hw/boards: Add hvf_get_physical_address_range to MachineClass

This addition will be necessary for some HVF related work to follow.
For HVF on ARM there exists a set of APIs in macOS 13 to be able to
adjust the IPA size for a given VM. This is useful as by default HVF
uses 36 bits as the IPA size, so to support guests with > 64GB of RAM
we'll need to reach for this.

To have all the info necessary to carry this out however, we need some
plumbing to be able to grab the memory map and compute the highest GPA
prior to creating the VM. This is almost exactly like what kvm_type is
used for on ARM today, and is also what this will be used for. We will
compute the highest GPA and find what IPA size we'd need to satisfy this,
and if it's valid (macOS today caps at 40b) we'll set this to be the IPA
size in coming patches. This new method is only needed (today at least)
on ARM, and obviously only for HVF/macOS, so admittedly it is much less
generic than kvm_type today, but it seemed a somewhat sane way to get
the information we need from the memmap at VM creation time.

Signed-off-by: Danny Canter <danny_canter@apple.com>
Message-id: 20240828111552.93482-2-danny_canter@apple.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
[PMM: removed explicit setting of field to NULL on x86]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/arm/virt.c

@@ -2111,7 +2111,8 @@ static void machvirt_init(MachineState *machine)
 
     /*
      * In accelerated mode, the memory map is computed earlier in kvm_type()
-     * to create a VM with the right number of IPA bits.
+     * for Linux, or hvf_get_physical_address_range() for macOS to create a
+     * VM with the right number of IPA bits.
      */
     if (!vms->memmap) {
         Object *cpuobj;
@@ -3038,6 +3039,11 @@ static int virt_kvm_type(MachineState *ms, const char *type_str)
     return fixed_ipa ? 0 : requested_pa_size;
 }
 
+static int virt_hvf_get_physical_address_range(MachineState *ms)
+{
+    return 0;
+}
+
 static void virt_machine_class_init(ObjectClass *oc, void *data)
 {
     MachineClass *mc = MACHINE_CLASS(oc);
@@ -3098,6 +3104,7 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
     mc->valid_cpu_types = valid_cpu_types;
     mc->get_default_cpu_node_id = virt_get_default_cpu_node_id;
     mc->kvm_type = virt_kvm_type;
+    mc->hvf_get_physical_address_range = virt_hvf_get_physical_address_range;
     assert(!mc->get_hotplug_handler);
     mc->get_hotplug_handler = virt_machine_get_hotplug_handler;
     hc->pre_plug = virt_machine_device_pre_plug_cb;

include/hw/boards.h

@@ -215,6 +215,10 @@ typedef struct {
  *    Return the type of KVM corresponding to the kvm-type string option or
  *    computed based on other criteria such as the host kernel capabilities.
  *    kvm-type may be NULL if it is not needed.
+ * @hvf_get_physical_address_range:
+ *    Returns the physical address range in bits to use for the HVF virtual
+ *    machine based on the current boards memory map. This may be NULL if it
+ *    is not needed.
  * @numa_mem_supported:
  *    true if '--numa node.mem' option is supported and false otherwise
  * @hotplug_allowed:
@@ -256,6 +260,7 @@ struct MachineClass {
     void (*reset)(MachineState *state, ShutdownCause reason);
     void (*wakeup)(MachineState *state);
     int (*kvm_type)(MachineState *machine, const char *arg);
+    int (*hvf_get_physical_address_range)(MachineState *machine);
 
     BlockInterfaceType block_default_type;
     int units_per_default_bus;