[PATCH v3 5/5] hw/arm/virt: Add 'highmem-compact' property

[Gavin Shan]

After the improvement to high memory region address assignment is
applied, the memory layout is changed. For example, VIRT_HIGH_PCIE_MMIO
memory region is enabled when the improvement is applied, but it's
disabled if the improvement isn't applied.

    pa_bits              = 40;
    vms->highmem_redists = false;
    vms->highmem_ecam    = false;
    vms->highmem_mmio    = true;

    # qemu-system-aarch64 -accel kvm -cpu host \
      -machine virt-7.2 -m 4G,maxmem=511G      \
      -monitor stdio

In order to keep backwords compatibility, we need to disable the
optimization on machines, which is virt-7.1 or ealier than it. It
means the optimization is enabled by default from virt-7.2. Besides,
'highmem-compact' property is added so that the optimization can be
explicitly enabled or disabled on all machine types by users.

Signed-off-by: Gavin Shan <gshan@redhat.com>
---
 docs/system/arm/virt.rst |  4 ++++
 hw/arm/virt.c            | 33 +++++++++++++++++++++++++++++++++
 include/hw/arm/virt.h    |  2 ++
 3 files changed, 39 insertions(+)

diff --git a/docs/system/arm/virt.rst b/docs/system/arm/virt.rst
index 20442ea2c1..f05ec2253b 100644
--- a/docs/system/arm/virt.rst
+++ b/docs/system/arm/virt.rst
@@ -94,6 +94,10 @@ highmem
   address space above 32 bits. The default is ``on`` for machine types
   later than ``virt-2.12``.
 
+highmem-compact
+  Set ``on``/``off`` to enable/disable compact space for high memory regions.
+  The default is ``on`` for machine types later than ``virt-7.2``
+
 gic-version
   Specify the version of the Generic Interrupt Controller (GIC) to provide.
   Valid values are:
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index b702f8f2b5..a4fbdaef91 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1734,6 +1734,13 @@ static void virt_set_high_memmap(VirtMachineState *vms,
             base = region_base + region_size;
         } else {
             *region_enabled = false;
+
+            if (!vms->highmem_compact) {
+                base = region_base + region_size;
+                if (fits) {
+                    vms->highest_gpa = region_base + region_size - 1;
+                }
+            }
         }
     }
 }
@@ -2348,6 +2355,20 @@ static void virt_set_highmem(Object *obj, bool value, 
Error **errp)
     vms->highmem = value;
 }
 
+static bool virt_get_highmem_compact(Object *obj, Error **errp)
+{
+    VirtMachineState *vms = VIRT_MACHINE(obj);
+
+    return vms->highmem_compact;
+}
+
+static void virt_set_highmem_compact(Object *obj, bool value, Error **errp)
+{
+    VirtMachineState *vms = VIRT_MACHINE(obj);
+
+    vms->highmem_compact = value;
+}
+
 static bool virt_get_its(Object *obj, Error **errp)
 {
     VirtMachineState *vms = VIRT_MACHINE(obj);
@@ -2966,6 +2987,13 @@ static void virt_machine_class_init(ObjectClass *oc, 
void *data)
                                           "Set on/off to enable/disable using "
                                           "physical address space above 32 
bits");
 
+    object_class_property_add_bool(oc, "highmem-compact",
+                                   virt_get_highmem_compact,
+                                   virt_set_highmem_compact);
+    object_class_property_set_description(oc, "highmem-compact",
+                                          "Set on/off to enable/disable 
compact "
+                                          "space for high memory regions");
+
     object_class_property_add_str(oc, "gic-version", virt_get_gic_version,
                                   virt_set_gic_version);
     object_class_property_set_description(oc, "gic-version",
@@ -3050,6 +3078,7 @@ static void virt_instance_init(Object *obj)
 
     /* High memory is enabled by default */
     vms->highmem = true;
+    vms->highmem_compact = !vmc->no_highmem_compact;
     vms->gic_version = VIRT_GIC_VERSION_NOSEL;
 
     vms->highmem_ecam = !vmc->no_highmem_ecam;
@@ -3119,8 +3148,12 @@ DEFINE_VIRT_MACHINE_AS_LATEST(7, 2)
 
 static void virt_machine_7_1_options(MachineClass *mc)
 {
+    VirtMachineClass *vmc = VIRT_MACHINE_CLASS(OBJECT_CLASS(mc));
+
     virt_machine_7_2_options(mc);
     compat_props_add(mc->compat_props, hw_compat_7_1, hw_compat_7_1_len);
+    /* Compact space for high memory regions was introduced with 7.2 */
+    vmc->no_highmem_compact = true;
 }
 DEFINE_VIRT_MACHINE(7, 1)
 
diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
index 6ec479ca2b..c7dd59d7f1 100644
--- a/include/hw/arm/virt.h
+++ b/include/hw/arm/virt.h
@@ -125,6 +125,7 @@ struct VirtMachineClass {
     bool no_pmu;
     bool claim_edge_triggered_timers;
     bool smbios_old_sys_ver;
+    bool no_highmem_compact;
     bool no_highmem_ecam;
     bool no_ged;   /* Machines < 4.2 have no support for ACPI GED device */
     bool kvm_no_adjvtime;
@@ -144,6 +145,7 @@ struct VirtMachineState {
     PFlashCFI01 *flash[2];
     bool secure;
     bool highmem;
+    bool highmem_compact;
     bool highmem_ecam;
     bool highmem_mmio;
     bool highmem_redists;
-- 
2.23.0