Re: [PATCH v2 8/8] hw/arm/virt: add ITS support in virt GIC

[Peter Maydell]

On Thu, 1 Apr 2021 at 03:42, Shashi Mallela <shashi.mallela@linaro.org> wrote:
>
> Included creation of ITS as part of virt platform GIC
> initialization.This Emulated ITS model now co-exists with kvm
> ITS and is enabled in absence of kvm irq kernel support in a
> platform.
>
> Signed-off-by: Shashi Mallela <shashi.mallela@linaro.org>
> ---
>  hw/arm/virt.c        | 10 ++++++++--
>  target/arm/kvm_arm.h |  4 ++--
>  2 files changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index aa2bbd14e0..77cf2db90f 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -622,7 +622,7 @@ static void create_v2m(VirtMachineState *vms)
>      vms->msi_controller = VIRT_MSI_CTRL_GICV2M;
>  }
>
> -static void create_gic(VirtMachineState *vms)
> +static void create_gic(VirtMachineState *vms, MemoryRegion *mem)
>  {
>      MachineState *ms = MACHINE(vms);
>      /* We create a standalone GIC */
> @@ -656,6 +656,12 @@ static void create_gic(VirtMachineState *vms)
>                               nb_redist_regions);
>          qdev_prop_set_uint32(vms->gic, "redist-region-count[0]", 
> redist0_count);
>
> +        if (!kvm_irqchip_in_kernel()) {
> +            object_property_set_link(OBJECT(vms->gic), "sysmem", OBJECT(mem),
> +                                     &error_fatal);
> +            qdev_prop_set_bit(vms->gic, "has-lpi", true);
> +        }
> +
>          if (nb_redist_regions == 2) {
>              uint32_t redist1_capacity =
>                      vms->memmap[VIRT_HIGH_GIC_REDIST2].size / 
> GICV3_REDIST_SIZE;
> @@ -2039,7 +2045,7 @@ static void machvirt_init(MachineState *machine)
>
>      virt_flash_fdt(vms, sysmem, secure_sysmem ?: sysmem);
>
> -    create_gic(vms);
> +    create_gic(vms, sysmem);
>
>      virt_cpu_post_init(vms, sysmem);
>
> diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
> index 34f8daa377..0613454975 100644
> --- a/target/arm/kvm_arm.h
> +++ b/target/arm/kvm_arm.h
> @@ -525,8 +525,8 @@ static inline const char *its_class_name(void)
>          /* KVM implementation requires this capability */
>          return kvm_direct_msi_enabled() ? "arm-its-kvm" : NULL;
>      } else {
> -        /* Software emulation is not implemented yet */
> -        return NULL;
> +        /* Software emulation based model */
> +        return "arm-gicv3-its";
>      }
>  }

This is OK as far as it goes, but I think we need to add the
versioned-machine support so that only "virt-6.1" and later get the
new ITS, and "virt-6.0" behave the same way (ie no ITS) as they did
in older QEMU versions.

thanks
-- PMM