On Fri, Feb 01, 2019 at 12:37:16PM +0000, Andre Przywara wrote:
> At the moment kvmtool always tries to instantiate a virtual GICv2 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. That first one
> succeeding wins.
> For GICv2 machines the first two will always fail. For GICv2-backwards
> compatible GICv3 machines GICv3 is probably the better choice these days.
>
> 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 | 25 +++++++++++++++++++++++++
> arm/include/arm-common/gic.h | 1 +
> 2 files changed, 26 insertions(+)
>
> diff --git a/arm/gic.c b/arm/gic.c
> index abcbcc09..a86da20e 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 +253,30 @@ 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:
> + try = IRQCHIP_GICV3_ITS;
> + err = gic__create(kvm, try);
> + if (err) {
> + try = IRQCHIP_GICV3;
> + err = gic__create(kvm, try);
> + }
> + if (err) {
> + try = IRQCHIP_GICV2M;
> + err = gic__create(kvm, try);
> + }
> + if (err) {
> + try = IRQCHIP_GICV2;
> + err = gic__create(kvm, try);
> + }
> + if (err)
> + return err;
Easier to write this as a descending loop over the irqchip_type enum?
Will
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