At the moment kvmtool always tries to instantiate a virtual GICv2
interrupt controller for the guest, and fails with some scary error
message if that doesn't work.
The user has then to manually specify "--irqchip=gicv3", which is not
really obvious.
With the advent of more GICv3-only machines, let's try to be more
clever and implement some auto-detection of the GIC type needed:
We try gicv3-its, gicv3, gicv2m and gicv2, in that order. The first one
succeeding wins.
For GICv2 machines the first two will always fail.
On GICv3 machines offering GICv2 compatibility we used to prefer a
virtual GICv2 in the guest, but these days the GICv3 support both in
guests and in KVM is equally mature and wide-spread, so we should use
the GICv3 emulation for the guest as well.
This algorithm is in effect is there is no explicit --irqchip parameter
on the command line. We still allow the GIC type to be set explicitly.
Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
---
arm/gic.c | 16 ++++++++++++++++
arm/include/arm-common/gic.h | 1 +
2 files changed, 17 insertions(+)
diff --git a/arm/gic.c b/arm/gic.c
index abcbcc09..26be4b4c 100644
--- a/arm/gic.c
+++ b/arm/gic.c
@@ -182,6 +182,8 @@ static int gic__create_device(struct kvm *kvm, enum irqchip_type type)
gic_device.type = KVM_DEV_TYPE_ARM_VGIC_V3;
dist_attr.attr = KVM_VGIC_V3_ADDR_TYPE_DIST;
break;
+ case IRQCHIP_AUTO:
+ return -ENODEV;
}
err = ioctl(kvm->vm_fd, KVM_CREATE_DEVICE, &gic_device);
@@ -199,6 +201,8 @@ static int gic__create_device(struct kvm *kvm, enum irqchip_type type)
case IRQCHIP_GICV3:
err = ioctl(gic_fd, KVM_SET_DEVICE_ATTR, &redist_attr);
break;
+ case IRQCHIP_AUTO:
+ return -ENODEV;
}
if (err)
goto out_err;
@@ -249,9 +253,21 @@ static int gic__create_irqchip(struct kvm *kvm)
int gic__create(struct kvm *kvm, enum irqchip_type type)
{
+ enum irqchip_type try;
int err;
switch (type) {
+ case IRQCHIP_AUTO:
+ for (try = IRQCHIP_GICV3_ITS; try >= IRQCHIP_GICV2; try--) {
+ err = gic__create(kvm, try);
+ if (!err)
+ break;
+ }
+ if (err)
+ return err;
+
+ kvm->cfg.arch.irqchip = try;
+ return 0;
case IRQCHIP_GICV2M:
gic_msi_size = KVM_VGIC_V2M_SIZE;
gic_msi_base = ARM_GIC_CPUI_BASE - gic_msi_size;
diff --git a/arm/include/arm-common/gic.h b/arm/include/arm-common/gic.h
index 1125d601..ec9cf31a 100644
--- a/arm/include/arm-common/gic.h
+++ b/arm/include/arm-common/gic.h
@@ -24,6 +24,7 @@
#define KVM_VGIC_V2M_SIZE 0x1000
enum irqchip_type {
+ IRQCHIP_AUTO,
IRQCHIP_GICV2,
IRQCHIP_GICV2M,
IRQCHIP_GICV3,
--
2.17.1
