Re: [PATCH v2 2/5] hw/arm/virt: Add a control for the the highmem redistributors

[Andrew Jones]

On Sun, Oct 03, 2021 at 05:46:02PM +0100, Marc Zyngier wrote:
> Just like we can control the enablement of the highmem PCIe region
> using highmem_ecam, let's add a control for the highmem GICv3
> redistributor region.
> 
> Similarily to highmem_ecam, these redistributors are disabled when
> highmem is off.
> 
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
>  hw/arm/virt-acpi-build.c | 2 ++
>  hw/arm/virt.c            | 3 +++
>  include/hw/arm/virt.h    | 4 +++-
>  3 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> index d7bef0e627..f0d0b662b7 100644
> --- a/hw/arm/virt-acpi-build.c
> +++ b/hw/arm/virt-acpi-build.c
> @@ -792,6 +792,8 @@ void virt_acpi_build(VirtMachineState *vms, 
> AcpiBuildTables *tables)
>      acpi_add_table(table_offsets, tables_blob);
>      build_fadt_rev5(tables_blob, tables->linker, vms, dsdt);
>  
> +    vms->highmem_redists &= vms->highmem;
> +
>      acpi_add_table(table_offsets, tables_blob);
>      build_madt(tables_blob, tables->linker, vms);
>  
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index 8021d545c3..bcf58f677d 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -2053,6 +2053,8 @@ static void machvirt_init(MachineState *machine)
>  
>      virt_flash_fdt(vms, sysmem, secure_sysmem ?: sysmem);
>  
> +    vms->highmem_redists &= vms->highmem;
> +
>      create_gic(vms, sysmem);
>  
>      virt_cpu_post_init(vms, sysmem);
> @@ -2750,6 +2752,7 @@ static void virt_instance_init(Object *obj)
>      vms->gic_version = VIRT_GIC_VERSION_NOSEL;
>  
>      vms->highmem_ecam = !vmc->no_highmem_ecam;
> +    vms->highmem_redists = true;
>  
>      if (vmc->no_its) {
>          vms->its = false;
> diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
> index b461b8d261..787cc8a27d 100644
> --- a/include/hw/arm/virt.h
> +++ b/include/hw/arm/virt.h
> @@ -141,6 +141,7 @@ struct VirtMachineState {
>      bool secure;
>      bool highmem;
>      bool highmem_ecam;
> +    bool highmem_redists;
>      bool its;
>      bool tcg_its;
>      bool virt;
> @@ -187,7 +188,8 @@ static inline int 
> virt_gicv3_redist_region_count(VirtMachineState *vms)
>  
>      assert(vms->gic_version == VIRT_GIC_VERSION_3);
>  
> -    return MACHINE(vms)->smp.cpus > redist0_capacity ? 2 : 1;
> +    return (MACHINE(vms)->smp.cpus > redist0_capacity &&
> +            vms->highmem_redists) ? 2 : 1;

Wouldn't it be equivalent to just use vms->highmem here?

>  }
>  
>  #endif /* QEMU_ARM_VIRT_H */
> -- 
> 2.30.2
> 

Thanks,
drew