) to 1-1 mapping
-[ 0.000000] Populating cd9fe-cda00 pfn range: 1 pages added
+[ 0.000000] Populating cd9fe-cd9ff pfn range: 1 pages added
+[ 0.000000] Populating 100000-100061 pfn range: 97 pages added
[ 0.000000] BIOS-provided physical RAM map:
[ 0.000000] Xen: 0000000000000000 - 000000000009e000 (usable)
[ 0.000000] Xen: 00000000000a0000 - 0000000000100000 (reserved)
[ 0.000000] Xen: 0000000000100000 - 00000000cd9ff000 (usable)
[ 0.000000] Xen: 00000000cd9ffc00 - 00000000cda53c00 (ACPI NVS)
...
[ 0.000000] Xen: 0000000100000000 - 0000000100061000 (usable)
[ 0.000000] Xen: 0000000100061000 - 000000012c000000 (unusable)
...
[ 0.000000] MEMBLOCK configuration:
...
-[ 0.000000] reserved[0x4] [0x000000cd9ff000-0x000000cd9ffbff], 0xc00 bytes
-[ 0.000000] reserved[0x5] [0x00000100000000-0x00000100060fff], 0x61000 bytes

Related xen memory layout:
(XEN) Xen-e820 RAM map:
(XEN) 0000000000000000 - 000000000009ec00 (usable)
(XEN) 00000000000f0000 - 0000000000100000 (reserved)
(XEN) 0000000000100000 - 00000000cd9ffc00 (usable)

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
[v2: If xen_do_chunk fail(populate), abort this chunk and any others]
Suggested by David, thanks.
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/xen/setup.c | 23 +++++++++--------------
1 file changed, 9 insertions(+), 14 deletions(-)

--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -165,25 +165,24 @@ static unsigned long __init xen_populate
unsigned long dest_pfn;

for (i = 0, entry = list; i < map_size; i++, entry++) {
- unsigned long credits = credits_left;
unsigned long s_pfn;
unsigned long e_pfn;
unsigned long pfns;
long capacity;

- if (credits <= 0)
+ if (credits_left <= 0)
break;

if (entry->type != E820_RAM)
continue;

- e_pfn = PFN_UP(entry->addr + entry->size);
+ e_pfn = PFN_DOWN(entry->addr + entry->size);

/* We only care about E820 after the xen_start_info->nr_pages */
if (e_pfn <= max_pfn)
continue;

- s_pfn = PFN_DOWN(entry->addr);
+ s_pfn = PFN_UP(entry->addr);
/* If the E820 falls within the nr_pages, we want to start
* at the nr_pages PFN.
* If that would mean going past the E820 entry, skip it
@@ -192,23 +191,19 @@ static unsigned long __init xen_populate
capacity = e_pfn - max_pfn;
dest_pfn = max_pfn;
} else {
- /* last_pfn MUST be within E820_RAM regions */
- if (*last_pfn && e_pfn >= *last_pfn)
- s_pfn = *last_pfn;
capacity = e_pfn - s_pfn;
dest_pfn = s_pfn;
}
- /* If we had filled this E820_RAM entry, go to the next one. */
- if (capacity <= 0)
- continue;

- if (credits > capacity)
- credits = capacity;
+ if (credits_left < capacity)
+ capacity = credits_left;

- pfns = xen_do_chunk(dest_pfn, dest_pfn + credits, false);
+ pfns = xen_do_chunk(dest_pfn, dest_pfn + capacity, false);
done += pfns;
- credits_left -= pfns;
*last_pfn = (dest_pfn + pfns);
+ if (pfns < capacity)
+ break;
+ credits_left -= pfns;
}
return done;
}