Re: [PATCH v6 0/7] KVM: arm64: nv: Implement nested stage-2 reverse map

[Marc Zyngier]

On Thu, 17 Sep 2026 07:51:19 +0100,
Itaru Kitayama <itaru.kitayama@xxxxxxxxxxx> wrote:
> 
> On Wed, Sep 16, 2026 at 08:08:20AM +0100, Marc Zyngier wrote:
> > On Wed, 16 Sep 2026 00:27:22 +0100,
> > Itaru Kitayama <itaru.kitayama@xxxxxxxxxxx> wrote:
> > > 
> > > On Wed, Sep 16, 2026 at 12:22:30AM +0100, Wei-Lin Chang wrote:
> > > > On Wed, Sep 16, 2026 at 06:49:57AM +0900, Itaru Kitayama wrote:
> > > > > On Tue, Sep 15, 2026 at 04:42:58PM +0100, Wei-Lin Chang wrote:
> > > > > > Hi,
> > > > > > 
> > > > > > This is v6 of optimizing the shadow s2 mmu unmapping during MMU
> > > > > > notifiers.
> > > > > > 
> > > > > > This version fixes a few issues, and adds Marc's space optimization
> > > > > > for kvm_guest_s2_mapping [1]. Please see the changelog for the details.
> > > > > > 
> > > > > > Tested by booting L3, and running in-kernel targetted tests described
> > > > > > in [2]. v5 got some tested-by's from Itaru and Wang (thanks), I didn't
> > > > > > carry them over since some bugs fixed in v6 are non-obvious. Some
> > > > > > retest would be much appreciated!
> > > > > 
> > > > > How did you boot into L3, with KVM selftest or recrusively boot on HW?
> > > > 
> > > > I just recrusively booted VMs on hardware. :)
> > > 
> > > Good. Then I actually tried that on Grace CPUs, but letting L1 boot 
> > > with nested mode did not print "VHE+NV2" KVM init log in dmesg, thus not
> > > able to boot L3. Do I need to add other than kvm.arm-mode=nested to command line?
> > 
> > kvm-arm.mode=nested, as documented. That also puts in perspective your
> > TB tag on the whole series...
> 
> Yes. Using kvmtool's --nested option did not bring vCPU with the VHE+NV2 boot
> log. The Host kernel is Wei-Lin's version 6 booted on Grace CPUs, and
> the guest kernel is today's kvmarm/fixes plus Wei-Lin's shadow stage 2 ptdump fix.

What have you tested exactly? If you're not able to boot a working L1
guest as a NV2 hypervisor, you're probably doing something wrong.

	M.

-- 
Without deviation from the norm, progress is not possible.