Hi Itaru, On Tue, 8 Sept 2026 at 03:18, Itaru Kitayama <[email protected]> wrote: > > Hi Fuad, > On Fri, Sep 04, 2026 at 09:14:36AM +0100, Fuad Tabba wrote: > > On Tue, 25 Aug 2026 at 22:18, Itaru Kitayama <[email protected]> > > 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. > > I think at least a 4KB page is allocated for the level -1 translation table, > and entry 0 is populated with a Table descriptor pointing to the level 0 > translation > table. But, no it does not test a nonzero top-level index.
Right, that's the gap. Every mode-iterating test maps at a fixed low GVA (0xc0000000), so the new modes only ever fill entry 0 of the top table. If the series adds the modes, it should add a test that drives a VA into the 52-bit range. > > > > > 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? > > I just in guest_code() of existing one of the kselftests, mapped and > accessed a page at 1ULL << 49 using virt_pg_map() and on QEMU TCG mode > as I don't currently have access to the machines LPA and LPA2 features. That test is what the series needs, and you've already written it. Folding a mode-iterating version in tree would exercise the modes and make the cover letter's "52-bit VA range" line reproducible. It runs under TCG, so no LPA2 hardware needed. Cheers, /fuad > Thanks, > Itaru. > > > > Thanks, > > /fuad > > > > > Signed-off-by: Itaru Kitayama <[email protected]> > > > Reviewed-by: Takayuki Okamoto <[email protected]> > > > --- > > > 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 <[email protected]> > > >
