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

[Ryan Roberts]

On 23/10/2023 10:42, Marc Zyngier wrote:
> 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!

ACk to this and the other emails you sent today on this topic. Thanks for the
fast responses - I'll come back to you on the TLBI benchmarks in a couple of
weeks if they show anything that means we have to make a decision other than
what we already discussed. Otherwise I'll be 4ish weeks when I post on top of
v6.7-rc1.

Thanks,
Ryan


> 
> 	M.
>