linux-kernel - [PATCH v6 16/21] iommu/tegra: gart: Allow only one active domain at a time

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Message-Id: <20181209202950.31486-17-digetx@gmail.com>
Date:   Sun,  9 Dec 2018 23:29:45 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Joerg Roedel <joro@...tes.org>
Cc:     Robin Murphy <robin.murphy@....com>,
        iommu@...ts.linux-foundation.org, devicetree@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v6 16/21] iommu/tegra: gart: Allow only one active domain at a time

GART has a single address space that is shared by all devices, hence only
one domain could be active at a time.

Signed-off-by: Dmitry Osipenko <digetx@...il.com>
Acked-by: Thierry Reding <treding@...dia.com>
---
 drivers/iommu/tegra-gart.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/iommu/tegra-gart.c b/drivers/iommu/tegra-gart.c
index bb5303b06845..1be595d15e7e 100644
--- a/drivers/iommu/tegra-gart.c
+++ b/drivers/iommu/tegra-gart.c
@@ -57,6 +57,7 @@ struct gart_device {
 	spinlock_t		pte_lock;	/* for pagetable */
 	struct list_head	client;
 	spinlock_t		client_lock;	/* for client list */
+	struct iommu_domain	*active_domain;	/* current active domain */
 	struct device		*dev;
 
 	struct iommu_device	iommu;		/* IOMMU Core handle */
@@ -186,6 +187,12 @@ static int gart_iommu_attach_dev(struct iommu_domain *domain,
 			goto fail;
 		}
 	}
+	if (gart->active_domain && gart->active_domain != domain) {
+		dev_err(gart->dev, "Only one domain can be active at a time\n");
+		err = -EINVAL;
+		goto fail;
+	}
+	gart->active_domain = domain;
 	list_add(&client->list, &gart->client);
 	spin_unlock(&gart->client_lock);
 	dev_dbg(gart->dev, "Attached %s\n", dev_name(dev));
@@ -208,6 +215,8 @@ static void __gart_iommu_detach_dev(struct iommu_domain *domain,
 		if (c->dev == dev) {
 			list_del(&c->list);
 			devm_kfree(gart->dev, c);
+			if (list_empty(&gart->client))
+				gart->active_domain = NULL;
 			dev_dbg(gart->dev, "Detached %s\n", dev_name(dev));
 			return;
 		}
-- 
2.19.1