On Thu, May 20, 2021 at 09:26:54PM +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.
s/top/bottom/?
Looks right.. thanks for fixing it!
>
> 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.
Would it be better to split the different fixes?
>
> Fixes: 52200d0d944e ("KVM: selftests: Remove duplicate guest mode handling")
> Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
> ---
> 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 | 2 +-
> .../kvm/memslot_modification_stress_test.c | 18 +++++++++++-------
> 4 files changed, 14 insertions(+), 10 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> index 84982eb02b29..5d9b35d09251 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> @@ -303,7 +303,7 @@ bool vm_is_unrestricted_guest(struct kvm_vm *vm);
>
> unsigned int vm_get_page_size(struct kvm_vm *vm);
> unsigned int vm_get_page_shift(struct kvm_vm *vm);
> -unsigned int vm_get_max_gfn(struct kvm_vm *vm);
> +uint64_t vm_get_max_gfn(struct kvm_vm *vm);
> int vm_get_fd(struct kvm_vm *vm);
>
> unsigned int vm_calc_num_guest_pages(enum vm_guest_mode mode, size_t size);
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index 1af1009254c4..aeffbb1e7c7d 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -2058,7 +2058,7 @@ unsigned int vm_get_page_shift(struct kvm_vm *vm)
> return vm->page_shift;
> }
>
> -unsigned int vm_get_max_gfn(struct kvm_vm *vm)
> +uint64_t vm_get_max_gfn(struct kvm_vm *vm)
> {
> return vm->max_gfn;
> }
> diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c
> index 81490b9b4e32..ed4424ed26d6 100644
> --- a/tools/testing/selftests/kvm/lib/perf_test_util.c
> +++ b/tools/testing/selftests/kvm/lib/perf_test_util.c
> @@ -80,7 +80,7 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int vcpus,
> */
> TEST_ASSERT(guest_num_pages < vm_get_max_gfn(vm),
> "Requested more guest memory than address space allows.\n"
> - " guest pages: %lx max gfn: %x vcpus: %d wss: %lx]\n",
> + " guest pages: %lx max gfn: %lx vcpus: %d wss: %lx]\n",
If to fix it, maybe start to use PRIu64 (and include inttypes.h)?
Thanks,
--
Peter Xu
