q35: set split kernel irqchip as default

Starting from QEMU 4.0, let's specify "split" as the default value for
kernel-irqchip.

So for QEMU>=4.0 we'll have: allowed=Y,required=N,split=Y
   for QEMU<=3.1 we'll have: allowed=Y,required=N,split=N
   (omitting all the "kernel_irqchip_" prefix)

Note that this will let the default q35 machine type to depend on
Linux version 4.4 or newer because that's where split irqchip is
introduced in kernel.  But it's fine since we're boosting supported
Linux version for QEMU 4.0 to around Linux 4.5.  For more information
please refer to the discussion on AMD's RDTSCP:

  https://lore.kernel.org/lkml/20181210181328.GA762@zn.tnic/

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/core/machine.c b/hw/core/machine.c
index c51423b64774847c578484a7a615e97be03ef901..4439ea663ffa171c95aa00471111a3859d77f1e6 100644 (file)
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -653,8 +653,10 @@ static void machine_class_base_init(ObjectClass *oc, void *data)
 static void machine_initfn(Object *obj)
 {
     MachineState *ms = MACHINE(obj);
+    MachineClass *mc = MACHINE_GET_CLASS(obj);
 
     ms->kernel_irqchip_allowed = true;
+    ms->kernel_irqchip_split = mc->default_kernel_irqchip_split;
     ms->kvm_shadow_mem = -1;
     ms->dump_guest_core = true;
     ms->mem_merge = true;

diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 8836d2148588e25ab4d2d1990b22093dec869deb..0a3f3f18e4f2e68d13a40ad5959d356fc3e75ae6 100644 (file)
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -304,6 +304,7 @@ static void pc_q35_machine_options(MachineClass *m)
     m->units_per_default_bus = 1;
     m->default_machine_opts = "firmware=bios-256k.bin";
     m->default_display = "std";
+    m->default_kernel_irqchip_split = true;
     m->no_floppy = 1;
     machine_class_allow_dynamic_sysbus_dev(m, TYPE_AMD_IOMMU_DEVICE);
     machine_class_allow_dynamic_sysbus_dev(m, TYPE_INTEL_IOMMU_DEVICE);
@@ -323,6 +324,7 @@ DEFINE_Q35_MACHINE(v4_0, "pc-q35-4.0", NULL,
 static void pc_q35_3_1_machine_options(MachineClass *m)
 {
     pc_q35_4_0_machine_options(m);
+    m->default_kernel_irqchip_split = false;
     m->alias = NULL;
     SET_MACHINE_COMPAT(m, PC_COMPAT_3_1);
 }

diff --git a/include/hw/boards.h b/include/hw/boards.h
index f82f28468b045a81dbdd5188d7e5ff31d8155c19..362384815e8b85ee072aa11b11932feee0b67008 100644 (file)
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -195,6 +195,7 @@ struct MachineClass {
     const char *hw_version;
     ram_addr_t default_ram_size;
     const char *default_cpu_type;
+    bool default_kernel_irqchip_split;
     bool option_rom_has_mr;
     bool rom_file_has_mr;
     int minimum_page_bits;