Re: [RFC PATCH v4 04/26] x86/sgx: Add SGX_CHILD_PRESENT hardware error code

Sean Christopherson
2021-02-09T16:51:21Z

On Tue, Feb 09, 2021, Dave Hansen wrote:
> On 2/8/21 2:54 AM, Kai Huang wrote:
> ...
> > Add SGX_CHILD_PRESENT for use by SGX virtualization to assert EREMOVE
> > failures are expected, but only due to SGX_CHILD_PRESENT.
>
> This paragraph broke my brain when I read it. How about:
>
> Add a definition of SGX_CHILD_PRESENT. It will be used
> exclusively by the SGX virtualization driver to suppress EREMOVE
> warnings.

Maybe worth clarifying that the driver isn't suppressing warnings willy-nilly?
And the error code isn't about suppressing warnings, it's about identifying the
expected EREMOVE failure scenario. The patch that creates the separate helper
for doing EREMOVE without the WARN is what provides the suppression mechanism.

Something like this?

Add a definition of SGX_CHILD_PRESENT. It will be used exclusively by
the SGX virtualization driver to handle recoverable EREMOVE errors when
saniziting EPC pages after they are reclaimed from a guest.