qemu-kvm/kvm-hw-arm-virt-Add-properties-to-disable-high-memory-re.patch

From 30e86a7c4fbcdc95b74bcb2a15745cb221783091 Mon Sep 17 00:00:00 2001
From: Gavin Shan <gshan@redhat.com>
Date: Wed, 21 Dec 2022 08:48:45 +0800
Subject: [PATCH 7/8] hw/arm/virt: Add properties to disable high memory
 regions

RH-Author: Gavin Shan <gshan@redhat.com>
RH-MergeRequest: 126: hw/arm/virt: Optimize high memory region address assignment
RH-Bugzilla: 2113840
RH-Acked-by: Eric Auger <eric.auger@redhat.com>
RH-Acked-by: Cornelia Huck <cohuck@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Commit: [7/8] 16f8762393b447a590b31c9e4d8d3c58c6bc9fa8

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2113840

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>
(cherry picked from commit 6a48c64eec355ab1aff694eb4522d07a8e461368)
Signed-off-by: Gavin Shan <gshan@redhat.com>
Conflicts:
	hw/arm/virt.c
	Comment out the handlers of the property 'highmem-redists',
	'highmem-ecam' and 'highmem-mmio' since they aren't exposed.
---
 docs/system/arm/virt.rst | 13 +++++++
 hw/arm/virt.c            | 75 ++++++++++++++++++++++++++++++++++++++--
 2 files changed, 86 insertions(+), 2 deletions(-)

diff --git a/docs/system/arm/virt.rst b/docs/system/arm/virt.rst
index 4454706392..188a4f211f 100644
--- a/docs/system/arm/virt.rst
+++ b/docs/system/arm/virt.rst
@@ -98,6 +98,19 @@ compact-highmem
   Set ``on``/``off`` to enable/disable the compact layout for high memory regions.
   The default is ``on`` for machine types later than ``virt-7.2``.
 
+highmem-redists
+  Set ``on``/``off`` to enable/disable the high memory region for GICv3 or
+  GICv4 redistributor. The default is ``on``. Setting this to ``off`` will
+  limit the maximum number of CPUs when GICv3 or GICv4 is used.
+
+highmem-ecam
+  Set ``on``/``off`` to enable/disable the high memory region for PCI ECAM.
+  The default is ``on`` for machine types later than ``virt-3.0``.
+
+highmem-mmio
+  Set ``on``/``off`` to enable/disable the high memory region for PCI MMIO.
+  The default is ``on``.
+
 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 6087511ae9..304fa0d6e7 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -2142,14 +2142,20 @@ 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);
     }
 
@@ -2420,6 +2426,49 @@ 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;
+}
+
 #endif /* disabled for RHEL */
 
 static bool virt_get_its(Object *obj, Error **errp)
@@ -3052,6 +3101,28 @@ 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",
-- 
2.31.1