From 5006ea1344d134356a9b2e1afd521cf8df0c6a85 Mon Sep 17 00:00:00 2001
From: Magnus Kulke <magnuskulke@linux.microsoft.com>
Date: Tue, 16 Sep 2025 18:48:28 +0200
Subject: [PATCH] accel/mshv: Register memory region listeners

Add memory listener hooks for the MSHV accelerator to track guest
memory regions. This enables the backend to respond to region
additions, removals and will be used to manage guest memory mappings
inside the hypervisor.

Actually registering physical memory in the hypervisor is still stubbed
out.

Signed-off-by: Magnus Kulke <magnuskulke@linux.microsoft.com>
Link: https://lore.kernel.org/r/20250916164847.77883-9-magnuskulke@linux.microsoft.com
[mshv.h/mshv_int.h split. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 accel/mshv/mem.c          | 25 +++++++++++++++
 accel/mshv/meson.build    |  1 +
 accel/mshv/mshv-all.c     | 67 +++++++++++++++++++++++++++++++++++++--
 include/system/mshv_int.h |  4 +++
 4 files changed, 95 insertions(+), 2 deletions(-)
 create mode 100644 accel/mshv/mem.c

diff --git a/accel/mshv/mem.c b/accel/mshv/mem.c
new file mode 100644
index 0000000000..9889918c31
--- /dev/null
+++ b/accel/mshv/mem.c
@@ -0,0 +1,25 @@
+/*
+ * QEMU MSHV support
+ *
+ * Copyright Microsoft, Corp. 2025
+ *
+ * Authors:
+ *  Magnus Kulke      <magnuskulke@microsoft.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/error-report.h"
+#include "system/address-spaces.h"
+#include "system/mshv.h"
+#include "system/mshv_int.h"
+
+void mshv_set_phys_mem(MshvMemoryListener *mml, MemoryRegionSection *section,
+                       bool add)
+{
+    error_report("unimplemented");
+    abort();
+}
+
diff --git a/accel/mshv/meson.build b/accel/mshv/meson.build
index 4c03ac7921..8a6beb3fb1 100644
--- a/accel/mshv/meson.build
+++ b/accel/mshv/meson.build
@@ -1,5 +1,6 @@
 mshv_ss = ss.source_set()
 mshv_ss.add(if_true: files(
+  'mem.c',
   'mshv-all.c'
 ))
 
diff --git a/accel/mshv/mshv-all.c b/accel/mshv/mshv-all.c
index ae12f0f58b..a684a36677 100644
--- a/accel/mshv/mshv-all.c
+++ b/accel/mshv/mshv-all.c
@@ -49,10 +49,73 @@ bool mshv_allowed;
 
 MshvState *mshv_state;
 
+static void mem_region_add(MemoryListener *listener,
+                           MemoryRegionSection *section)
+{
+    MshvMemoryListener *mml;
+    mml = container_of(listener, MshvMemoryListener, listener);
+    memory_region_ref(section->mr);
+    mshv_set_phys_mem(mml, section, true);
+}
+
+static void mem_region_del(MemoryListener *listener,
+                           MemoryRegionSection *section)
+{
+    MshvMemoryListener *mml;
+    mml = container_of(listener, MshvMemoryListener, listener);
+    mshv_set_phys_mem(mml, section, false);
+    memory_region_unref(section->mr);
+}
+
+static MemoryListener mshv_memory_listener = {
+    .name = "mshv",
+    .priority = MEMORY_LISTENER_PRIORITY_ACCEL,
+    .region_add = mem_region_add,
+    .region_del = mem_region_del,
+};
+
+static MemoryListener mshv_io_listener = {
+    .name = "mshv", .priority = MEMORY_LISTENER_PRIORITY_DEV_BACKEND,
+    /* MSHV does not support PIO eventfd */
+};
+
+static void register_mshv_memory_listener(MshvState *s, MshvMemoryListener *mml,
+                                          AddressSpace *as, int as_id,
+                                          const char *name)
+{
+    int i;
+
+    mml->listener = mshv_memory_listener;
+    mml->listener.name = name;
+    memory_listener_register(&mml->listener, as);
+    for (i = 0; i < s->nr_as; ++i) {
+        if (!s->as[i].as) {
+            s->as[i].as = as;
+            s->as[i].ml = mml;
+            break;
+        }
+    }
+}
+
 static int mshv_init(AccelState *as, MachineState *ms)
 {
-    error_report("unimplemented");
-    abort();
+    MshvState *s;
+    s = MSHV_STATE(as);
+
+    accel_blocker_init();
+
+    s->vm = 0;
+
+    s->nr_as = 1;
+    s->as = g_new0(MshvAddressSpace, s->nr_as);
+
+    mshv_state = s;
+
+    register_mshv_memory_listener(s, &s->memory_listener, &address_space_memory,
+                                  0, "mshv-memory");
+    memory_listener_register(&mshv_io_listener, &address_space_io);
+
+    return 0;
 }
 
 static void mshv_start_vcpu_thread(CPUState *cpu)
diff --git a/include/system/mshv_int.h b/include/system/mshv_int.h
index 132491b599..cfa177ff72 100644
--- a/include/system/mshv_int.h
+++ b/include/system/mshv_int.h
@@ -38,4 +38,8 @@ struct MshvState {
     MshvAddressSpace *as;
 };
 
+/* memory */
+void mshv_set_phys_mem(MshvMemoryListener *mml, MemoryRegionSection *section,
+                       bool add);
+
 #endif
-- 
2.47.3