KVM: selftests: Fix an error in comment of amx_test

After the execution of __tilerelease(), AMX component will be in INIT
state. Therefore, execution of XSAVEC saving the AMX state into memory will
cause the xstate_bv[18] cleared in xheader. However, the xcomp_bv[18] will
remain set. Fix the error in comment. Also, update xsavec() to XSAVEC
because xcomp_bv[18] is set due to the instruction, not the function.
Finally, use XTILEDATA instead 'bit 18' in comments.

Cc: Jim Mattson <jmattson@google.com>
Cc: Venkatesh Srinivas <venkateshs@google.com>
Cc: Aaron Lewis <aaronlewis@google.com>
Signed-off-by: Mingwei Zhang <mizhang@google.com>
Link: https://lore.kernel.org/r/20230221163655.920289-4-mizhang@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/tools/testing/selftests/kvm/x86_64/amx_test.c b/tools/testing/selftests/kvm/x86_64/amx_test.c
index 59e0a573652d9b504d2d253d262068f20223f708..c59d7ff0b01d8d9750727935fe03776aff82fd84 100644 (file)
--- a/tools/testing/selftests/kvm/x86_64/amx_test.c
+++ b/tools/testing/selftests/kvm/x86_64/amx_test.c
@@ -190,7 +190,10 @@ static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg,
        GUEST_SYNC(4);
        __tilerelease();
        GUEST_SYNC(5);
-       /* bit 18 not in the XCOMP_BV after xsavec() */
+       /*
+        * After XSAVEC, XTILEDATA is cleared in the xstate_bv but is set in
+        * the xcomp_bv.
+        */
        xstate->header.xstate_bv = XFEATURE_MASK_XTILEDATA;
        __xsavec(xstate, XFEATURE_MASK_XTILEDATA);
        GUEST_ASSERT(!(xstate->header.xstate_bv & XFEATURE_MASK_XTILEDATA));