Re: [PATCH 0/4] KVM: selftests: Introduce VM_MODE_PXXV48_4K

[Andrew Jones]

On Wed, Aug 28, 2019 at 01:51:06PM +0200, Andrew Jones wrote:
> On Tue, Aug 27, 2019 at 09:10:11PM +0800, Peter Xu wrote:
> > The work is based on Thomas's s390 port for dirty_log_test.
> > 
> > This series originates from "[PATCH] KVM: selftests: Detect max PA
> > width from cpuid" [1] and one of Drew's comments - instead of keeping
> > the hackish line to overwrite guest_pa_bits all the time, this series
> > introduced the new mode VM_MODE_PXXV48_4K for x86_64 platform.
> > 
> > The major issue is that even all the x86_64 kvm selftests are
> > currently using the guest mode VM_MODE_P52V48_4K, many x86_64 hosts
> > are not using 52 bits PA (and in most cases, far less).  If with luck
> > we could be having 48 bits hosts, but it's more adhoc (I've observed 3
> > x86_64 systems, they are having different PA width of 36, 39, 48).  I
> > am not sure whether this is happening to the other archs as well, but
> > it probably makes sense to bring the x86_64 tests to the real world on
> > always using the correct PA bits.
> > 
> > A side effect of this series is that it will also fix the crash we've
> > encountered on Xeon E3-1220 as mentioned [1] due to the
> > differenciation of PA width.
> > 
> > With [1], we've observed AMD host issues when with NPT=off.  However a
> > funny fact is that after I reworked into this series, the tests can
> > instead pass on both NPT=on/off.  It could be that the series changes
> > vm->pa_bits or other fields so something was affected.  I didn't dig
> > more on that though, considering we should not lose anything.
> > 
> > Any kind of smoke test would be greatly welcomed (especially on s390
> > or ARM).  Same to comments.  Thanks,
> > 
> 
> The patches didn't apply cleanly for me on 9e8312f5e160, but once I got
> them applied I was able to run the aarch64 tests.

Oh, and after fixing 2/4 (vm->pa_bits) to fix compilation on aarch64 as
pointed out on that patch.

> 
> > [1] https://lkml.org/lkml/2019/8/26/141
> > 
> > Peter Xu (4):
> >   KVM: selftests: Move vm type into _vm_create() internally
> >   KVM: selftests: Create VM earlier for dirty log test
> >   KVM: selftests: Introduce VM_MODE_PXXV48_4K
> >   KVM: selftests: Remove duplicate guest mode handling
> > 
> >  tools/testing/selftests/kvm/dirty_log_test.c  | 78 +++++--------------
> >  .../testing/selftests/kvm/include/kvm_util.h  | 17 +++-
> >  .../selftests/kvm/lib/aarch64/processor.c     |  3 +
> >  tools/testing/selftests/kvm/lib/kvm_util.c    | 77 ++++++++++++++----
> >  .../selftests/kvm/lib/x86_64/processor.c      |  8 +-
> >  5 files changed, 107 insertions(+), 76 deletions(-)
> > 
> > -- 
> > 2.21.0
> >
> 
> Thanks,
> drew