On 06/09/2018 01:19, Liran Alon wrote:
> Hi,
>
> I wanted to raise an issue that the kvm-unit-test added by commit 728e71ee4573 ("x86: add UMIP test")
> always fails when UMIP is being emulated by KVM (when CPU don't support UMIP).
>
> This happens because one of the things the unit-test does is to verify SMSW executed from Ring3
> while UMIP=1, should raise a #GP. However, if UMIP is emulated by KVM, this won't happen because
> there is no way to cause SMSW to cause a #VMExit to trigger SMSW emulator code in KVM.
>
> This is actually a known limitation of the KVM UMIP emulation feature introduced by commit
> 0367f205a3b7 ("KVM: vmx: add support for emulating UMIP") and it is well documented in commit message.
>
> Considering the above, do we really want to keep the SMSW UMIP=1,CPL=3 test? Or should I remove it
> from kvm-unit-tests? As this test is known to always fail...
> (Which is confusing when running all x86 tests to verify a new patch)
Yeah, I added that test because I was using the test to implement UMIP
in QEMU, too. But it's probably best to comment it out.
Paolo
