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Re: [MINI-OS PATCH] e820: fix e820_get_reserved_pfns() to reserve page aligned area

From: Jürgen Groß <jgross@xxxxxxxx>

Date: Mon, 14 Jul 2025 16:08:20 +0200

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Cc: samuel.thibault@xxxxxxxxxxxx, minios-devel@xxxxxxxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx

Delivery-date: Mon, 14 Jul 2025 14:08:31 +0000

List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 14.07.25 16:02, Jan Beulich wrote:

On 11.07.2025 14:03, Juergen Gross wrote:

e820_get_reserved_pfns() needs to make sure to reserve only page
aligned memory areas.

Fixes: a7d27a7332ba ("mini-os: add memory map service functions")
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>


I've committed this, but ...

--- a/e820.c
+++ b/e820.c
@@ -365,7 +365,7 @@ unsigned long e820_get_reserved_pfns(int pages)
      unsigned long last = 0, needed = (long)pages << PAGE_SHIFT;

for ( i = 0; i < e820_entries && e820_map[i].addr < last + needed; i++ )

-        last = e820_map[i].addr + e820_map[i].size;
+        last = round_pgup(e820_map[i].addr + e820_map[i].size);

if ( i == 0 || e820_map[i - 1].type != E820_TYPE_SOFT_RESERVED )

          e820_insert_entry_at(i, last, needed, E820_TYPE_SOFT_RESERVED);


... I had to resolve fuzz here: There's no E820_TYPE_SOFT_RESERVED in the
upstream tree, afaics. I just hope I didn't screw up ...

Oh, I had this on top of my kexec() series. Your adaption is looking fine. Juergen

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