Re: [PATCH 0/2] 52-bit VA guest mode ID support

[Fuad Tabba]

Hi Itaru,


On Tue, 25 Aug 2026 at 22:18, Itaru Kitayama <itaru.kitayama@xxxxxxxxxxx> wrote:
>
> This patch series extends the arm64 KVM selftest framework
> to support 52-bit guest virtual address (VA) modes in addition to
> the existing 52-bit physical address (PA) configurations.
> The motivation is to enable validation of LPA2 guest memory-management
> behaviour in configurations that use a 52-bit VA space.
> While the selftest framework already supports testing 52-bit PA
> configurations, it lacks the ability to exercise guests running with
> 52-bit virtual addresses, leaving part of the LPA2 functionality untested.

The series adds three 52-bit VA guest modes, but nothing in tree maps
a guest VA high enough to use them. The mode-iterating tests map at a
fixed low GVA, so pgd_index() returns 0 and only the first entry of
the top level is ever used.

What do you expect the modes to catch as they stand? The allocators
already take a minimum GVA, so mapping high in one of those tests
looks like a small change.

> To address this, the series introduces new guest modes for 52-bit VA
> operation, adds five-level page table support where required, and
> performs runtime detection of host 52-bit VA capability so that
> LPA2-enabled guest VA tests are executed only on supported systems.
>
> Testing:
>
> Built and tested on arm64.
> Verified on QEMU with a V52-capable guest configuration.
> Confirmed correct operation of high virtual address mappings by
> exercising guest memory accesses in the 52-bit VA range.

I could not reproduce "exercising guest memory accesses in the 52-bit
VA range" with anything in tree either. Could you say which test you
ran, which guest modes, and on what?

Thanks,
/fuad

> Signed-off-by: Itaru Kitayama <itaru.kitayama@xxxxxxxxxxx>
> Reviewed-by: Takayuki Okamoto <tokamoto@xxxxxxxxxxx>
> ---
> Itaru Kitayama (2):
>       KVM: selftest: arm64: Support 5-level paging in stage 1 translation table
>       KVM: selftests: arm64: Add 52-bit VA guest modes
>
>  .../selftests/kvm/include/arm64/processor.h        |  2 +
>  tools/testing/selftests/kvm/include/kvm_util.h     |  3 +
>  tools/testing/selftests/kvm/lib/arm64/processor.c  | 87 ++++++++++++++++++++--
>  tools/testing/selftests/kvm/lib/guest_modes.c      |  5 ++
>  tools/testing/selftests/kvm/lib/kvm_util.c         | 11 +++
>  5 files changed, 103 insertions(+), 5 deletions(-)
> ---
> base-commit: 8d3ae59288f1e7d58d76558a6ee96d533bc5019f
> change-id: 20260825-arm64-52bit-va-32f1f4cd050d
>
> Best regards,
> --
> Itaru Kitayama <itaru.kitayama@xxxxxxxxxxx>
>