On Fri, May 21, 2021 at 05:38:28PM +0000, David Matlack wrote:
> vm_get_max_gfn() casts vm->max_gfn from a uint64_t to an unsigned int,
> which causes the upper 32-bits of the max_gfn to get truncated.
>
> Nobody noticed until now likely because vm_get_max_gfn() is only used
> as a mechanism to create a memslot in an unused region of the guest
> physical address space (the top), and the top of the 32-bit physical
> address space was always good enough.
>
> This fix reveals a bug in memslot_modification_stress_test which was
> trying to create a dummy memslot past the end of guest physical memory.
> Fix that by moving the dummy memslot lower.
>
> Fixes: 52200d0d944e ("KVM: selftests: Remove duplicate guest mode handling")
> Reviewed-by: Venkatesh Srinivas <venkateshs@xxxxxxxxxxxx>
> Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
> ---
>
> v1 -> v2:
> - Added Venkatesh's R-b line.
> - Used PRIx64 to print uint64_t instead of %lx.
>
> tools/testing/selftests/kvm/include/kvm_util.h | 2 +-
> tools/testing/selftests/kvm/lib/kvm_util.c | 2 +-
> .../testing/selftests/kvm/lib/perf_test_util.c | 4 +++-
> .../kvm/memslot_modification_stress_test.c | 18 +++++++++++-------
> 4 files changed, 16 insertions(+), 10 deletions(-)
>
Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>
Thanks,
drew
