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authorAlex Williamson <alex.williamson@redhat.com>2019-05-14 14:14:41 -0600
committerPaolo Bonzini <pbonzini@redhat.com>2019-06-03 14:03:03 +0200
commitc87759ce876a7a0b17c2bf4f0b964bd51f0ee871 (patch)
tree1136df9621eb962326714fa330eaad310fb8de12 /hw/i386/pc_q35.c
parent7f27154d5042bae6fd9ac200e23a28ecca3387a0 (diff)
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q35: Revert to kernel irqchip
Commit b2fc91db8447 ("q35: set split kernel irqchip as default") changed the default for the pc-q35-4.0 machine type to use split irqchip, which turned out to have disasterous effects on vfio-pci INTx support. KVM resampling irqfds are registered for handling these interrupts, but these are non-functional in split irqchip mode. We can't simply test for split irqchip in QEMU as userspace handling of this interrupt is a significant performance regression versus KVM handling (GeForce GPUs assigned to Windows VMs are non-functional without forcing MSI mode or re-enabling kernel irqchip). The resolution is to revert the change in default irqchip mode in the pc-q35-4.1 machine and create a pc-q35-4.0.1 machine for the 4.0-stable branch. The qemu-q35-4.0 machine type should not be used in vfio-pci configurations for devices requiring legacy INTx support without explicitly modifying the VM configuration to use kernel irqchip. Link: https://bugs.launchpad.net/qemu/+bug/1826422 Fixes: b2fc91db8447 ("q35: set split kernel irqchip as default") Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Reviewed-by: Peter Xu <peterx@redhat.com> Message-Id: <155786484688.13873.6037015630912983760.stgit@gimli.home> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'hw/i386/pc_q35.c')
-rw-r--r--hw/i386/pc_q35.c16
1 files changed, 14 insertions, 2 deletions
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 37dd350..dcddc64 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -357,7 +357,7 @@ 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->default_kernel_irqchip_split = false;
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);
@@ -374,10 +374,22 @@ static void pc_q35_4_1_machine_options(MachineClass *m)
DEFINE_Q35_MACHINE(v4_1, "pc-q35-4.1", NULL,
pc_q35_4_1_machine_options);
-static void pc_q35_4_0_machine_options(MachineClass *m)
+static void pc_q35_4_0_1_machine_options(MachineClass *m)
{
pc_q35_4_1_machine_options(m);
m->alias = NULL;
+ compat_props_add(m->compat_props, hw_compat_4_0_1, hw_compat_4_0_1_len);
+ compat_props_add(m->compat_props, pc_compat_4_0_1, pc_compat_4_0_1_len);
+}
+
+DEFINE_Q35_MACHINE(v4_0_1, "pc-q35-4.0.1", NULL,
+ pc_q35_4_0_1_machine_options);
+
+static void pc_q35_4_0_machine_options(MachineClass *m)
+{
+ pc_q35_4_0_1_machine_options(m);
+ m->default_kernel_irqchip_split = true;
+ m->alias = NULL;
compat_props_add(m->compat_props, hw_compat_4_0, hw_compat_4_0_len);
compat_props_add(m->compat_props, pc_compat_4_0, pc_compat_4_0_len);
}