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From:   Hector Martin <marcan@marcan.st>
Date:   Fri, 22 Sep 2023 23:55:23 +0900
Subject: [PATCH REGRESSION v2] iommu/apple-dart: Handle DMA_FQ domains in
 attach_dev()
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Message-Id: <20230922-iommu-type-regression-v2-1-689b2ba9b673@marcan.st>
To:     Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Jerry Snitselaar <jsnitsel@redhat.com>
Cc:     Joerg Roedel <jroedel@suse.de>, Neal Gompa <neal@gompa.dev>,
        "Justin M. Forbes" <jforbes@fedoraproject.org>,
        iommu@lists.linux.dev, linux-kernel@vger.kernel.org,
        asahi@lists.linux.dev, stable@vger.kernel.org,
        regressions@lists.linux.dev, Hector Martin <marcan@marcan.st>
Precedence: bulk

Commit a4fdd9762272 ("iommu: Use flush queue capability") hid the
IOMMU_DOMAIN_DMA_FQ domain type from domain allocation. A check was
introduced in iommu_dma_init_domain() to fall back if not supported, but
this check runs too late: by that point, devices have been attached to
the IOMMU, and apple-dart's attach_dev() callback does not expect
IOMMU_DOMAIN_DMA_FQ domains.

Change the logic so the IOMMU_DOMAIN_DMA codepath is the default,
instead of explicitly enumerating all types.

Fixes an apple-dart regression in v6.5.

Cc: regressions@lists.linux.dev
Cc: stable@vger.kernel.org
Suggested-by: Robin Murphy <robin.murphy@arm.com>
Fixes: a4fdd9762272 ("iommu: Use flush queue capability")
Signed-off-by: Hector Martin <marcan@marcan.st>
---
Changes in v2:
- Fixed the issue in apple-dart instead of the iommu core, per Robin's
  suggestion.
- Link to v1: https://lore.kernel.org/r/20230922-iommu-type-regression-v1-1-1ed3825b2c38@marcan.st
---
 drivers/iommu/apple-dart.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
index 2082081402d3..0b8927508427 100644
--- a/drivers/iommu/apple-dart.c
+++ b/drivers/iommu/apple-dart.c
@@ -671,8 +671,7 @@ static int apple_dart_attach_dev(struct iommu_domain *domain,
 		return ret;
 
 	switch (domain->type) {
-	case IOMMU_DOMAIN_DMA:
-	case IOMMU_DOMAIN_UNMANAGED:
+	default:
 		ret = apple_dart_domain_add_streams(dart_domain, cfg);
 		if (ret)
 			return ret;

---
base-commit: ce9ecca0238b140b88f43859b211c9fdfd8e5b70
change-id: 20230922-iommu-type-regression-25b4f43df770

Best regards,
-- 
Hector Martin <marcan@marcan.st>