On Wed, Jul 07, 2021 at 02:20:04PM -0700, Reinette Chatre wrote: > Hi Jarkko, > > On 7/7/2021 1:50 PM, Jarkko Sakkinen wrote: > > On Wed, Jul 07, 2021 at 08:02:42AM -0700, Reinette Chatre wrote: > > > Hi Jarkko, > > > > > > On 7/7/2021 2:17 AM, Jarkko Sakkinen wrote: > > > > On Tue, Jul 06, 2021 at 05:10:38PM -0700, Reinette Chatre wrote: > > > > > Hi Jarkko, > > > > > > > > > > On 7/6/2021 4:50 PM, Jarkko Sakkinen wrote: > > > > > > On Tue, Jul 06, 2021 at 11:34:54AM -0700, Reinette Chatre wrote: > > > > > > > Hi Jarkko, > > > > > > > > > > > > > > On 7/5/2021 7:36 AM, Jarkko Sakkinen wrote: > > > > > > > > Create a heap for the test enclave, which has the same size as all > > > > > > > > available Enclave Page Cache (EPC) pages in the system. This will guarantee > > > > > > > > that all test_encl.elf pages *and* SGX Enclave Control Structure (SECS) > > > > > > > > have been swapped out by the page reclaimer during the load time. Actually, > > > > > > > > this adds a bit more stress than that since part of the EPC gets reserved > > > > > > > > for the Version Array (VA) pages. > > > > > > > > > > > > > > > > For each test, the page fault handler gets triggered in two occasions: > > > > > > > > > > > > > > > > - When SGX_IOC_ENCLAVE_INIT is performed, SECS gets swapped in by the > > > > > > > > page fault handler. > > > > > > > > - During the execution, each page that is referenced gets swapped in > > > > > > > > by the page fault handler. > > > > > > > > > > > > > > > > > > > > > > If I understand this correctly, all EPC pages are now being consumed during > > > > > > > fixture setup and thus every SGX test, no matter how big or small, now > > > > > > > becomes a stress test of the reclaimer instead of there being a unique > > > > > > > reclaimer test. Since an enclave is set up and torn down for every test this > > > > > > > seems like a significant addition. It also seems like this would impact > > > > > > > future tests of dynamic page addition where not all scenarios could be > > > > > > > tested with all EPC pages already consumed. > > > > > > > > > > > > > > Reinette > > > > > > > > > > > > Re-initializing the test enclave is mandatory thing to do for all tests > > > > > > because it has an internals state. > > > > > > > > > > > > > > > > Right, but not all tests require the same enclave. In kselftest terminology > > > > > I think you are attempting to force all tests to depend on the same test > > > > > fixture. Is it not possible to have a separate "reclaimer" test fixture that > > > > > would build an enclave with a large heap and then have reclaimer tests that > > > > > exercise it by being tests that are specific to this "reclaimer fixture"? > > > > > > > > > > Reinette > > > > > > > > Why add that complexity? > > > > > > > > > > With this change every test is turned into a pseudo reclaimer test without > > > there being any explicit testing (with pass/fail criteria) of reclaimer > > > behavior. This is an expensive addition and reduces the scenarios that the > > > tests can exercise. > > > > > > Reinette > > > > There is consistent known behaviour how reclaimer and also the page fault > > are exercised for each test. I think that is what matters most right now > > that the basic behaviour of both the page reclaimer and page fault handler > > gets exercised. > > I believe the basic behavior of page fault handler is currently exercised in > each test, this is required. This not true. The current test does not exercise ELDU code path. > > > > > I don't understand the real-world gain of doing something factors more > > complex than necessary at a particular point of time, when you don't > > really need to hang yourself into it forever. > > Your argument about "hang yourself into it forever" can go both ways - why > should all tests now unnecessarily consume the entire EPC forever? > > If I understand correctly adding a separate reclaimer test is not complex > but would require refactoring code. What does it matter anyway if code nees to be refactored? > > This patch does increase the coverage in a deterministic manner to the code > > paths that were not previously exercised, i.e. we know the code paths, and > > could even calculate the exact number of times that they are triggered. And > > without doing anything obscure. That's what matters to me. > > On the contrary this is indeed obfuscating the SGX tests: if an issue shows > up in the reclaimer then all tests would fail. If there is a unique > reclaimer test then that would help point to where the issue may be. I tend to disagree this. I'll add a separate reclaimer test if I need to test something that this does not scale. It's an iterative process. /Jarkko
