Re: [EXT] Re: QEMU+KVM on RISC-V + Hypervisor Extension

[Peter Maydell]

On Tue, 15 Mar 2022 at 12:29, Ralf Ramsauer
<ralf.ramsauer@oth-regensburg.de> wrote:
> I have no kernel specified in the guest, so I'd then expect to boot into
> an completely empty machine (besides the tiny startup stub in the MROM).
> However, I still get the exact same error as mentioned in my initial mail.
>
> Again, without "-enable-kvm", everything works as expected (i.e., I
> don't see any output, because there's basically no guest code to execute).

Well, you'll always be trying to execute something, even if it's
all-zeroes. I dunno what RISC-V does with its encodings, but you
typically either end up in an infinite loop of taking exceptions
(if all-0s isn't a valid instruction) or else you just execute
through all of guest RAM (if it is something similar to a no-op).
In the latter scenario it's quite plausible that the guest ends
up doing something KVM doesn't expect, such as trying to execute
from an area of the address space where there is no RAM, or a device.
If so, "return failure from VCPU_RUN and QEMU aborts" is what I
think I would expect to see.

If I were you I would try it with some actual guest code loaded
at a location where there is RAM...

-- PMM