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    Subject[Xen-devel] [PATCH -v2] xen: populate correct number of pages when across mem boundary
    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.

    -v2: If xen_do_chunk fail(populate), abort this chunk and any others.
    Suggested by David, thanks.

    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>
    ---
    diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
    index a4790bf..ead8557 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;
    }
    --
    1.7.3


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