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From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: iommu@lists.linux-foundation.org,
	linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org
Cc: fenghua.yu@intel.com,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	catalin.marinas@arm.com, robin.murphy@arm.com, hch@infradead.org,
	zhengxiang9@huawei.com, zhangfei.gao@linaro.org, will@kernel.org
Subject: [PATCH v9 03/13] iommu/sva: Add PASID helpers
Date: Thu, 23 Jul 2020 16:57:15 +0200	[thread overview]
Message-ID: <20200723145724.3014766-4-jean-philippe@linaro.org> (raw)
In-Reply-To: <20200723145724.3014766-1-jean-philippe@linaro.org>

Let IOMMU drivers allocate a single PASID per mm. Store the mm in the
IOASID set to allow refcounting and searching mm by PASID, when handling
an I/O page fault.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 drivers/iommu/Kconfig         |  5 +++
 drivers/iommu/Makefile        |  1 +
 drivers/iommu/iommu-sva-lib.h | 15 +++++++
 drivers/iommu/iommu-sva-lib.c | 85 +++++++++++++++++++++++++++++++++++
 4 files changed, 106 insertions(+)
 create mode 100644 drivers/iommu/iommu-sva-lib.h
 create mode 100644 drivers/iommu/iommu-sva-lib.c

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 6dc49ed8377a..490c86e3615a 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -102,6 +102,11 @@ config IOMMU_DMA
 	select IRQ_MSI_IOMMU
 	select NEED_SG_DMA_LENGTH
 
+# Shared Virtual Addressing library
+config IOMMU_SVA_LIB
+	bool
+	select IOASID
+
 config FSL_PAMU
 	bool "Freescale IOMMU support"
 	depends on PCI
diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 342190196dfb..0fe5a7f9bc69 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -38,3 +38,4 @@ obj-$(CONFIG_S390_IOMMU) += s390-iommu.o
 obj-$(CONFIG_QCOM_IOMMU) += qcom_iommu.o
 obj-$(CONFIG_HYPERV_IOMMU) += hyperv-iommu.o
 obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o
+obj-$(CONFIG_IOMMU_SVA_LIB) += iommu-sva-lib.o
diff --git a/drivers/iommu/iommu-sva-lib.h b/drivers/iommu/iommu-sva-lib.h
new file mode 100644
index 000000000000..b40990aef3fd
--- /dev/null
+++ b/drivers/iommu/iommu-sva-lib.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * SVA library for IOMMU drivers
+ */
+#ifndef _IOMMU_SVA_LIB_H
+#define _IOMMU_SVA_LIB_H
+
+#include <linux/ioasid.h>
+#include <linux/mm_types.h>
+
+int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max);
+void iommu_sva_free_pasid(struct mm_struct *mm);
+struct mm_struct *iommu_sva_find(ioasid_t pasid);
+
+#endif /* _IOMMU_SVA_LIB_H */
diff --git a/drivers/iommu/iommu-sva-lib.c b/drivers/iommu/iommu-sva-lib.c
new file mode 100644
index 000000000000..db7e6c104d6b
--- /dev/null
+++ b/drivers/iommu/iommu-sva-lib.c
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Helpers for IOMMU drivers implementing SVA
+ */
+#include <linux/mutex.h>
+#include <linux/sched/mm.h>
+
+#include "iommu-sva-lib.h"
+
+static DEFINE_MUTEX(iommu_sva_lock);
+static DECLARE_IOASID_SET(iommu_sva_pasid);
+
+/**
+ * iommu_sva_alloc_pasid - Allocate a PASID for the mm
+ * @mm: the mm
+ * @min: minimum PASID value (inclusive)
+ * @max: maximum PASID value (inclusive)
+ *
+ * Try to allocate a PASID for this mm, or take a reference to the existing one
+ * provided it fits within the [min, max] range. On success the PASID is
+ * available in mm->pasid, and must be released with iommu_sva_free_pasid().
+ *
+ * Returns 0 on success and < 0 on error.
+ */
+int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max)
+{
+	int ret = 0;
+	ioasid_t pasid;
+
+	if (min == INVALID_IOASID || max == INVALID_IOASID ||
+	    min == 0 || max < min)
+		return -EINVAL;
+
+	mutex_lock(&iommu_sva_lock);
+	if (mm->pasid) {
+		if (mm->pasid >= min && mm->pasid <= max)
+			ioasid_get(mm->pasid);
+		else
+			ret = -EOVERFLOW;
+	} else {
+		pasid = ioasid_alloc(&iommu_sva_pasid, min, max, mm);
+		if (pasid == INVALID_IOASID)
+			ret = -ENOMEM;
+		else
+			mm->pasid = pasid;
+	}
+	mutex_unlock(&iommu_sva_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iommu_sva_alloc_pasid);
+
+/**
+ * iommu_sva_free_pasid - Release the mm's PASID
+ * @mm: the mm.
+ *
+ * Drop one reference to a PASID allocated with iommu_sva_alloc_pasid()
+ */
+void iommu_sva_free_pasid(struct mm_struct *mm)
+{
+	mutex_lock(&iommu_sva_lock);
+	if (ioasid_put(mm->pasid))
+		mm->pasid = 0;
+	mutex_unlock(&iommu_sva_lock);
+}
+EXPORT_SYMBOL_GPL(iommu_sva_free_pasid);
+
+/* ioasid wants a void * argument */
+static bool __mmget_not_zero(void *mm)
+{
+	return mmget_not_zero(mm);
+}
+
+/**
+ * iommu_sva_find() - Find mm associated to the given PASID
+ * @pasid: Process Address Space ID assigned to the mm
+ *
+ * On success a reference to the mm is taken, and must be released with mmput().
+ *
+ * Returns the mm corresponding to this PASID, or an error if not found.
+ */
+struct mm_struct *iommu_sva_find(ioasid_t pasid)
+{
+	return ioasid_find(&iommu_sva_pasid, pasid, __mmget_not_zero);
+}
+EXPORT_SYMBOL_GPL(iommu_sva_find);
-- 
2.27.0

