linux-kernel - [PATCH 5.19 1000/1157] selftests/powerpc: Fix matrix multiply assist test

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Message-Id: <20220815180519.784939569@linuxfoundation.org>
Date:   Mon, 15 Aug 2022 20:05:56 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Rashmica Gupta <rashmica@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.19 1000/1157] selftests/powerpc: Fix matrix multiply assist test

From: Rashmica Gupta <rashmica@...ux.ibm.com>

[ Upstream commit cd1e64935f79e31d666172c52c951ca97152b783 ]

The ISA states: "when ACC[i] contains defined data, the contents of VSRs
4×i to 4×i+3 are undefined until either a VSX Move From ACC instruction
is used to copy the contents of ACC[i] to VSRs 4×i to 4×i+3 or some other
instruction directly writes to one of these VSRs." We aren't doing this.

This test only works on Power10 because the hardware implementation
happens to map ACC0 to VSRs 0-3, but will fail on any other implementation
that doesn't do this. So add xxmfacc between writing to the accumulator
and accessing the VSRs.

Fixes: 3527e1ab9a79 ("selftests/powerpc: Add matrix multiply assist (MMA) test")
Signed-off-by: Rashmica Gupta <rashmica@...ux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Link: https://lore.kernel.org/r/20220617043935.428083-1-rashmica@linux.ibm.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 tools/testing/selftests/powerpc/math/mma.S | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/testing/selftests/powerpc/math/mma.S b/tools/testing/selftests/powerpc/math/mma.S
index 8528c9849565..61cc88b1b26b 100644
--- a/tools/testing/selftests/powerpc/math/mma.S
+++ b/tools/testing/selftests/powerpc/math/mma.S
@@ -20,6 +20,9 @@ test_mma:
 	/* xvi16ger2s */
 	.long	0xec042958
 
+	/* Deprime the accumulator - xxmfacc 0 */
+	.long 0x7c000162
+
 	/* Store result in image passed in r5 */
 	stxvw4x	0,0,5
 	addi	5,5,16
-- 
2.35.1