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From: Rashmica Gupta <rashmica@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: npiggin@gmail.com, alistair@popple.id.au
Subject: [PATCH] selftests/powerpc: Fix matrix multiply assist test
Date: Fri, 17 Jun 2022 14:39:35 +1000	[thread overview]
Message-ID: <20220617043935.428083-1-rashmica@linux.ibm.com> (raw)

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 commit 3527e1ab9a79 ("selftests/powerpc: Add matrix multiply assist
(MMA) test")

Signed-off-by: Rashmica Gupta <rashmica@linux.ibm.com>
---
 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
-- 
2.35.3


             reply	other threads:[~2022-06-17  4:40 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-17  4:39 Rashmica Gupta [this message]
2022-07-29 13:03 ` [PATCH] selftests/powerpc: Fix matrix multiply assist test Michael Ellerman

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