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Subject[PATCH v3 04/13] KVM: selftests: x86: Enable checking on xcomp_bv in amx_test
After tilerelease instruction, AMX tiles are in INIT state. According to
Intel SDM vol 1. 13.10: "If RFBM[i] = 1, XSTATE_BV[i] is set to the
value of XINUSE[i].", XSTATE_BV[18] should be cleared after xsavec.

On the other hand, according to Intel SDM vol 1. 13.4.3: "If XCOMP_BV[i] =
1, state component i is located at a byte offset locationI from the base
address of the XSAVE area". Since at the time of xsavec, XCR0[18] is set
indicating AMX tile data component is still enabled, xcomp_bv[18] should be

Complete the checks by adding the assert to xcomp_bv[18] after xsavec.

Signed-off-by: Mingwei Zhang <>
tools/testing/selftests/kvm/x86_64/amx_test.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/kvm/x86_64/amx_test.c b/tools/testing/selftests/kvm/x86_64/amx_test.c
index 16c857c1052e..ba8c0afdbac8 100644
--- a/tools/testing/selftests/kvm/x86_64/amx_test.c
+++ b/tools/testing/selftests/kvm/x86_64/amx_test.c
@@ -197,6 +197,7 @@ static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg,
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));

/* xfd=0x40000, disable amx tiledata */
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