[PATCH v2 033/144] KVM: selftests: Harden and comment XSS / KVM_SET_MSRS interaction

Sean Christopherson
2022-06-03T00:54:16Z

Assert that KVM_SET_MSRS returns '0' or '1' when setting XSS to a
non-zero value. The ioctl() itself should "succeed", its only the
setting of the XSS MSR that should fail/fault.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
tools/testing/selftests/kvm/x86_64/xss_msr_test.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/x86_64/xss_msr_test.c b/tools/testing/selftests/kvm/x86_64/xss_msr_test.c
index 7bd15f8a805c..a6abcb559e7c 100644
--- a/tools/testing/selftests/kvm/x86_64/xss_msr_test.c
+++ b/tools/testing/selftests/kvm/x86_64/xss_msr_test.c
@@ -53,7 +53,12 @@ int main(int argc, char *argv[])
for (i = 0; i < MSR_BITS; ++i) {
r = _vcpu_set_msr(vm, VCPU_ID, MSR_IA32_XSS, 1ull << i);

- TEST_ASSERT(r == 0 || xss_in_msr_list,
+ /*
+ * Setting a list of MSRs returns the entry that "faulted", or
+ * the last entry +1 if all MSRs were successfully written.
+ */
+ TEST_ASSERT(!r || r == 1, KVM_IOCTL_ERROR(KVM_SET_MSRS, r));
+ TEST_ASSERT(r != 1 || xss_in_msr_list,
"IA32_XSS was able to be set, but was not in save/restore list");
}

--
2.36.1.255.ge46751e96f-goog