hw/arm/virt: Only describe cpu topology since virt-6.2

On existing older machine types, without cpu topology described
in ACPI or DT, the guest will populate one by default. With the
topology described, it will read the information and set up its
topology as instructed, but that may not be the same as what was
getting used by default. It's possible that an user application
has a dependency on the default topology and if the default one
gets changed it will probably behave differently.

Based on above consideration we'd better only describe topology
information to the guest on 6.2 and later machine types.

Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Message-Id: <20211020142125.7516-2-wangyanan55@huawei.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 4160d49688c8970339ca63e68fb973292df18882..15e8d8cf4acc465609244d9b8976839863daad6a 100644 (file)
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -2816,6 +2816,7 @@ static void virt_machine_6_1_options(MachineClass *mc)
     virt_machine_6_2_options(mc);
     compat_props_add(mc->compat_props, hw_compat_6_1, hw_compat_6_1_len);
     mc->smp_props.prefer_sockets = true;
+    vmc->no_cpu_topology = true;
 
     /* qemu ITS was introduced with 6.2 */
     vmc->no_tcg_its = true;

diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
index b461b8d261db8eb2f19dd918e61a2b5cce27b219..dc6b66ffc8f8ceffcb1d83dc9909583e0a500828 100644 (file)
--- a/include/hw/arm/virt.h
+++ b/include/hw/arm/virt.h
@@ -125,11 +125,13 @@ struct VirtMachineClass {
     bool claim_edge_triggered_timers;
     bool smbios_old_sys_ver;
     bool no_highmem_ecam;
-    bool no_ged;   /* Machines < 4.2 has no support for ACPI GED device */
+    bool no_ged;   /* Machines < 4.2 have no support for ACPI GED device */
     bool kvm_no_adjvtime;
     bool no_kvm_steal_time;
     bool acpi_expose_flash;
     bool no_secure_gpio;
+    /* Machines < 6.2 have no support for describing cpu topology to guest */
+    bool no_cpu_topology;
 };
 
 struct VirtMachineState {