linux-kernel - [PATCH] iommu/io-pgtable-dart: Only set subpage protection disable for DART 1

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Message-Id: <20250219-dart2-no-sp-disable-v1-1-9f324cfa4e70@gmail.com>
Date: Wed, 19 Feb 2025 10:13:53 +0100
From: Sasha Finkelstein via B4 Relay <devnull+fnkl.kernel.gmail.com@...nel.org>
To: Sven Peter <sven@...npeter.dev>, 
 Alyssa Rosenzweig <alyssa@...enzweig.io>, Joerg Roedel <joro@...tes.org>, 
 Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>, 
 Hector Martin <marcan@...can.st>, Rob Herring <robh@...nel.org>, 
 Janne Grunau <j@...nau.net>
Cc: Joerg Roedel <jroedel@...e.de>, asahi@...ts.linux.dev, 
 linux-arm-kernel@...ts.infradead.org, iommu@...ts.linux.dev, 
 linux-kernel@...r.kernel.org, Asahi Lina <lina@...hilina.net>, 
 Sasha Finkelstein <fnkl.kernel@...il.com>
Subject: [PATCH] iommu/io-pgtable-dart: Only set subpage protection disable
 for DART 1

From: Asahi Lina <lina@...hilina.net>

Subpage protection can't be disabled on t6000-style darts,
as such the disable flag no longer applies, and probably
even affects something else.

Fixes: dc09fe1c5edd ("iommu/io-pgtable-dart: Add DART PTE support for t6000")
Signed-off-by: Asahi Lina <lina@...hilina.net>
Signed-off-by: Sasha Finkelstein <fnkl.kernel@...il.com>
---
 drivers/iommu/io-pgtable-dart.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/io-pgtable-dart.c b/drivers/iommu/io-pgtable-dart.c
index c004640640ee50d01dd54c38e89162c0fcb1988f..06aca9ab52f9a811a2608ae75155a36919799c74 100644
--- a/drivers/iommu/io-pgtable-dart.c
+++ b/drivers/iommu/io-pgtable-dart.c
@@ -135,7 +135,6 @@ static int dart_init_pte(struct dart_io_pgtable *data,
 	pte |= FIELD_PREP(APPLE_DART_PTE_SUBPAGE_START, 0);
 	pte |= FIELD_PREP(APPLE_DART_PTE_SUBPAGE_END, 0xfff);
 
-	pte |= APPLE_DART1_PTE_PROT_SP_DIS;
 	pte |= APPLE_DART_PTE_VALID;
 
 	for (i = 0; i < num_entries; i++)
@@ -211,6 +210,7 @@ static dart_iopte dart_prot_to_pte(struct dart_io_pgtable *data,
 	dart_iopte pte = 0;
 
 	if (data->iop.fmt == APPLE_DART) {
+		pte |= APPLE_DART1_PTE_PROT_SP_DIS;
 		if (!(prot & IOMMU_WRITE))
 			pte |= APPLE_DART1_PTE_PROT_NO_WRITE;
 		if (!(prot & IOMMU_READ))

---
base-commit: 2408a807bfc3f738850ef5ad5e3fd59d66168996
change-id: 20250219-dart2-no-sp-disable-f35072cbbd96