Re: [PATCH RFCv2 00/20] kvm/arm: Introduce a customizable aarch64 KVM host model

[Cornelia Huck]

On Thu, Dec 12 2024, Sebastian Ott <sebott@redhat.com> wrote:

> On Fri, 6 Dec 2024, Cornelia Huck wrote:
>> A respin/update on the aarch64 KVM cpu models. Also available at
>> gitlab.com/cohuck/qemu arm-cpu-model-rfcv2
>>
>> Find Eric's original cover letter below, so that I do not need to
>> repeat myself on the aspects that have not changed since RFCv1 :)
>>
>> Changes from RFCv1:
>>
>> Rebased on more recent QEMU (some adaptions in the register conversions
>> of the first few patches.)
>>
>> Based on feedback, I have removed the "custom" cpu model; instead, I
>> have added the new SYSREG_<REG>_<FIELD> properties to the "host" model.
>> This works well if you want to tweak anything that does not correspond
>> to the existing properties for the host model; however, if you e.g.
>> wanted to tweak sve, you have two ways to do so -- we'd probably either
>> want to check for conflicts, or just declare precedence. The kvm-specific
>> props remain unchanged, as they are orthogonal to this configuration.
>>
>> The cpu model expansion for the "host" model now dumps the new SYSREG_
>> properties in addition to the existing host model properties; this is a
>> bit ugly, but I don't see a good way on how to split this up.
>>
>
> I gave this a spin today and successfully migrated a VM between 2 similar
> machines that only differ in the DIC bit of the cache type register using:
>
>       -cpu host,SYSREG_CTR_EL0_DIC=0
>
> This allows me to get rid of my horrid qemu hacks to achieve the same.

Great, thanks for testing!