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* [PATCH] x86/xen: Fix xen_e820_swap_entry_with_ram()
@ 2026-05-05 10:24 Juergen Gross
  2026-05-05 10:25 ` Jan Beulich
  0 siblings, 1 reply; 2+ messages in thread
From: Juergen Gross @ 2026-05-05 10:24 UTC (permalink / raw)
  To: linux-kernel, x86
  Cc: Juergen Gross, Boris Ostrovsky, Thomas Gleixner, Ingo Molnar,
	Borislav Petkov, Dave Hansen, H. Peter Anvin, xen-devel,
	Jan Beulich

When swapping a not page-aligned E820 map entry with RAM, the start
address of the modified entry is calculated wrong (the offset into the
page is subtracted instead of being added to the page address).

Fixes: be35d91c8880 ("xen: tolerate ACPI NVS memory overlapping with Xen allocated memory")
Reported-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
 arch/x86/xen/setup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index bb95a05259b8..41251d4cf953 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -655,7 +655,7 @@ static void __init xen_e820_swap_entry_with_ram(struct e820_entry *swap_entry)
 			/* Fill new entry (keep size and page offset). */
 			entry->type = swap_entry->type;
 			entry->addr = entry_end - swap_size +
-				      swap_addr - swap_entry->addr;
+				      swap_entry->addr - swap_addr;
 			entry->size = swap_entry->size;
 
 			/* Convert old entry to RAM, align to pages. */
-- 
2.54.0


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2026-05-05 10:24 [PATCH] x86/xen: Fix xen_e820_swap_entry_with_ram() Juergen Gross
2026-05-05 10:25 ` Jan Beulich

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