Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> writes:
> Sean Christopherson <seanjc@xxxxxxxxxx> writes:
>
>> On Fri, Oct 15, 2021, Vitaly Kuznetsov wrote:
>>> Several selftests (memslot_modification_stress_test, kvm_page_table_test,
>>> dirty_log_perf_test,.. ) which rely on vm_get_max_gfn() started to fail
>>> since commit ef4c9f4f65462 ("KVM: selftests: Fix 32-bit truncation of
>>> vm_get_max_gfn()") on AMD EPYC 7401P:
>>>
>>> ./tools/testing/selftests/kvm/demand_paging_test
>>> Testing guest mode: PA-bits:ANY, VA-bits:48, 4K pages
>>> guest physical test memory offset: 0xffffbffff000
>>
>> This look a lot like the signature I remember from the original bug[1]. I assume
>> you're hitting the magic HyperTransport region[2]. I thought that was fixed, but
>> the hack-a-fix for selftests never got applied[3].
>>
>> [1] https://lore.kernel.org/lkml/20210623230552.4027702-4-seanjc@xxxxxxxxxx/
>
> Hey,
>
> it seems I'm only three months late to the party!
>
>> [2] https://lkml.kernel.org/r/7e3a90c0-75a1-b8fe-dbcf-bda16502ace9@xxxxxxx
>> [3] https://lkml.kernel.org/r/20210805105423.412878-1-pbonzini@xxxxxxxxxx
>>
>
> This patch helps indeed
FWIW, 'access_tracking_perf_test' remains broken even after the patch is
applied:
# ./access_tracking_perf_test
Testing guest mode: PA-bits:ANY, VA-bits:48, 4K pages
guest physical test memory offset: 0xfffcbffff000
Populating memory : 3.858448918s
Writing to populated memory : 0.937319626s
Reading from populated memory : 0.003073207s
==== Test Assertion Failure ====
lib/kvm_util.c:1382: false
pid=6422 tid=6425 errno=4 - Interrupted system call
1 0x000000000040667d: addr_gpa2hva at kvm_util.c:1382
2 (inlined by) addr_gpa2hva at kvm_util.c:1376
3 (inlined by) addr_gva2hva at kvm_util.c:2245
4 0x0000000000402909: lookup_pfn at access_tracking_perf_test.c:98
5 (inlined by) mark_vcpu_memory_idle at access_tracking_perf_test.c:152
6 (inlined by) vcpu_thread_main at access_tracking_perf_test.c:232
7 0x00007fd02d1cb431: ?? ??:0
8 0x00007fd02d0f9912: ?? ??:0
No vm physical memory at 0xfcbffff000
(and my cpuid hack reducing guest physical address space by half doesn't
seem to help either)
--
Vitaly
