[PATCH v5 02/13] accel/mshv: add arch-specific accelerator init hook

From: "Anirudh Rayabharam (Microsoft)" <[email protected]>

Introduce mshv_arch_accel_init() as an arch-specific hook called early
in mshv_init(), before VM creation. This allows each architecture to
perform platform-specific initialization at accelerator init time.

For x86, the hook calls mshv_init_mmio_emu() which was previously called
directly from the common init path. Also move set_unimplemented_msr_action()
and mshv_arch_post_init_vm() from mshv-cpu.c to the new mshv-all.c, as
they are not vCPU-specific.

Signed-off-by: Anirudh Rayabharam (Microsoft) <[email protected]>
---
 accel/mshv/mshv-all.c        |  5 ++-
 include/system/mshv_int.h    |  1 +
 target/i386/mshv/meson.build |  1 +
 target/i386/mshv/mshv-all.c  | 80 ++++++++++++++++++++++++++++++++++++++++++++
 target/i386/mshv/mshv-cpu.c  | 40 ----------------------
 5 files changed, 86 insertions(+), 41 deletions(-)

diff --git a/accel/mshv/mshv-all.c b/accel/mshv/mshv-all.c
index 72721d0f0d..7cf99b44e0 100644
--- a/accel/mshv/mshv-all.c
+++ b/accel/mshv/mshv-all.c
@@ -557,7 +557,10 @@ static int mshv_init(AccelState *as, MachineState *ms)
         return -1;
     }
 
-    mshv_init_mmio_emu();
+    ret = mshv_arch_accel_init(as, ms, mshv_fd);
+    if (ret < 0) {
+        return -1;
+    }
 
     ret = create_vm(mshv_fd, &vm_fd);
     if (ret < 0) {
diff --git a/include/system/mshv_int.h b/include/system/mshv_int.h
index e9f4a2f9b9..81e233be5f 100644
--- a/include/system/mshv_int.h
+++ b/include/system/mshv_int.h
@@ -104,6 +104,7 @@ void mshv_arch_amend_proc_features(
     union hv_partition_synthetic_processor_features *features);
 void mshv_arch_disable_partition_proc_features(
      union hv_partition_processor_features *disabled_features);
+int mshv_arch_accel_init(AccelState *as, MachineState *ms, int mshv_fd);
 int mshv_arch_post_init_vm(int vm_fd);
 void mshv_setup_hvcall_args(AccelCPUState *state);
 
diff --git a/target/i386/mshv/meson.build b/target/i386/mshv/meson.build
index 6091c21887..ce54e134cb 100644
--- a/target/i386/mshv/meson.build
+++ b/target/i386/mshv/meson.build
@@ -1,6 +1,7 @@
 i386_mshv_ss = ss.source_set()
 
