Reply-To: Mingwei Zhang <mizhang@google.com>
Date:   Tue, 21 Feb 2023 16:36:50 +0000
In-Reply-To: <20230221163655.920289-1-mizhang@google.com>
Mime-Version: 1.0
References: <20230221163655.920289-1-mizhang@google.com>
Message-ID: <20230221163655.920289-9-mizhang@google.com>
Subject: [PATCH v3 08/13] KVM: selftests: x86: Repeat the checking of xheader
 when IA32_XFD[XTILEDATA] is set in 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

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);
-- 
2.39.2.637.g21b0678d19-goog