Reply-To: Mingwei Zhang <mizhang@google.com>
Date:   Tue, 21 Feb 2023 16:36:45 +0000
In-Reply-To: <20230221163655.920289-1-mizhang@google.com>
Mime-Version: 1.0
References: <20230221163655.920289-1-mizhang@google.com>
Message-ID: <20230221163655.920289-4-mizhang@google.com>
Subject: [PATCH v3 03/13] KVM: selftests: x86: Fix an error in comment of amx_test
From:   Mingwei Zhang <mizhang@google.com>
To:     Sean Christopherson <seanjc@google.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>
Cc:     "H. Peter Anvin" <hpa@zytor.com>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, linux-kselftest@vger.kernel.org,
        Mingwei Zhang <mizhang@google.com>,
        Jim Mattson <jmattson@google.com>,
        Venkatesh Srinivas <venkateshs@google.com>,
        Aaron Lewis <aaronlewis@google.com>,
        "Chang S. Bae" <chang.seok.bae@intel.com>,
        Chao Gao <chao.gao@intel.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

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>
---
 tools/testing/selftests/kvm/x86_64/amx_test.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/x86_64/amx_test.c b/tools/testing/selftests/kvm/x86_64/amx_test.c
index bb9dc0008f43..16c857c1052e 100644
--- 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));
-- 
2.39.2.637.g21b0678d19-goog