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    SubjectRe: [PATCH v7 04/10] iommu/dma-reserved-iommu: alloc/free_reserved_iova_domain
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    On 19/04/16 17:56, Eric Auger wrote:
    > Introduce alloc/free_reserved_iova_domain in the IOMMU API.
    > alloc_reserved_iova_domain initializes an iova domain at a given
    > iova base address and with a given size. This iova domain will
    > be used to allocate iova within that window. Those IOVAs will be reserved
    > for special purpose, typically MSI frame binding. Allocation function
    > within the reserved iova domain will be introduced in subsequent patches.

    Am I the only one thinking "Yo dawg, I heard you like IOVA allocators,
    so we put an IOVA allocator in your IOVA allocator so you can allocate
    IOVAs while you allocate IOVAs."

    > Those functions are fully implemented if CONFIG_IOMMU_DMA_RESERVED
    > is set.

    DMA? I thought we were going to be dealing with MSI descriptors?

    > Signed-off-by: Eric Auger <eric.auger@linaro.org>
    >
    > ---
    > v7:
    > - fix locking
    > - add iova_cache_get/put
    > - static inline functions when CONFIG_IOMMU_DMA_RESERVED is not set
    > - introduce struct reserved_iova_domain to encapsulate prot info &
    > add prot parameter in alloc_reserved_iova_domain
    >
    > v5 -> v6:
    > - use spin lock instead of mutex
    >
    > v3 -> v4:
    > - formerly in "iommu/arm-smmu: implement alloc/free_reserved_iova_domain" &
    > "iommu: add alloc/free_reserved_iova_domain"
    >
    > v2 -> v3:
    > - remove iommu_alloc_reserved_iova_domain & iommu_free_reserved_iova_domain
    > static implementation in case CONFIG_IOMMU_API is not set
    >
    > v1 -> v2:
    > - moved from vfio API to IOMMU API
    > ---
    > drivers/iommu/Kconfig | 8 +++
    > drivers/iommu/Makefile | 1 +
    > drivers/iommu/dma-reserved-iommu.c | 99 ++++++++++++++++++++++++++++++++++++++
    > include/linux/dma-reserved-iommu.h | 59 +++++++++++++++++++++++
    > 4 files changed, 167 insertions(+)
    > create mode 100644 drivers/iommu/dma-reserved-iommu.c
    > create mode 100644 include/linux/dma-reserved-iommu.h
    >
    > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
    > index dd1dc39..a5a1530 100644
    > --- a/drivers/iommu/Kconfig
    > +++ b/drivers/iommu/Kconfig
    > @@ -74,6 +74,12 @@ config IOMMU_DMA
    > select IOMMU_IOVA
    > select NEED_SG_DMA_LENGTH
    >
    > +# IOMMU reserved IOVA mapping (MSI doorbell)

    The only reference to MSIs I can see, but I can't make head nor tail of
    it. Sorry, I don't understand this patch at all :(

    Robin.

