KVM: selftests: Assert that both XTILE{CFG,DATA} are XSAVE-enabled

Assert that both XTILE{CFG,DATA} are written and read back via XSETBV and
XGETBV respectively.  The original check in amx_test only ensures at least
one of the XTILE bits are set, XTILECFG or XTILEDATA, when it really
should be checking that both are set.

Fixes: bf70636 ("selftest: kvm: Add amx selftest")
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Signed-off-by: Mingwei Zhang <mizhang@google.com>
Link: https://lore.kernel.org/r/20230221163655.920289-11-mizhang@google.com
[sean: massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: suomilewis

tools/testing/selftests/kvm/x86_64/amx_test.c

@@ -161,7 +161,7 @@ static void init_regs(void)
 	xcr0 = __xgetbv(0);
 	xcr0 |= XFEATURE_MASK_XTILE;
 	__xsetbv(0x0, xcr0);
-	GUEST_ASSERT(__xgetbv(0) & XFEATURE_MASK_XTILE);
+	GUEST_ASSERT((__xgetbv(0) & XFEATURE_MASK_XTILE) == XFEATURE_MASK_XTILE);
 }
 
 static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg,