Re: [PATCH v4] virtio-mmio: improve virtio-mmio get_dev_path alog

[Shi Schspa <schspa@gmail.com>]

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Thank you very much.

Best regards.


Peter Maydell <peter.maydell@linaro.org> 于2021年3月5日周五 下午7:57写道：

> On Thu, 25 Feb 2021 at 05:36, schspa <schspa@gmail.com> 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 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.
> >
> > Besides, xlnx-versal can't add sysbus_mmio_map api call too, because
> > this will add memory region to system_memory, and it can't be added
> > to VersalVirt.soc.fpd.apu.mr again.
> >
> > We can solve this by assign correct base address offset on dev_path.
> >
> > This path was test on aarch64 virt & xlnx-versal platform.
> >
> > Signed-off-by: schspa <schspa@gmail.com>
> > ---
>
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
>
> Applied to target-arm.next, thanks (unless MST would rather it
> go in via another route).
>
> -- PMM
>

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