Re: [Qemu-arm] [RFC v2 7/7] hw/arm/virt: Register two redistributor regions when necessary

[Peter Maydell]

On 13 May 2018 at 15:35, Eric Auger <address@hidden> wrote:
> With a VGICv3 KVM device, if the number of vcpus exceeds the
> capacity of the legacy redistributor region (123 redistributors),
> we now attempt to register the second redistributor region. This
> extends the number of vcpus to 512 assuming the host kernel supports:
> - up to 512 vcpus
> - VGICv3 KVM device group/attribute:
>   KVM_DEV_ARM_VGIC_GRP_ADDR/KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION
>
> In case the host kernel does not support the registration of several
> redistributor regions, the GICv3 device initialization fails
> with a proper error message and qemu exits.
>
> Signed-off-by: Eric Auger <address@hidden>
> ---
>  hw/arm/virt.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index f35962a..8d43c51 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -531,6 +531,7 @@ static void create_gic(VirtMachineState *vms, qemu_irq 
> *pic)
>      SysBusDevice *gicbusdev;
>      const char *gictype;
>      int type = vms->gic_version, i;
> +    uint32_t nb_redist_regions = 0;
>
>      gictype = (type == 3) ? gicv3_class_name() : gic_class_name();
>
> @@ -546,15 +547,26 @@ static void create_gic(VirtMachineState *vms, qemu_irq 
> *pic)
>      }
>
>      if (type == 3) {
> -        qdev_prop_set_uint32(gicdev, "len-redist-region-count", 1);
> +        nb_redist_regions = virt_gicv3_redist_region_count(vms);
> +
> +        qdev_prop_set_uint32(gicdev, "len-redist-region-count",
> +                             nb_redist_regions);
>          qdev_prop_set_uint32(gicdev , "redist-region-count[0]",
>                               vms->memmap[VIRT_GIC_REDIST].size / 0x20000);
> +
> +        if (nb_redist_regions == 2) {
> +            qdev_prop_set_uint32(gicdev , "redist-region-count[1]",

Stray extra space before comma.

> +                                 vms->memmap[VIRT_GIC_REDIST2].size / 
> 0x20000);

This is going to ask for more redistributors than we want (cf
earlier review comment).

> +        }
>      }
>      qdev_init_nofail(gicdev);
>      gicbusdev = SYS_BUS_DEVICE(gicdev);
>      sysbus_mmio_map(gicbusdev, 0, vms->memmap[VIRT_GIC_DIST].base);
>      if (type == 3) {
>          sysbus_mmio_map(gicbusdev, 1, vms->memmap[VIRT_GIC_REDIST].base);
> +        if (nb_redist_regions == 2) {
> +            sysbus_mmio_map(gicbusdev, 2, 
> vms->memmap[VIRT_GIC_REDIST2].base);
> +        }
>      } else {
>          sysbus_mmio_map(gicbusdev, 1, vms->memmap[VIRT_GIC_CPU].base);
>      }
> @@ -1346,6 +1358,7 @@ static void machvirt_init(MachineState *machine)
>       */
>      if (vms->gic_version == 3) {
>          virt_max_cpus = vms->memmap[VIRT_GIC_REDIST].size / 0x20000;
> +        virt_max_cpus += vms->memmap[VIRT_GIC_REDIST2].size / 0x20000;

Slight pity that we can't determine whether we can support multiple
redistributor regions here, but I guess it's not a big deal.

>      } else {
>          virt_max_cpus = GIC_NCPU;
>      }
> --
> 2.5.5

thanks
-- PMM