    > +config IOMMU_DMA_RESERVED
    > + bool
    > + select IOMMU_API
    > + select IOMMU_IOVA
    > +
    > config FSL_PAMU
    > bool "Freescale IOMMU support"
    > depends on PPC32
    > @@ -307,6 +313,7 @@ config SPAPR_TCE_IOMMU
    > config ARM_SMMU
    > bool "ARM Ltd. System MMU (SMMU) Support"
    > depends on (ARM64 || ARM) && MMU
    > + select IOMMU_DMA_RESERVED
    > select IOMMU_API
    > select IOMMU_IO_PGTABLE_LPAE
    > select ARM_DMA_USE_IOMMU if ARM
    > @@ -320,6 +327,7 @@ config ARM_SMMU
    > config ARM_SMMU_V3
    > bool "ARM Ltd. System MMU Version 3 (SMMUv3) Support"
    > depends on ARM64 && PCI
    > + select IOMMU_DMA_RESERVED
    > select IOMMU_API
    > select IOMMU_IO_PGTABLE_LPAE
    > select GENERIC_MSI_IRQ_DOMAIN
    > diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
    > index c6edb31..6c9ae99 100644
    > --- a/drivers/iommu/Makefile
    > +++ b/drivers/iommu/Makefile
    > @@ -2,6 +2,7 @@ obj-$(CONFIG_IOMMU_API) += iommu.o
    > obj-$(CONFIG_IOMMU_API) += iommu-traces.o
    > obj-$(CONFIG_IOMMU_API) += iommu-sysfs.o
    > obj-$(CONFIG_IOMMU_DMA) += dma-iommu.o
    > +obj-$(CONFIG_IOMMU_DMA_RESERVED) += dma-reserved-iommu.o
    > obj-$(CONFIG_IOMMU_IO_PGTABLE) += io-pgtable.o
    > obj-$(CONFIG_IOMMU_IO_PGTABLE_ARMV7S) += io-pgtable-arm-v7s.o
    > obj-$(CONFIG_IOMMU_IO_PGTABLE_LPAE) += io-pgtable-arm.o
    > diff --git a/drivers/iommu/dma-reserved-iommu.c b/drivers/iommu/dma-reserved-iommu.c
    > new file mode 100644
    > index 0000000..2562af0
    > --- /dev/null
    > +++ b/drivers/iommu/dma-reserved-iommu.c
    > @@ -0,0 +1,99 @@
    > +/*
    > + * Reserved IOVA Management
    > + *
    > + * Copyright (c) 2015 Linaro Ltd.
    > + * www.linaro.org
    > + *
    > + * This program is free software; you can redistribute it and/or modify
    > + * it under the terms of the GNU General Public License version 2 as
    > + * published by the Free Software Foundation.
    > + *
    > + * This program is distributed in the hope that it will be useful,
    > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
    > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    > + * GNU General Public License for more details.
    > + *
    > + */
    > +
    > +#include <linux/iommu.h>
    > +#include <linux/iova.h>
    > +
    > +struct reserved_iova_domain {
    > + struct iova_domain *iovad;
    > + int prot; /* iommu protection attributes to be obeyed */
    > +};
    > +
    > +int iommu_alloc_reserved_iova_domain(struct iommu_domain *domain,
    > + dma_addr_t iova, size_t size, int prot,
    > + unsigned long order)
    > +{
    > + unsigned long granule, mask, flags;
    > + struct reserved_iova_domain *rid;
    > + int ret = 0;
    > +
    > + granule = 1UL << order;
    > + mask = granule - 1;
    > + if (iova & mask || (!size) || (size & mask))
    > + return -EINVAL;
    > +
    > + rid = kzalloc(sizeof(struct reserved_iova_domain), GFP_KERNEL);
    > + if (!rid)
    > + return -ENOMEM;
    > +
    > + rid->iovad = kzalloc(sizeof(struct iova_domain), GFP_KERNEL);
    > + if (!rid->iovad) {
    > + kfree(rid);
    > + return -ENOMEM;
    > + }
    > +
    > + iova_cache_get();
    > +
    > + init_iova_domain(rid->iovad, granule,
    > + iova >> order, (iova + size - 1) >> order);
    > +
    > + spin_lock_irqsave(&domain->reserved_lock, flags);
    > +
    > + if (domain->reserved_iova_cookie) {
    > + ret = -EEXIST;
    > + goto unlock;
    > + }
    > +
    > + domain->reserved_iova_cookie = rid;
    > +
    > +unlock:
    > + spin_unlock_irqrestore(&domain->reserved_lock, flags);
    > + if (ret) {
    > + put_iova_domain(rid->iovad);
    > + kfree(rid->iovad);
    > + kfree(rid);
    > + iova_cache_put();
    > + }
    > + return ret;
    > +}
    > +EXPORT_SYMBOL_GPL(iommu_alloc_reserved_iova_domain);
    > +
    > +void iommu_free_reserved_iova_domain(struct iommu_domain *domain)
    > +{
    > + struct reserved_iova_domain *rid;
    > + unsigned long flags;
    > + int ret = 0;
    > +
    > + spin_lock_irqsave(&domain->reserved_lock, flags);
    > +
    > + rid = (struct reserved_iova_domain *)domain->reserved_iova_cookie;
    > + if (!rid) {
    > + ret = -EINVAL;
    > + goto unlock;
    > + }
    > +
    > + domain->reserved_iova_cookie = NULL;
    > +unlock:
    > + spin_unlock_irqrestore(&domain->reserved_lock, flags);
    > + if (!ret) {
    > + put_iova_domain(rid->iovad);
    > + kfree(rid->iovad);
    > + kfree(rid);
    > + iova_cache_put();
    > + }
    > +}
    > +EXPORT_SYMBOL_GPL(iommu_free_reserved_iova_domain);
    > diff --git a/include/linux/dma-reserved-iommu.h b/include/linux/dma-reserved-iommu.h
    > new file mode 100644
    > index 0000000..01ec385
    > --- /dev/null
    > +++ b/include/linux/dma-reserved-iommu.h
    > @@ -0,0 +1,59 @@
    > +/*
    > + * Copyright (c) 2015 Linaro Ltd.
    > + * www.linaro.org
    > + *
    > + * This program is free software; you can redistribute it and/or modify
    > + * it under the terms of the GNU General Public License version 2 as
    > + * published by the Free Software Foundation.
    > + *
    > + * This program is distributed in the hope that it will be useful,
    > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
    > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    > + * GNU General Public License for more details.
    > + *
    > + */
    > +#ifndef __DMA_RESERVED_IOMMU_H
    > +#define __DMA_RESERVED_IOMMU_H
    > +
    > +#include <linux/types.h>
    > +#include <linux/kernel.h>
    > +
    > +struct iommu_domain;
    > +
    > +#ifdef CONFIG_IOMMU_DMA_RESERVED
    > +
    > +/**
    > + * iommu_alloc_reserved_iova_domain: allocate the reserved iova domain
    > + *
    > + * @domain: iommu domain handle
    > + * @iova: base iova address
    > + * @size: iova window size
    > + * @prot: protection attribute flags
    > + * @order: page order
    > + */
    > +int iommu_alloc_reserved_iova_domain(struct iommu_domain *domain,
    > + dma_addr_t iova, size_t size, int prot,
    > + unsigned long order);
    > +
    > +/**
    > + * iommu_free_reserved_iova_domain: free the reserved iova domain
    > + *
    > + * @domain: iommu domain handle
    > + */
    > +void iommu_free_reserved_iova_domain(struct iommu_domain *domain);
    > +
    > +#else
    > +
    > +static inline int
    > +iommu_alloc_reserved_iova_domain(struct iommu_domain *domain,
    > + dma_addr_t iova, size_t size, int prot,
    > + unsigned long order)
    > +{
    > + return -ENOENT;
    > +}
    > +
    > +static inline void
    > +iommu_free_reserved_iova_domain(struct iommu_domain *domain) {}
    > +
    > +#endif /* CONFIG_IOMMU_DMA_RESERVED */
    > +#endif /* __DMA_RESERVED_IOMMU_H */
    >

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