 i386_mshv_ss.add(files(
+  'mshv-all.c',
   'mshv-cpu.c',
   'msr.c',
 ))
diff --git a/target/i386/mshv/mshv-all.c b/target/i386/mshv/mshv-all.c
new file mode 100644
index 0000000000..f0b43aa86f
--- /dev/null
+++ b/target/i386/mshv/mshv-all.c
@@ -0,0 +1,80 @@
+/*
+ * QEMU MSHV support
+ *
+ * Copyright Microsoft, Corp. 2026
+ *
+ * Authors: Ziqiao Zhou   <[email protected]>
+ *          Magnus Kulke  <[email protected]>
+ *          Jinank Jain   <[email protected]>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/error-report.h"
+#include "qemu/memalign.h"
+
+#include "system/mshv.h"
+#include "system/mshv_int.h"
+#include "system/address-spaces.h"
+#include "linux/mshv.h"
+#include "hw/hyperv/hvgdk.h"
+#include "hw/hyperv/hvgdk_mini.h"
+#include "hw/hyperv/hvhdk_mini.h"
+#include "hw/i386/apic_internal.h"
+
+#include "cpu.h"
+#include "emulate/x86_decode.h"
+#include "emulate/x86_emu.h"
+#include "emulate/x86_flags.h"
+
+#include "trace-accel_mshv.h"
+#include "trace.h"
+
+#include <sys/ioctl.h>
+
+int mshv_arch_accel_init(AccelState *as, MachineState *ms, int mshv_fd)
+{
+    mshv_init_mmio_emu();
+    return 0;
+}
+
+/*
+ * Default Microsoft Hypervisor behavior for unimplemented MSR is to send a
+ * fault to the guest if it tries to access it. It is possible to override
+ * this behavior with a more suitable option i.e., ignore writes from the guest
+ * and return zero in attempt to read unimplemented.
+ */
+static int set_unimplemented_msr_action(int vm_fd)
+{
+    struct hv_input_set_partition_property in = {0};
+    struct mshv_root_hvcall args = {0};
+
+    in.property_code  = HV_PARTITION_PROPERTY_UNIMPLEMENTED_MSR_ACTION;
+    in.property_value = HV_UNIMPLEMENTED_MSR_ACTION_IGNORE_WRITE_READ_ZERO;
+
+    args.code   = HVCALL_SET_PARTITION_PROPERTY;
+    args.in_sz  = sizeof(in);
+    args.in_ptr = (uint64_t)&in;
+
+    trace_mshv_hvcall_args("unimplemented_msr_action", args.code, args.in_sz);
+
+    int ret = mshv_hvcall(vm_fd, &args);
+    if (ret < 0) {
+        error_report("Failed to set unimplemented MSR action");
+        return -1;
+    }
+    return 0;
+}
+
+int mshv_arch_post_init_vm(int vm_fd)
+{
+    int ret;
+
+    ret = set_unimplemented_msr_action(vm_fd);
+    if (ret < 0) {
+        error_report("Failed to set unimplemented MSR action");
+    }
+
+    return ret;
+}
diff --git a/target/i386/mshv/mshv-cpu.c b/target/i386/mshv/mshv-cpu.c
index a142f79801..0ae1c643a6 100644
--- a/target/i386/mshv/mshv-cpu.c
+++ b/target/i386/mshv/mshv-cpu.c
@@ -2037,46 +2037,6 @@ uint32_t mshv_get_supported_cpuid(uint32_t func, uint32_t idx, int reg)
     return ret;
 }
 
-/*
- * Default Microsoft Hypervisor behavior for unimplemented MSR is to send a
- * fault to the guest if it tries to access it. It is possible to override
- * this behavior with a more suitable option i.e., ignore writes from the guest
- * and return zero in attempt to read unimplemented.
- */
-static int set_unimplemented_msr_action(int vm_fd)
-{
-    struct hv_input_set_partition_property in = {0};
-    struct mshv_root_hvcall args = {0};
-
-    in.property_code  = HV_PARTITION_PROPERTY_UNIMPLEMENTED_MSR_ACTION;
-    in.property_value = HV_UNIMPLEMENTED_MSR_ACTION_IGNORE_WRITE_READ_ZERO;
-
-    args.code   = HVCALL_SET_PARTITION_PROPERTY;
-    args.in_sz  = sizeof(in);
-    args.in_ptr = (uint64_t)&in;
-
-    trace_mshv_hvcall_args("unimplemented_msr_action", args.code, args.in_sz);
-
-    int ret = mshv_hvcall(vm_fd, &args);
-    if (ret < 0) {
-        error_report("Failed to set unimplemented MSR action");
-        return -1;
-    }
-    return 0;
-}
-
-int mshv_arch_post_init_vm(int vm_fd)
-{
-    int ret;
-
-    ret = set_unimplemented_msr_action(vm_fd);
-    if (ret < 0) {
-        error_report("Failed to set unimplemented MSR action");
-    }
-
-    return ret;
-}
-
 static void mshv_cpu_xsave_init(void)
 {
     static bool first = true;

-- 
2.45.4