Re: [PATCH] arm: xlnx-versal: fix virtio-mmio base address assignment

[Philippe Mathieu-Daudé]

Hi,

Please Cc the maintainers when posting your patch:

./scripts/get_maintainer.pl -f hw/arm/xlnx-versal-virt.c
Alistair Francis <alistair@alistair23.me> (maintainer:Xilinx ZynqMP and...)
"Edgar E. Iglesias" <edgar.iglesias@gmail.com> (maintainer:Xilinx ZynqMP
and...)
Peter Maydell <peter.maydell@linaro.org> (maintainer:Xilinx ZynqMP and...)
qemu-arm@nongnu.org (open list:Xilinx ZynqMP and...)

On 2/4/21 7:58 AM, schspa wrote:
> 
> At the moment the following QEMU command line triggers an assertion
> failure On xlnx-versal SOC:
>   qemu-system-aarch64 \
>       -machine xlnx-versal-virt -nographic -smp 2 -m 128 \
>       -fsdev local,id=shareid,path=${HOME}/work,security_model=none \
>       -device virtio-9p-device,fsdev=shareid,mount_tag=share \
>       -fsdev local,id=shareid1,path=${HOME}/Music,security_model=none \
>       -device virtio-9p-device,fsdev=shareid1,mount_tag=share1
> 
>   qemu-system-aarch64: ../migration/savevm.c:860:
>   vmstate_register_with_alias_id:
>   Assertion `!se->compat || se->instance_id == 0' failed.
> 
> This problem was fixed on arm virt platform in patch
>  
> https://lists.nongnu.org/archive/html/qemu-devel/2016-07/msg01119.html

Please use instead "in commit f58b39d2d5b ("virtio-mmio: format
transport base address in BusClass.get_dev_path")".

> It works perfectly on arm virt platform. but there is still there on
> xlnx-versal SOC.
> 
> The main difference between arm virt and xlnx-versal is they use
> different way to create virtio-mmio qdev. on arm virt, it calls
> sysbus_create_simple("virtio-mmio", base, pic[irq]); which will call
> sysbus_mmio_map internally and assign base address to subsys device
> mmio correctly. but xlnx-versal's implements won't do this.
> 
> However, xlnx-versal can't switch to sysbus_create_simple() to create
> virtio-mmio device. It's because xlnx-versal's cpu use
> VersalVirt.soc.fpd.apu.mr as it's memory. which is subregion of
> system_memory. sysbus_create_simple will add virtio to system_memory,
> which can't be accessed by cpu.
> 
> We can solve this by simply assign mmio[0].addr directly. makes
> virtio_mmio_bus_get_dev_path to produce correct unique device path.
> 
> Signed-off-by: schspa <schspa@gmail.com>
> ---
>  hw/arm/xlnx-versal-virt.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/arm/xlnx-versal-virt.c b/hw/arm/xlnx-versal-virt.c
> index 8482cd6196..87b92ec6c3 100644
> --- a/hw/arm/xlnx-versal-virt.c
> +++ b/hw/arm/xlnx-versal-virt.c
> @@ -490,6 +490,7 @@ static void create_virtio_regions(VersalVirt *s)
>          object_property_add_child(OBJECT(&s->soc), name, OBJECT(dev));
>          sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
>          sysbus_connect_irq(SYS_BUS_DEVICE(dev), 0, pic_irq);
> +        SYS_BUS_DEVICE(dev)->mmio[0].addr = base;

The proper API call is:

           sysbus_mmio_map(SYS_BUS_DEVICE(dev), 0, base);

>          mr = sysbus_mmio_get_region(SYS_BUS_DEVICE(dev), 0);
>          memory_region_add_subregion(&s->soc.mr_ps, base, mr);
>          g_free(name);
>