On 3/13/19 3:19 PM, Sean Christopherson wrote:
> ...so that the test doesn't end up in an infinite loop if it fails for
> whatever reason, e.g. SHUTDOWN due to gcc inserting stack canary code
> into ucall() and attempting to derefence a null segment.
You fix passed on my box. Before I ack it, could you share the failure
case (i.e. the steps to reproduce infinite loop) mentioned above?
>
> Fixes: ca359066889f7 ("kvm: selftests: add cr4_cpuid_sync_test")
> Cc: Wei Huang <wei@xxxxxxxxxx>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> ---
> .../kvm/x86_64/cr4_cpuid_sync_test.c | 35 ++++++++++---------
> 1 file changed, 19 insertions(+), 16 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c b/tools/testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c
> index d503a51fad30..7c2c4d4055a8 100644
> --- a/tools/testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c
> @@ -87,22 +87,25 @@ int main(int argc, char *argv[])
> while (1) {
> rc = _vcpu_run(vm, VCPU_ID);
>
> - if (run->exit_reason == KVM_EXIT_IO) {
> - switch (get_ucall(vm, VCPU_ID, &uc)) {
> - case UCALL_SYNC:
> - /* emulate hypervisor clearing CR4.OSXSAVE */
> - vcpu_sregs_get(vm, VCPU_ID, &sregs);
> - sregs.cr4 &= ~X86_CR4_OSXSAVE;
> - vcpu_sregs_set(vm, VCPU_ID, &sregs);
> - break;
> - case UCALL_ABORT:
> - TEST_ASSERT(false, "Guest CR4 bit (OSXSAVE) unsynchronized with CPUID bit.");
> - break;
> - case UCALL_DONE:
> - goto done;
> - default:
> - TEST_ASSERT(false, "Unknown ucall 0x%x.", uc.cmd);
> - }
> + TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
> + "Unexpected exit reason: %u (%s),\n",
> + run->exit_reason,
> + exit_reason_str(run->exit_reason));
> +
> + switch (get_ucall(vm, VCPU_ID, &uc)) {
> + case UCALL_SYNC:
> + /* emulate hypervisor clearing CR4.OSXSAVE */
> + vcpu_sregs_get(vm, VCPU_ID, &sregs);
> + sregs.cr4 &= ~X86_CR4_OSXSAVE;
> + vcpu_sregs_set(vm, VCPU_ID, &sregs);
> + break;
> + case UCALL_ABORT:
> + TEST_ASSERT(false, "Guest CR4 bit (OSXSAVE) unsynchronized with CPUID bit.");
> + break;
> + case UCALL_DONE:
> + goto done;
> + default:
> + TEST_ASSERT(false, "Unknown ucall 0x%x.", uc.cmd);
> }
> }
>
>
