Re: [PATCH v5 03/11] target/arm: Restrict ARMv4 cpus to TCG accel

[Philippe Mathieu-Daudé]

On 1/30/21 7:54 PM, Peter Maydell wrote:
> On Sat, 30 Jan 2021 at 18:36, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
>>
>> Hi Peter,
>>
>> On 1/30/21 4:37 PM, Peter Maydell wrote:
>>> On Sat, 30 Jan 2021 at 01:52, Philippe Mathieu-Daudé <f4bug@amsat.org> 
>>> wrote:
>>>>
>>>> KVM requires a cpu based on (at least) the ARMv7 architecture.
>>>
>>> These days it requires ARMv8, because we dropped 32-bit host
>>> support, and all 64-bit host CPUs are v8.
>>
>> Oh, this comment is about the target, to justify it is pointless to
>> include pre-v7 target cpus/machines in a KVM-only binary.
>>
>> I'll update as:
>>
>> "KVM requires the target cpu based on (at least) the ARMv7
>> architecture."
> 
> KVM requires the target CPU to be at least ARMv8, because
> we only support the "host" cpu type, and all KVM host CPUs
> are v8, which means you can't pass a v7 CPU as the target CPU.
> (This used to not be true when we still supported running
> KVM on a v7 CPU like the Cortex-A15, in which case you could
> pass it to the guest.)

Indeed:

$ qemu-system-aarch64 -M xilinx-zynq-a9
qemu-system-aarch64: KVM is not supported for this guest CPU type
qemu-system-aarch64: kvm_init_vcpu: kvm_arch_init_vcpu failed (0):
Invalid argument