[PATCH v7 04/10] iommu/dma-reserved-iommu: alloc/free_reserved_iova_domain
Eric Auger
eric.auger at linaro.org
Wed Apr 20 06:11:04 PDT 2016
On 04/20/2016 03:03 PM, Robin Murphy wrote:
> 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."
I will try to rephrase ;-)
>
>> Those functions are fully implemented if CONFIG_IOMMU_DMA_RESERVED
>> is set.
>
> DMA? I thought we were going to be dealing with MSI descriptors?
Initially this was aiming at mapping MSI frames but some people
requested it becomes a generic API to allocate so called "reserved IOVA"
usable to map special physical pages, such as MSI frames.
Hope it clarifies a little bit :-(
Eric
>
>> Signed-off-by: Eric Auger <eric.auger at 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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