[RFC] Support for Arm CCA VMs on Linux

[Jean-Philippe Brucker]

On Fri, Mar 03, 2023 at 09:54:47AM +0000, Suzuki K Poulose wrote:
> On 03/03/2023 09:46, Jean-Philippe Brucker wrote:
> > On Thu, Mar 02, 2023 at 07:12:24AM +0900, Itaru Kitayama wrote:
> > > > > I've tried your series in Real on CCA Host, but the KVM arch init
> > > > > emits an Invalid argument error and terminates.
> > 
> > This was the KVM_SET_ONE_REG for the SVE vector size. During my tests I
> > didn't enable SVE in the host but shrinkwrap enables more options.
> 
> Does the Qemu check for SVE capability on /dev/kvm ? For kvmtool, we
> changed to using the VM instance and that would prevent using SVE,
> until the RMM supports it.

Yes, QEMU does check the SVE cap on /dev/kvm. I can propose changing it or
complementing it with a VM check in my next version, it seems to work
(though I need to double-check the VM fd lifetime). Same goes for
KVM_CAP_STEAL_TIME, which I need to disable explicitly at the moment.

Thanks,
Jean

> 
> Suzuki
> 
> > 
> > Until we figure out support for SVE, disable it on the QEMU command-line
> > (similarly to '--disable-sve' needed for kvmtool boot):
> > 
> > 	-cpu host,sve=off
> > 
> > Thanks,
> > Jean
> 
>