xen: populate correct number of pages when across mem boundary (v2)

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: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 9 insertions, 14 deletions

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index a4790bf22c59..ead85576d54a 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -157,25 +157,24 @@ static unsigned long __init xen_populate_chunk(
         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
@@ -184,23 +183,19 @@ static unsigned long __init xen_populate_chunk(
                         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;
 }