Re: [PATCH] KVM: selftests: page_table_test: fix calculation of guest_test_phys_mem

[Paolo Bonzini]

On 11/26/21 16:28, Maciej S. Szmigiero wrote:
> From: "Maciej S. Szmigiero" <maciej.szmigiero@xxxxxxxxxx>
>
> A kvm_page_table_test run with its default settings fails on VMX due to
> memory region add failure:
> > ==== Test Assertion Failure ====
> >   lib/kvm_util.c:952: ret == 0
> >   pid=10538 tid=10538 errno=17 - File exists
> >      1  0x00000000004057d1: vm_userspace_mem_region_add at kvm_util.c:947
> >      2  0x0000000000401ee9: pre_init_before_test at kvm_page_table_test.c:302
> >      3   (inlined by) run_test at kvm_page_table_test.c:374
> >      4  0x0000000000409754: for_each_guest_mode at guest_modes.c:53
> >      5  0x0000000000401860: main at kvm_page_table_test.c:500
> >      6  0x00007f82ae2d8554: ?? ??:0
> >      7  0x0000000000401894: _start at ??:?
> >   KVM_SET_USER_MEMORY_REGION IOCTL failed,
> >   rc: -1 errno: 17
> >   slot: 1 flags: 0x0
> >   guest_phys_addr: 0xc0000000 size: 0x40000000
>
> This is because the memory range that this test is trying to add
> (0x0c0000000 - 0x100000000) conflicts with LAPIC mapping at 0x0fee00000.
>
> Looking at the code it seems that guest_test_*phys*_mem variable gets
> mistakenly overwritten with guest_test_*virt*_mem while trying to adjust
> the former for alignment.
> With the correct variable adjusted this test runs successfully.
>
> Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx>
> ---
>   tools/testing/selftests/kvm/kvm_page_table_test.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/kvm/kvm_page_table_test.c b/tools/testing/selftests/kvm/kvm_page_table_test.c
> index 3836322add00..ba1fdc3dcf4a 100644
> --- a/tools/testing/selftests/kvm/kvm_page_table_test.c
> +++ b/tools/testing/selftests/kvm/kvm_page_table_test.c
> @@ -280,7 +280,7 @@ static struct kvm_vm *pre_init_before_test(enum vm_guest_mode mode, void *arg)
>   #ifdef __s390x__
>   	alignment = max(0x100000, alignment);
>   #endif
> -	guest_test_phys_mem = align_down(guest_test_virt_mem, alignment);
> +	guest_test_phys_mem = align_down(guest_test_phys_mem, alignment);
>   
>   	/* Set up the shared data structure test_args */
>   	test_args.vm = vm;

Queued, thanks.

Paolo