Re: [Qemu-devel] [RFC 4/7] enable fw_cfg dma for arm virt

[Peter Maydell]

On 21 July 2015 at 17:03, Marc Marí <address@hidden> wrote:
> From: Gerd Hoffmann <address@hidden>
>
> Signed-off-by: Gerd Hoffmann <address@hidden>
> ---
>  docs/specs/fw_cfg.txt |  6 ++++++
>  hw/arm/virt.c         | 11 ++++++++---
>  2 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/docs/specs/fw_cfg.txt b/docs/specs/fw_cfg.txt
> index 64d9192..eac83a1 100644
> --- a/docs/specs/fw_cfg.txt
> +++ b/docs/specs/fw_cfg.txt
> @@ -167,6 +167,12 @@ If a partial transfer happened before an error occured 
> the address and
>  length registers indicate how much data has been transfered
>  successfully.
>
> +== Register Locations ==
> +
> +=== arm ===
> +
> +classic fw_cfg base + 16
> +
>  = Host-side API =
>
>  The following functions are available to the QEMU programmer for adding
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index 374660c..d05f6a4 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -606,13 +606,13 @@ static void create_flash(const VirtBoardInfo *vbi)
>      g_free(nodename);
>  }
>
> -static void create_fw_cfg(const VirtBoardInfo *vbi)
> +static void create_fw_cfg(AddressSpace *as, const VirtBoardInfo *vbi)
>  {
>      hwaddr base = vbi->memmap[VIRT_FW_CFG].base;
>      hwaddr size = vbi->memmap[VIRT_FW_CFG].size;
>      char *nodename;
>
> -    fw_cfg_init_mem_wide(base + 8, base, 8, 0, NULL);
> +    fw_cfg_init_mem_wide(base + 8, base, 8, 16, as);
>
>      nodename = g_strdup_printf("/address@hidden" PRIx64, base);
>      qemu_fdt_add_subnode(vbi->fdt, nodename);

Don't we need to also update the device tree (and the spec for
that!) to indicate that we're providing a with-DMA fw-cfg
device ?

> @@ -800,6 +800,7 @@ static void machvirt_init(MachineState *machine)
>      VirtGuestInfoState *guest_info_state = g_malloc0(sizeof 
> *guest_info_state);
>      VirtGuestInfo *guest_info = &guest_info_state->info;
>      char **cpustr;
> +    AddressSpace *as = NULL;
>
>      if (!cpu_model) {
>          cpu_model = "cortex-a15";
> @@ -837,6 +838,10 @@ static void machvirt_init(MachineState *machine)
>          }
>          cpuobj = object_new(object_class_get_name(oc));
>
> +        if (!as) {
> +            as = CPU(cpuobj)->as;
> +        }

Is this really the right AddressSpace to use? Fishing
around in the CPU object seems a bit dubious...

thanks
-- PMM