On 5/25/21 3:22 PM, Dave Kleikamp wrote: > On 5/25/21 5:18 PM, Dave Hansen wrote: >> What values do PKRU and the shadow have when the test fails? Is PKRU 0? >> Any idea how xfeatures&0x200 got clear? > > I did observe that PKRU is 0 right before the failure. > > Shouldn't this still be a valid value? It's architecturall *valid* in the hardware for sure, but nothing in the tests or the kernel should ever set PKRU=0. The selftest is noticing that it ends up at a value that's entirely unexpected and properly bugging out. The reason I'm suspecting an XRSTOR is that the kernel always calls XRSTOR(RFBM=-1) setting all of the bits in the Requested Feature BitMap (RFBM). If RFBM[X]=1 and XSTATE_BV[i]=0 (XSTATE_BV is 'xfeatures' in the traces), then the state component is set to its initial configuration, which for PKRU is 0. That's why I'm asking how xfeatures&0x200 got clear.
