From bf3f11581893494a5fb01eb87b99627edc2a85ff Mon Sep 17 00:00:00 2001 From: Vipin Sharma Date: Wed, 21 Sep 2022 23:24:51 -0700 Subject: [PATCH] KVM: selftests: Check result in hyperv_features for successful hypercalls Commit cc5851c6be86 ("KVM: selftests: Use exception fixup for #UD/#GP Hyper-V MSR/hcall tests") introduced a wrong guest assert in guest_hcall(). It is not checking the successful hypercall results and only checks the result when a fault happens. GUEST_ASSERT_2(!hcall->ud_expected || res == hcall->expect, hcall->expect, res); Correct the assertion by only checking results of the successful hypercalls. This issue was observed when this test started failing after building it in Clang. Above guest assert statement fails because "res" is not equal to "hcall->expect" when "hcall->ud_expected" is true. "res" gets some garbage value in Clang from the RAX register. In GCC, RAX is 0 because it using RAX for @output_address in the asm statement and resetting it to 0 before using it as output operand in the same asm statement. Clang is not using RAX for @output_address. Fixes: cc5851c6be86 ("KVM: selftests: Use exception fixup for #UD/#GP Hyper-V MSR/hcall tests") Signed-off-by: Vipin Sharma Suggested-by: Sean Christopherson Reviewed-by: Jim Mattson Reviewed-by: Vitaly Kuznetsov Link: https://lore.kernel.org/r/20220922062451.2927010-1-vipinsh@google.com [sean: wrap changelog at ~75 chars, move -EFAULT change to separate patch] Signed-off-by: Sean Christopherson --- tools/testing/selftests/kvm/x86_64/hyperv_features.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_features.c b/tools/testing/selftests/kvm/x86_64/hyperv_features.c index 79ab0152d2810..ad01868548f97 100644 --- a/tools/testing/selftests/kvm/x86_64/hyperv_features.c +++ b/tools/testing/selftests/kvm/x86_64/hyperv_features.c @@ -81,13 +81,13 @@ static void guest_hcall(vm_vaddr_t pgs_gpa, struct hcall_data *hcall) } vector = hypercall(hcall->control, input, output, &res); - if (hcall->ud_expected) + if (hcall->ud_expected) { GUEST_ASSERT_2(vector == UD_VECTOR, hcall->control, vector); - else + } else { GUEST_ASSERT_2(!vector, hcall->control, vector); + GUEST_ASSERT_2(res == hcall->expect, hcall->expect, res); + } - GUEST_ASSERT_2(!hcall->ud_expected || res == hcall->expect, - hcall->expect, res); GUEST_DONE(); } -- 2.30.2