From e39831f5906f5e5536eea7d7ffb8d167dfb7e959 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= <roger.pau@citrix.com>
Date: Tue, 13 Jan 2026 15:41:33 +0100
Subject: [PATCH] xen/mm: reject XENMEM_claim_pages when using LLC coloring
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The coloring allocator ignores claims; reject the usage of the hypercall if
LLC coloring is enabled.  Note that the usage of alloc_color_heap_page() is
selected at boot time, and it's a system wide decision.  Once enabled all
domains will use alloc_color_heap_page() for allocations, which ignores any
outstanding claims.

The hypercall can be enabled if/when LLC coloring is adjusted to support
claims.

Fixes: 95debe51a936 ("xen: add cache coloring allocator for domains")
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: b068cafc737d51c76b40d3f9f821017bfa15814c
master date: 2026-01-07 15:54:33 +0100
---
 xen/common/memory.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/xen/common/memory.c b/xen/common/memory.c
index 3688e6dd50..3cb6fa9495 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -16,6 +16,7 @@
 #include <xen/iocap.h>
 #include <xen/ioreq.h>
 #include <xen/lib.h>
+#include <xen/llc-coloring.h>
 #include <xen/mem_access.h>
 #include <xen/mm.h>
 #include <xen/numa.h>
@@ -1660,6 +1661,9 @@ long do_memory_op(unsigned long cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
         break;
 
     case XENMEM_claim_pages:
+        if ( llc_coloring_enabled )
+            return -EOPNOTSUPP;
+
         if ( unlikely(start_extent) )
             return -EINVAL;