Directly compare the expected versus observed hypercall instructions when
verifying that KVM patched in the native hypercall (FIX_HYPERCALL_INSN
quirk enabled). gcc rightly complains that doing a 4-byte memcpy() with
an "unsigned char" as the source generates an out-of-bounds accesses.
Alternatively, "exp" and "obs" could be declared as 3-byte arrays, but
there's no known reason to copy locally instead of comparing directly.
In function ‘assert_hypercall_insn’,
inlined from ‘guest_main’ at x86_64/fix_hypercall_test.c:91:2:
x86_64/fix_hypercall_test.c:63:9: error: array subscript ‘unsigned int[0]’
is partly outside array bounds of ‘unsigned char[1]’ [-Werror=array-bounds]
63 | memcpy(&exp, exp_insn, sizeof(exp));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
x86_64/fix_hypercall_test.c: In function ‘guest_main’:
x86_64/fix_hypercall_test.c:42:22: note: object ‘vmx_hypercall_insn’ of size 1
42 | extern unsigned char vmx_hypercall_insn;
| ^~~~~~~~~~~~~~~~~~
x86_64/fix_hypercall_test.c:25:22: note: object ‘svm_hypercall_insn’ of size 1
25 | extern unsigned char svm_hypercall_insn;
| ^~~~~~~~~~~~~~~~~~
In function ‘assert_hypercall_insn’,
inlined from ‘guest_main’ at x86_64/fix_hypercall_test.c:91:2:
x86_64/fix_hypercall_test.c:64:9: error: array subscript ‘unsigned int[0]’
is partly outside array bounds of ‘unsigned char[1]’ [-Werror=array-bounds]
64 | memcpy(&obs, obs_insn, sizeof(obs));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
x86_64/fix_hypercall_test.c: In function ‘guest_main’:
x86_64/fix_hypercall_test.c:25:22: note: object ‘svm_hypercall_insn’ of size 1
25 | extern unsigned char svm_hypercall_insn;
| ^~~~~~~~~~~~~~~~~~
x86_64/fix_hypercall_test.c:42:22: note: object ‘vmx_hypercall_insn’ of size 1
42 | extern unsigned char vmx_hypercall_insn;
| ^~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make: *** [../lib.mk:135: tools/testing/selftests/kvm/x86_64/fix_hypercall_test] Error 1
Fixes: 6c2fa8b20d ("selftests: KVM: Test KVM_X86_QUIRK_FIX_HYPERCALL_INSN")
Cc: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Message-Id: <20220928233652.783504-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
394265079b