linux-kernel - [PATCH v2 1/2] mm/memory_hotplug: Add support to accept memory during hot-add

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Message-ID: <20260112202300.43546-2-prsampat@amd.com>
Date: Mon, 12 Jan 2026 14:22:59 -0600
From: "Pratik R. Sampat" <prsampat@....com>
To: <linux-mm@...ck.org>, <linux-coco@...ts.linux.dev>, <x86@...nel.org>,
	<linux-kernel@...r.kernel.org>
CC: <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>, <kas@...nel.org>, <ardb@...nel.org>,
	<akpm@...ux-foundation.org>, <david@...nel.org>, <osalvador@...e.de>,
	<thomas.lendacky@....com>, <michael.roth@....com>, <prsampat@....com>
Subject: [PATCH v2 1/2] mm/memory_hotplug: Add support to accept memory during hot-add

Confidential computing guests require memory to be accepted before use.
The unaccepted memory bitmap maintained by firmware does not track
hotplugged memory ranges.

Call arch_accept_memory() during the hot-add path to explicitly validate
and transition the newly added memory to a private state, making it
usable by the guest.

Signed-off-by: Pratik R. Sampat <prsampat@....com>
---
 mm/memory_hotplug.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index a63ec679d861..8cfbf0541430 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -38,6 +38,7 @@
 #include <linux/node.h>
 
 #include <asm/tlbflush.h>
+#include <asm/unaccepted_memory.h>
 
 #include "internal.h"
 #include "shuffle.h"
@@ -1567,6 +1568,9 @@ int add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
 	if (!strcmp(res->name, "System RAM"))
 		firmware_map_add_hotplug(start, start + size, "System RAM");
 
+	if (IS_ENABLED(CONFIG_UNACCEPTED_MEMORY))
+		arch_accept_memory(start, start + size);
+
 	/* device_online() will take the lock when calling online_pages() */
 	mem_hotplug_done();
 
-- 
2.52.0