On 2/9/21 8:48 AM, Sean Christopherson wrote: > 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. Looks great to me. One nit: to a me, "reclaim" is different than "free". Reclaim is a specific operation where a page is taken from one user and reclaimed for other use. "Free" is the more general case (which includes reclaim) when a physical page is no longer being used (because the user is done *or* had the page reclaimed) and may be either used by someone else or put in a free pool. I *think* this is actually a "free" operation, rather than a "reclaim". IIRC, this code gets used at munmap().