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  parent reply	other threads:[~2020-07-23 15:05 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-23 14:57 [PATCH v9 00/13] iommu: Shared Virtual Addressing for SMMUv3 (PT sharing part) Jean-Philippe Brucker
2020-07-23 14:57 ` [PATCH v9 01/13] mm: Define pasid in mm Jean-Philippe Brucker
2020-07-23 14:57 ` [PATCH v9 02/13] iommu/ioasid: Add ioasid references Jean-Philippe Brucker
2020-07-23 14:57 ` Jean-Philippe Brucker [this message]
2020-07-23 14:57 ` [PATCH v9 04/13] arm64: mm: Pin down ASIDs for sharing mm with devices Jean-Philippe Brucker
2020-07-23 14:57 ` [PATCH v9 05/13] iommu/io-pgtable-arm: Move some definitions to a header Jean-Philippe Brucker
2020-07-23 14:57 ` [PATCH v9 06/13] arm64: cpufeature: Export symbol read_sanitised_ftr_reg() Jean-Philippe Brucker
2020-07-23 14:57 ` [PATCH v9 07/13] iommu/arm-smmu-v3: Move definitions to a header Jean-Philippe Brucker
2020-07-23 14:57 ` [PATCH v9 08/13] iommu/arm-smmu-v3: Share process page tables Jean-Philippe Brucker
2020-07-23 14:57 ` [PATCH v9 09/13] iommu/arm-smmu-v3: Seize private ASID Jean-Philippe Brucker
2020-07-23 14:57 ` [PATCH v9 10/13] iommu/arm-smmu-v3: Check for SVA features Jean-Philippe Brucker
2020-07-23 14:57 ` [PATCH v9 11/13] iommu/arm-smmu-v3: Add SVA device feature Jean-Philippe Brucker
2020-07-23 14:57 ` [PATCH v9 12/13] iommu/arm-smmu-v3: Implement iommu_sva_bind/unbind() Jean-Philippe Brucker
2020-07-23 14:57 ` [PATCH v9 13/13] iommu/arm-smmu-v3: Hook up ATC invalidation to mm ops Jean-Philippe Brucker

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