[xen staging-4.21] x86/pod: fix decrease_reservation() clearing of M2P entries

[patchbot@xxxxxxx]

commit 79903304784c1a1ee17c16c8371c0852d6d5a655
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Tue Jan 13 15:39:31 2026 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Jan 13 15:39:31 2026 +0100

    x86/pod: fix decrease_reservation() clearing of M2P entries
    
    Add the missing index increase in the M2P clearing loop, otherwise the loop
    keeps pointlessly setting the same MFN entry repeatedly.  This seems to be
    an oversight from the change that introduced support to process high order
    pages in one go.
    
    Fixes: 3c352011c0d3 ("x86/PoD: shorten certain operations on higher order 
ranges")
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    master commit: 8e4d495cb8f70280482edae12b48f422b5715099
    master date: 2025-12-11 09:50:10 +0100
---
 xen/arch/x86/mm/p2m-pod.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/x86/mm/p2m-pod.c b/xen/arch/x86/mm/p2m-pod.c
index 05633fe2ac..22dde913cc 100644
--- a/xen/arch/x86/mm/p2m-pod.c
+++ b/xen/arch/x86/mm/p2m-pod.c
@@ -655,7 +655,7 @@ decrease_reservation(struct domain *d, gfn_t gfn, unsigned 
int order)
             }
             p2m_tlb_flush_sync(p2m);
             for ( j = 0; j < n; ++j )
-                set_gpfn_from_mfn(mfn_x(mfn), INVALID_M2P_ENTRY);
+                set_gpfn_from_mfn(mfn_x(mfn) + j, INVALID_M2P_ENTRY);
             p2m_pod_cache_add(p2m, page, cur_order);
 
             ioreq_request_mapcache_invalidate(d);
--
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