linux-kernel - [PATCH v3 6/6] iommu/dart: Remove force

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Message-Id: <20211019163737.46269-7-sven@svenpeter.dev>
Date:   Tue, 19 Oct 2021 18:37:37 +0200
From:   Sven Peter <sven@...npeter.dev>
To:     iommu@...ts.linux-foundation.org,
        Robin Murphy <robin.murphy@....com>
Cc:     Sven Peter <sven@...npeter.dev>, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>, Arnd Bergmann <arnd@...nel.org>,
        Marc Zyngier <maz@...nel.org>,
        Mohamed Mediouni <mohamed.mediouni@...amail.com>,
        Alexander Graf <graf@...zon.com>,
        Hector Martin <marcan@...can.st>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 6/6] iommu/dart: Remove force_bypass logic

Now that the dma-iommu API supports IOMMU granules which are larger than
the CPU page size and that the kernel no longer runs into a BUG_ON when
devices are attached to a domain with such a granule there's no need to
force bypass mode anymore.

Signed-off-by: Sven Peter <sven@...npeter.dev>
---
 drivers/iommu/apple-dart.c | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
index 280ff8df728d..ce92195db638 100644
--- a/drivers/iommu/apple-dart.c
+++ b/drivers/iommu/apple-dart.c
@@ -90,7 +90,6 @@
  * @lock: lock for hardware operations involving this dart
  * @pgsize: pagesize supported by this DART
  * @supports_bypass: indicates if this DART supports bypass mode
- * @force_bypass: force bypass mode due to pagesize mismatch?
  * @sid2group: maps stream ids to iommu_groups
  * @iommu: iommu core device
  */
@@ -107,7 +106,6 @@ struct apple_dart {
 
 	u32 pgsize;
 	u32 supports_bypass : 1;
-	u32 force_bypass : 1;
 
 	struct iommu_group *sid2group[DART_MAX_STREAMS];
 	struct iommu_device iommu;
@@ -488,9 +486,6 @@ static int apple_dart_attach_dev(struct iommu_domain *domain,
 	struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev);
 	struct apple_dart_domain *dart_domain = to_dart_domain(domain);
 
-	if (cfg->stream_maps[0].dart->force_bypass &&
-	    domain->type != IOMMU_DOMAIN_IDENTITY)
-		return -EINVAL;
 	if (!cfg->stream_maps[0].dart->supports_bypass &&
 	    domain->type == IOMMU_DOMAIN_IDENTITY)
 		return -EINVAL;
@@ -619,8 +614,6 @@ static int apple_dart_of_xlate(struct device *dev, struct of_phandle_args *args)
 	if (cfg_dart) {
 		if (cfg_dart->supports_bypass != dart->supports_bypass)
 			return -EINVAL;
-		if (cfg_dart->force_bypass != dart->force_bypass)
-			return -EINVAL;
 		if (cfg_dart->pgsize != dart->pgsize)
 			return -EINVAL;
 	}
@@ -726,8 +719,6 @@ static int apple_dart_def_domain_type(struct device *dev)
 {
 	struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev);
 
-	if (cfg->stream_maps[0].dart->force_bypass)
-		return IOMMU_DOMAIN_IDENTITY;
 	if (!cfg->stream_maps[0].dart->supports_bypass)
 		return IOMMU_DOMAIN_DMA;
 
@@ -884,7 +875,6 @@ static int apple_dart_probe(struct platform_device *pdev)
 	dart_params[1] = readl(dart->regs + DART_PARAMS2);
 	dart->pgsize = 1 << FIELD_GET(DART_PARAMS_PAGE_SHIFT, dart_params[0]);
 	dart->supports_bypass = dart_params[1] & DART_PARAMS_BYPASS_SUPPORT;
-	dart->force_bypass = dart->pgsize > PAGE_SIZE;
 
 	ret = request_irq(dart->irq, apple_dart_irq, IRQF_SHARED,
 			  "apple-dart fault handler", dart);
@@ -908,8 +898,8 @@ static int apple_dart_probe(struct platform_device *pdev)
 
 	dev_info(
 		&pdev->dev,
-		"DART [pagesize %x, bypass support: %d, bypass forced: %d] initialized\n",
-		dart->pgsize, dart->supports_bypass, dart->force_bypass);
+		"DART [pagesize %x, bypass support: %d] initialized\n",
+		dart->pgsize, dart->supports_bypass);
 	return 0;
 
 err_sysfs_remove:
-- 
2.25.1