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8b14c4d85d
To play nice with compilers generating AVX instructions, set CR4.OSXSAVE
and configure XCR0 by default when creating selftests vCPUs. Some distros
have switched gcc to '-march=x86-64-v3' by default, and while it's hard to
find a CPU which doesn't support AVX today, many KVM selftests fail with
==== Test Assertion Failure ====
lib/x86_64/processor.c:570: Unhandled exception in guest
pid=72747 tid=72747 errno=4 - Interrupted system call
Unhandled exception '0x6' at guest RIP '0x4104f7'
due to selftests not enabling AVX by default for the guest. The failure
is easy to reproduce elsewhere with:
$ make clean && CFLAGS='-march=x86-64-v3' make -j && ./x86_64/kvm_pv_test
E.g. gcc-13 with -march=x86-64-v3 compiles this chunk from selftests'
kvm_fixup_exception():
regs->rip = regs->r11;
regs->r9 = regs->vector;
regs->r10 = regs->error_code;
into this monstronsity (which is clever, but oof):
405313: c4 e1 f9 6e c8 vmovq %rax,%xmm1
405318: 48 89 68 08 mov %rbp,0x8(%rax)
40531c: 48 89 e8 mov %rbp,%rax
40531f: c4 c3 f1 22 c4 01 vpinsrq $0x1,%r12,%xmm1,%xmm0
405325: 49 89 6d 38 mov %rbp,0x38(%r13)
405329: c5 fa 7f 45 00 vmovdqu %xmm0,0x0(%rbp)
Alternatively, KVM selftests could explicitly restrict the compiler to
-march=x86-64-v2, but odds are very good that punting on AVX enabling will
simply result in tests that "need" AVX doing their own thing, e.g. there
are already three or so additional cleanups that can be done on top.
Reported-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Closes: https://lore.kernel.org/all/20240920154422.2890096-1-vkuznets@redhat.com
Reviewed-and-tested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20241003234337.273364-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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History
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| .. | ||
| crypto/chacha20-s390 | ||
| cxl | ||
| fault-injection | ||
| ktest | ||
| kunit | ||
| memblock | ||
| nvdimm | ||
| radix-tree | ||
| scatterlist | ||
| selftests | ||
| shared | ||
| vma | ||
| vsock | ||