hw/arm/virt: Add properties to disable high memory regions

The 3 high memory regions are usually enabled by default, but they may
be not used. For example, VIRT_HIGH_GIC_REDIST2 isn't needed by GICv2.
This leads to waste in the PA space.

Add properties ("highmem-redists", "highmem-ecam", "highmem-mmio") to
allow users selectively disable them if needed. After that, the high
memory region for GICv3 or GICv4 redistributor can be disabled by user,
the number of maximal supported CPUs needs to be calculated based on
'vms->highmem_redists'. The follow-up error message is also improved
to indicate if the high memory region for GICv3 and GICv4 has been
enabled or not.

Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Message-id: 20221029224307.138822-8-gshan@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 73 insertions, 2 deletions

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 3d1371c..0acb71b 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -2096,14 +2096,20 @@ static void machvirt_init(MachineState *machine)
     if (vms->gic_version == VIRT_GIC_VERSION_2) {
         virt_max_cpus = GIC_NCPU;
     } else {
-        virt_max_cpus = virt_redist_capacity(vms, VIRT_GIC_REDIST) +
-            virt_redist_capacity(vms, VIRT_HIGH_GIC_REDIST2);
+        virt_max_cpus = virt_redist_capacity(vms, VIRT_GIC_REDIST);
+        if (vms->highmem_redists) {
+            virt_max_cpus += virt_redist_capacity(vms, VIRT_HIGH_GIC_REDIST2);
+        }
     }
 
     if (max_cpus > virt_max_cpus) {
         error_report("Number of SMP CPUs requested (%d) exceeds max CPUs "
                      "supported by machine 'mach-virt' (%d)",
                      max_cpus, virt_max_cpus);
+        if (vms->gic_version != VIRT_GIC_VERSION_2 && !vms->highmem_redists) {
+            error_printf("Try 'highmem-redists=on' for more CPUs\n");
+        }
+
         exit(1);
     }
 
@@ -2372,6 +2378,49 @@ static void virt_set_compact_highmem(Object *obj, bool value, Error **errp)
     vms->highmem_compact = value;
 }
 
+static bool virt_get_highmem_redists(Object *obj, Error **errp)
+{
+    VirtMachineState *vms = VIRT_MACHINE(obj);
+
+    return vms->highmem_redists;
+}
+
+static void virt_set_highmem_redists(Object *obj, bool value, Error **errp)
+{
+    VirtMachineState *vms = VIRT_MACHINE(obj);
+
+    vms->highmem_redists = value;
+}
+
+static bool virt_get_highmem_ecam(Object *obj, Error **errp)
+{
+    VirtMachineState *vms = VIRT_MACHINE(obj);
+
+    return vms->highmem_ecam;
+}
+
+static void virt_set_highmem_ecam(Object *obj, bool value, Error **errp)
+{
+    VirtMachineState *vms = VIRT_MACHINE(obj);
+
+    vms->highmem_ecam = value;
+}
+
+static bool virt_get_highmem_mmio(Object *obj, Error **errp)
+{
+    VirtMachineState *vms = VIRT_MACHINE(obj);
+
+    return vms->highmem_mmio;
+}
+
+static void virt_set_highmem_mmio(Object *obj, bool value, Error **errp)
+{
+    VirtMachineState *vms = VIRT_MACHINE(obj);
+
+    vms->highmem_mmio = value;
+}
+
+
 static bool virt_get_its(Object *obj, Error **errp)
 {
     VirtMachineState *vms = VIRT_MACHINE(obj);
@@ -2997,6 +3046,28 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
                                           "Set on/off to enable/disable compact "
                                           "layout for high memory regions");
 
+    object_class_property_add_bool(oc, "highmem-redists",
+                                   virt_get_highmem_redists,
+                                   virt_set_highmem_redists);
+    object_class_property_set_description(oc, "highmem-redists",
+                                          "Set on/off to enable/disable high "
+                                          "memory region for GICv3 or GICv4 "
+                                          "redistributor");
+
+    object_class_property_add_bool(oc, "highmem-ecam",
+                                   virt_get_highmem_ecam,
+                                   virt_set_highmem_ecam);
+    object_class_property_set_description(oc, "highmem-ecam",
+                                          "Set on/off to enable/disable high "
+                                          "memory region for PCI ECAM");
+
+    object_class_property_add_bool(oc, "highmem-mmio",
+                                   virt_get_highmem_mmio,
+                                   virt_set_highmem_mmio);
+    object_class_property_set_description(oc, "highmem-mmio",
+                                          "Set on/off to enable/disable high "
+                                          "memory region for PCI MMIO");
+
     object_class_property_add_str(oc, "gic-version", virt_get_gic_version,
                                   virt_set_gic_version);
     object_class_property_set_description(oc, "gic-version",