[PATCH v4 00/12] KVM: arm64: Support FEAT_LPA2 at hyp s1 and vm s2

[Marc Zyngier]

On Fri, 20 Oct 2023 16:22:29 +0100,
Ryan Roberts <ryan.roberts at arm.com> wrote:
> 
> On 20/10/2023 11:54, Marc Zyngier wrote:
> > Hi Ryan,
> > 
> > On Mon, 09 Oct 2023 19:49:56 +0100,
> > Ryan Roberts <ryan.roberts at arm.com> wrote:
> >>
> >> Hi All,
> >>
> >> This adds support for FEAT_LPA2 to KVM for both hypervisor stage 1 (for the
> >> nvhe/protected modes) and the vm stage 2 translation tables (for all modes).
> >> FEAT_LPA2 enables 52 bit PAs and VAs for 4KB and 16KB granules (note this is
> >> already supported for 64KB granules via the FEAT_LPA and FEAT_LVA extensions).
> >> The series does not include support for FEAT_LPA2 in the kernel stage 1. This
> >> support is provided separately by Ard Biesheuvel's series at [4]. The two series
> >> are mostly independent.
> >>
> >> This is a small update from v3, rebased onto v6.6-rc5 and incorporating some
> >> minor changes based on review comments from Oliver.
> >>
> >> NOTE: I've included my patch to update the range-based tlbi functions to work
> >> with LPA2 in this version, because KVM has started using range-based tlbi
> >> invalidation as of v6.6-rc1. I've done this in such a way that KVM-originated
> >> calls will use the LPA2 format if LPA2 is in use by KVM, but the
> >> kernel-originated calls are hardcoded to never use the LPA2 format. If merging
> >> with Ard's series, you will need to update the 2 calls to __flush_tlb_range_op()
> >> from __flush_tlb_range() appropriately.
> >>
> >>
> >> Testing
> >> =======
> >>
> >> Testing has been done exclusively on the FVP and covers my boot matrix tests
> >> and kvm selftests.
> >>
> >> The host/guest config boot matrix gives the same (expected) results as for the
> >> v3 submission; of 180 conifgs, 12 fail, and these are all due to attempting to
> >> load the host kernel into high memory which isn't expected to work until the
> >> kernel has FEAT_LPA2 support for its stage 1. (refer to v1 posting for details
> >> on the exact configs).
> >>
> >> KVM selftests have been enhanced to support P52V48 4K and 16K guest modes, and
> >> all tests have been run against a P48V48_4K host and a P52V52_4K host (a run
> >> takes about 10 hours on FVP, sigh, but I can test a few more host configs if
> >> useful).
> > 
> > Have you tried with the (brand new) "arm64_sw.hvhe=1" command-line
> > option, which enables VHE for the EL2 hypervisor only? I expect things
> > to work, but it would be good to make sure...
> 
> No, I haven't tried. I did notice it when I rebased but convinced myself that it
> doesn't affect the page table stuff. I'm happy to give it a spin once I've
> rebased to v6.7-rc1 though.

It does affect the page-table format (KVM_PTE_LEAF_ATTR_LO_S1_AP_RO
and co), so I'm taking the view that whatever is not tested doesn't
work.

Thanks for giving it a go!

	M.

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