From cfc78dfd9b36dcda7c3ca9cdfca343f84c72252f Mon Sep 17 00:00:00 2001 From: Jean-Philippe Brucker Date: Fri, 6 Nov 2020 16:50:48 +0100 Subject: iommu/sva: Add PASID helpers 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. Signed-off-by: Jean-Philippe Brucker Reviewed-by: Lu Baolu Link: https://lore.kernel.org/r/20201106155048.997886-3-jean-philippe@linaro.org Signed-off-by: Will Deacon --- drivers/iommu/Kconfig | 5 +++ drivers/iommu/Makefile | 1 + drivers/iommu/iommu-sva-lib.c | 86 +++++++++++++++++++++++++++++++++++++++++++ drivers/iommu/iommu-sva-lib.h | 15 ++++++++ 4 files changed, 107 insertions(+) create mode 100644 drivers/iommu/iommu-sva-lib.c create mode 100644 drivers/iommu/iommu-sva-lib.h diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig index 04878caf6da4..f5ebbdfbf636 100644 --- a/drivers/iommu/Kconfig +++ b/drivers/iommu/Kconfig @@ -103,6 +103,11 @@ 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 11f1771104f3..61bd30cd8369 100644 --- a/drivers/iommu/Makefile +++ b/drivers/iommu/Makefile @@ -27,3 +27,4 @@ obj-$(CONFIG_FSL_PAMU) += fsl_pamu.o fsl_pamu_domain.o obj-$(CONFIG_S390_IOMMU) += s390-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.c b/drivers/iommu/iommu-sva-lib.c new file mode 100644 index 000000000000..bd41405d34e9 --- /dev/null +++ b/drivers/iommu/iommu-sva-lib.c @@ -0,0 +1,86 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Helpers for IOMMU drivers implementing SVA + */ +#include +#include + +#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(). + * @min must be greater than 0, because 0 indicates an unused mm->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_find getter() requires 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); 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 +#include + +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 */ -- cgit v1.2.3