On Sun, Mar 01, 2020 at 11:40:40AM +0100, Eric Auger wrote:
> At the moment if the end-user does not specify the gic-version along
> with KVM acceleration, v2 is set by default. However most of the
> systems now have GICv3 and sometimes they do not support GICv2
> compatibility.
>
> This patch keeps the default v2 selection in all cases except
> in the KVM accelerated mode when either
> - the host does not support GICv2 in-kernel emulation or
> - number of VCPUS exceeds 8.
>
> Those cases did not work anyway so we do not break any compatibility.
> Now we get v3 selected in such a case.
>
> Signed-off-by: Eric Auger <eric.au...@redhat.com>
> Reported-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
> ---
> hw/arm/virt.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index 610bfc9ee9..2d12a7b0b8 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -1542,6 +1542,8 @@ static void virt_set_memmap(VirtMachineState *vms)
> */
> static void finalize_gic_version(VirtMachineState *vms)
> {
> + unsigned int max_cpus = MACHINE(vms)->smp.max_cpus;
> +
> if (kvm_enabled()) {
> int probe_bitmap = kvm_arm_vgic_probe();
>
> @@ -1552,7 +1554,17 @@ static void finalize_gic_version(VirtMachineState *vms)
>
> switch (vms->gic_version) {
> case VIRT_GIC_VERSION_NOSEL:
> - vms->gic_version = VIRT_GIC_VERSION_2;
> + if ((probe_bitmap & KVM_ARM_VGIC_V2 && max_cpus <= GIC_NCPU) ||
> + !kvm_irqchip_in_kernel()) {
nit: () around the bitmap & would be nice
> + vms->gic_version = VIRT_GIC_VERSION_2;
> + } else {
> + /*
> + * in case the host does not support v2 in-kernel emulation
> or
> + * the end-user requested more than 8 VCPUs we now default
> + * to v3. In any case defaulting to v2 would be broken.
> + */
> + vms->gic_version = VIRT_GIC_VERSION_3;
> + }
> break;
> case VIRT_GIC_VERSION_HOST:
> case VIRT_GIC_VERSION_MAX:
> --
> 2.20.1
>
>
