Re: [PATCH v7 09/10] hw/arm/virt: add ITS support in virt GIC

[Igor Mammedov]

On Thu,  5 Aug 2021 18:30:01 -0400
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>
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  hw/arm/virt.c         | 28 ++++++++++++++++++++++++++--
>  include/hw/arm/virt.h |  2 ++
>  target/arm/kvm_arm.h  |  4 ++--
>  3 files changed, 30 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index 81eda46b0b..99cf4f9dbd 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -583,6 +583,12 @@ static void create_its(VirtMachineState *vms)
>      const char *itsclass = its_class_name();
>      DeviceState *dev;
>  
> +    if (!strcmp(itsclass, "arm-gicv3-its")) {
> +        if (!vms->tcg_its) {
> +            itsclass = NULL;
> +        }
> +    }
> +
>      if (!itsclass) {
>          /* Do nothing if not supported */
>          return;
> @@ -620,7 +626,7 @@ 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 */
> @@ -654,6 +660,14 @@ 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()) {
> +            if (vms->tcg_its) {
> +                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;
> @@ -2043,7 +2057,7 @@ 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);
>  
> @@ -2746,6 +2760,12 @@ static void virt_instance_init(Object *obj)
>      } else {
>          /* Default allows ITS instantiation */
>          vms->its = true;
> +
> +        if (vmc->no_tcg_its) {
> +            vms->tcg_its = false;
> +        } else {
> +            vms->tcg_its = true;
> +        }
>      }
>  
>      /* Default disallows iommu instantiation */
> @@ -2795,8 +2815,12 @@ DEFINE_VIRT_MACHINE_AS_LATEST(6, 1)
>  
>  static void virt_machine_6_0_options(MachineClass *mc)
>  {
> +    VirtMachineClass *vmc = VIRT_MACHINE_CLASS(OBJECT_CLASS(mc));
> +
>      virt_machine_6_1_options(mc);
>      compat_props_add(mc->compat_props, hw_compat_6_0, hw_compat_6_0_len);
> +    /* qemu ITS was introduced with 6.1 */
> +    vmc->no_tcg_its = true;

given it's not going to be in 6.1, shouldn't it be moved to
virt_machine_6_1_options() with updated comment?

>  }
>  DEFINE_VIRT_MACHINE(6, 0)
>  
> diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
> index 9661c46699..b461b8d261 100644
> --- a/include/hw/arm/virt.h
> +++ b/include/hw/arm/virt.h
> @@ -120,6 +120,7 @@ struct VirtMachineClass {
>      MachineClass parent;
>      bool disallow_affinity_adjustment;
>      bool no_its;
> +    bool no_tcg_its;
>      bool no_pmu;
>      bool claim_edge_triggered_timers;
>      bool smbios_old_sys_ver;
> @@ -141,6 +142,7 @@ struct VirtMachineState {
>      bool highmem;
>      bool highmem_ecam;
>      bool its;
> +    bool tcg_its;
>      bool virt;
>      bool ras;
>      bool mte;
> 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";
>      }
>  }
>