[RFC PATCH-for-8.0 09/10] hw/virtio: Extract vhost_user_ram_slots_max() to vhost-user-target.c

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

The current definition of VHOST_USER_MAX_RAM_SLOTS is
target specific. By converting this definition to a runtime
vhost_user_ram_slots_max() helper declared in a target
specific unit, we can have the rest of vhost-user.c target
independent.

To avoid variable length array or using the heap to store
arrays of vhost_user_ram_slots_max() elements, we simply
declare an array of the biggest VHOST_USER_MAX_RAM_SLOTS,
and each target uses up to vhost_user_ram_slots_max()
elements of it. Ensure arrays are big enough by adding an
assertion in vhost_user_init().

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
RFC: Should I add VHOST_USER_MAX_RAM_SLOTS to vhost-user.h
     or create an internal header for it?
---
 hw/virtio/meson.build          |  1 +
 hw/virtio/vhost-user-target.c  | 29 +++++++++++++++++++++++++++++
 hw/virtio/vhost-user.c         | 26 +++++---------------------
 include/hw/virtio/vhost-user.h |  7 +++++++
 4 files changed, 42 insertions(+), 21 deletions(-)
 create mode 100644 hw/virtio/vhost-user-target.c

diff --git a/hw/virtio/meson.build b/hw/virtio/meson.build
index eb7ee8ea92..bf7e35fa8a 100644
--- a/hw/virtio/meson.build
+++ b/hw/virtio/meson.build
@@ -11,6 +11,7 @@ if have_vhost
   specific_virtio_ss.add(files('vhost.c', 'vhost-backend.c', 'vhost-iova-tree.c'))
   if have_vhost_user
     specific_virtio_ss.add(files('vhost-user.c'))
+    specific_virtio_ss.add(files('vhost-user-target.c'))
   endif
   if have_vhost_vdpa
     specific_virtio_ss.add(files('vhost-vdpa.c', 'vhost-shadow-virtqueue.c'))
diff --git a/hw/virtio/vhost-user-target.c b/hw/virtio/vhost-user-target.c
new file mode 100644
index 0000000000..6a0d0f53d0
--- /dev/null
+++ b/hw/virtio/vhost-user-target.c
@@ -0,0 +1,29 @@
+/*
+ * vhost-user target-specific helpers
+ *
+ * Copyright (c) 2013 Virtual Open Systems Sarl.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "hw/virtio/vhost-user.h"
+
+#if defined(TARGET_X86) || defined(TARGET_X86_64) || \
+    defined(TARGET_ARM) || defined(TARGET_ARM_64)
+#include "hw/acpi/acpi.h"
+#elif defined(TARGET_PPC) || defined(TARGET_PPC64)
+#include "hw/ppc/spapr.h"
+#endif
+
+unsigned int vhost_user_ram_slots_max(void)
+{
+#if defined(TARGET_X86) || defined(TARGET_X86_64) || \
+    defined(TARGET_ARM) || defined(TARGET_ARM_64)
+    return ACPI_MAX_RAM_SLOTS;
+#elif defined(TARGET_PPC) || defined(TARGET_PPC64)
+    return SPAPR_MAX_RAM_SLOTS;
+#else
+    return 512;
+#endif
+}
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 8f635844af..21fc176725 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -41,24 +41,7 @@
 #define VHOST_MEMORY_BASELINE_NREGIONS    8
 #define VHOST_USER_F_PROTOCOL_FEATURES 30
 #define VHOST_USER_SLAVE_MAX_FDS     8
-
-/*
- * Set maximum number of RAM slots supported to
- * the maximum number supported by the target
- * hardware plaform.
- */
-#if defined(TARGET_X86) || defined(TARGET_X86_64) || \
-    defined(TARGET_ARM) || defined(TARGET_ARM_64)
-#include "hw/acpi/acpi.h"
-#define VHOST_USER_MAX_RAM_SLOTS ACPI_MAX_RAM_SLOTS
-
-#elif defined(TARGET_PPC) || defined(TARGET_PPC64)
-#include "hw/ppc/spapr.h"
-#define VHOST_USER_MAX_RAM_SLOTS SPAPR_MAX_RAM_SLOTS
-
-#else
 #define VHOST_USER_MAX_RAM_SLOTS 512
-#endif
 
 /*
  * Maximum size of virtio device config space
@@ -935,7 +918,7 @@ static int vhost_user_add_remove_regions(struct vhost_dev *dev,
 
     if (track_ramblocks) {
         memcpy(u->postcopy_client_bases, shadow_pcb,
-               sizeof(uint64_t) * VHOST_USER_MAX_RAM_SLOTS);
+               sizeof(uint64_t) * vhost_user_ram_slots_max());
         /*
          * Now we've registered this with the postcopy code, we ack to the
          * client, because now we're in the position to be able to deal with
@@ -956,7 +939,7 @@ static int vhost_user_add_remove_regions(struct vhost_dev *dev,
 err:
     if (track_ramblocks) {
         memcpy(u->postcopy_client_bases, shadow_pcb,
-               sizeof(uint64_t) * VHOST_USER_MAX_RAM_SLOTS);
+               sizeof(uint64_t) * vhost_user_ram_slots_max());
     }
 
     return ret;
@@ -1030,7 +1013,7 @@ static int vhost_user_set_mem_table_postcopy(struct vhost_dev *dev,
         }
 
         memset(u->postcopy_client_bases, 0,
-               sizeof(uint64_t) * VHOST_USER_MAX_RAM_SLOTS);
+               sizeof(uint64_t) * vhost_user_ram_slots_max());
 
         /*
          * They're in the same order as the regions that were sent
@@ -2169,7 +2152,7 @@ static int vhost_user_backend_init(struct vhost_dev *dev, void *opaque,
                 return -EINVAL;
             }
 
-            u->user->memory_slots = MIN(ram_slots, VHOST_USER_MAX_RAM_SLOTS);
+            u->user->memory_slots = MIN(ram_slots, vhost_user_ram_slots_max());
         }
     }
 
@@ -2649,6 +2632,7 @@ static void vhost_user_state_destroy(gpointer data)
 
 bool vhost_user_init(VhostUserState *user, CharBackend *chr, Error **errp)
 {
+    assert(vhost_user_ram_slots_max() <= VHOST_USER_MAX_RAM_SLOTS);
     if (user->chr) {
         error_setg(errp, "Cannot initialize vhost-user state");
         return false;
diff --git a/include/hw/virtio/vhost-user.h b/include/hw/virtio/vhost-user.h
index 191216a74f..e13584ade8 100644
--- a/include/hw/virtio/vhost-user.h
+++ b/include/hw/virtio/vhost-user.h
@@ -86,4 +86,11 @@ void vhost_user_async_close(DeviceState *d,
                             CharBackend *chardev, struct vhost_dev *vhost,
                             vu_async_close_fn cb);
 
+/**
+ * vhost_user_ram_slots_max()
+ *
+ * Return: maximum number of RAM slots supported by the target hardware plaform.
+ */
+unsigned int vhost_user_ram_slots_max(void);
+
 #endif
-- 
2.38.1