Repeat the checking of AMX component in xheader after XSAVEC when IA32_XFD[XTILEDATA] is set. This check calibrates the functionality scope of IA32_XFD: it does not intercept the XSAVE state management. Regardless of the values in IA32_XFD, AMX component state will still be managed by XSAVE* and XRSTOR* as long as the corresponding bits are set XCR0.
Signed-off-by: Mingwei Zhang mizhang@google.com --- tools/testing/selftests/kvm/x86_64/amx_test.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/tools/testing/selftests/kvm/x86_64/amx_test.c b/tools/testing/selftests/kvm/x86_64/amx_test.c index 62fff3363b3b..724e991ba814 100644 --- a/tools/testing/selftests/kvm/x86_64/amx_test.c +++ b/tools/testing/selftests/kvm/x86_64/amx_test.c @@ -201,6 +201,16 @@ static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg,
/* xfd=0x40000, disable amx tiledata */ wrmsr(MSR_IA32_XFD, XFEATURE_MASK_XTILEDATA); + + /* + * XTILEDATA is cleared in xstate_bv but set in xcomp_bv, this property + * remains the same even when amx tiledata is disabled by IA32_XFD. + */ + xstate->header.xstate_bv = XFEATURE_MASK_XTILEDATA; + __xsavec(xstate, XFEATURE_MASK_XTILEDATA); + GUEST_ASSERT(!(xstate->header.xstate_bv & XFEATURE_MASK_XTILEDATA)); + GUEST_ASSERT((xstate->header.xcomp_bv & XFEATURE_MASK_XTILEDATA)); + GUEST_SYNC(6); GUEST_ASSERT(rdmsr(MSR_IA32_XFD) == XFEATURE_MASK_XTILEDATA); set_tilecfg(amx_cfg);