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Date: Thu, 31 May 2018 14:04:47 +0100
From: Robin Murphy <robin.murphy@....com>
To: Zhen Lei <thunder.leizhen@...wei.com>,
Will Deacon <will.deacon@....com>,
Matthias Brugger <matthias.bgg@...il.com>,
Rob Clark <robdclark@...il.com>,
Joerg Roedel <joro@...tes.org>,
linux-mediatek <linux-mediatek@...ts.infradead.org>,
linux-arm-msm <linux-arm-msm@...r.kernel.org>,
linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
iommu <iommu@...ts.linux-foundation.org>,
linux-kernel <linux-kernel@...r.kernel.org>
Cc: Hanjun Guo <guohanjun@...wei.com>, Libin <huawei.libin@...wei.com>,
Guozhu Li <liguozhu@...ilicon.com>,
Xinwei Hu <huxinwei@...wei.com>
Subject: Re: [PATCH 5/7] iommu/dma: add support for non-strict mode
On 31/05/18 08:42, Zhen Lei wrote:
> 1. Save the related domain pointer in struct iommu_dma_cookie, make iovad
> capable call domain->ops->flush_iotlb_all to flush TLB.
> 2. Define a new iommu capable: IOMMU_CAP_NON_STRICT, which used to indicate
> that the iommu domain support non-strict mode.
> 3. During the iommu domain initialization phase, call capable() to check
> whether it support non-strcit mode. If so, call init_iova_flush_queue
> to register iovad->flush_cb callback.
> 4. All unmap(contains iova-free) APIs will finally invoke __iommu_dma_unmap
> -->iommu_dma_free_iova. Use iovad->flush_cb to check whether its related
> iommu support non-strict mode or not, and call IOMMU_DOMAIN_IS_STRICT to
> make sure the IOMMU_DOMAIN_UNMANAGED domain always follow strict mode.
Once again, this is a whole load of complexity for a property which
could just be statically encoded at allocation, e.g. in the cookie type.
> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
> ---
> drivers/iommu/dma-iommu.c | 29 ++++++++++++++++++++++++++---
> include/linux/iommu.h | 3 +++
> 2 files changed, 29 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index 4e885f7..2e116d9 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -55,6 +55,7 @@ struct iommu_dma_cookie {
> };
> struct list_head msi_page_list;
> spinlock_t msi_lock;
> + struct iommu_domain *domain;
> };
>
> static inline size_t cookie_msi_granule(struct iommu_dma_cookie *cookie)
> @@ -64,7 +65,8 @@ static inline size_t cookie_msi_granule(struct iommu_dma_cookie *cookie)
> return PAGE_SIZE;
> }
>
> -static struct iommu_dma_cookie *cookie_alloc(enum iommu_dma_cookie_type type)
> +static struct iommu_dma_cookie *cookie_alloc(struct iommu_domain *domain,
> + enum iommu_dma_cookie_type type)
> {
> struct iommu_dma_cookie *cookie;
>
> @@ -73,6 +75,7 @@ static struct iommu_dma_cookie *cookie_alloc(enum iommu_dma_cookie_type type)
> spin_lock_init(&cookie->msi_lock);
> INIT_LIST_HEAD(&cookie->msi_page_list);
> cookie->type = type;
> + cookie->domain = domain;
> }
> return cookie;
> }
> @@ -94,7 +97,7 @@ int iommu_get_dma_cookie(struct iommu_domain *domain)
> if (domain->iova_cookie)
> return -EEXIST;
>
> - domain->iova_cookie = cookie_alloc(IOMMU_DMA_IOVA_COOKIE);
> + domain->iova_cookie = cookie_alloc(domain, IOMMU_DMA_IOVA_COOKIE);
> if (!domain->iova_cookie)
> return -ENOMEM;
>
> @@ -124,7 +127,7 @@ int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base)
> if (domain->iova_cookie)
> return -EEXIST;
>
> - cookie = cookie_alloc(IOMMU_DMA_MSI_COOKIE);
> + cookie = cookie_alloc(domain, IOMMU_DMA_MSI_COOKIE);
> if (!cookie)
> return -ENOMEM;
>
> @@ -261,6 +264,17 @@ static int iova_reserve_iommu_regions(struct device *dev,
> return ret;
> }
>
> +static void iova_flush_iotlb_all(struct iova_domain *iovad)
iommu_dma_flush...
> +{
> + struct iommu_dma_cookie *cookie;
> + struct iommu_domain *domain;
> +
> + cookie = container_of(iovad, struct iommu_dma_cookie, iovad);
> + domain = cookie->domain;
> +
> + domain->ops->flush_iotlb_all(domain);
> +}
> +
> /**
> * iommu_dma_init_domain - Initialise a DMA mapping domain
> * @domain: IOMMU domain previously prepared by iommu_get_dma_cookie()
> @@ -276,6 +290,7 @@ static int iova_reserve_iommu_regions(struct device *dev,
> int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,
> u64 size, struct device *dev)
> {
> + const struct iommu_ops *ops = domain->ops;
> struct iommu_dma_cookie *cookie = domain->iova_cookie;
> struct iova_domain *iovad = &cookie->iovad;
> unsigned long order, base_pfn, end_pfn;
> @@ -313,6 +328,11 @@ int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,
>
> init_iova_domain(iovad, 1UL << order, base_pfn);
>
> + if (ops->capable && ops->capable(IOMMU_CAP_NON_STRICT)) {
> + BUG_ON(!ops->flush_iotlb_all);
> + init_iova_flush_queue(iovad, iova_flush_iotlb_all, NULL);
> + }
> +
> return iova_reserve_iommu_regions(dev, domain);
> }
> EXPORT_SYMBOL(iommu_dma_init_domain);
> @@ -392,6 +412,9 @@ static void iommu_dma_free_iova(struct iommu_dma_cookie *cookie,
> /* The MSI case is only ever cleaning up its most recent allocation */
> if (cookie->type == IOMMU_DMA_MSI_COOKIE)
> cookie->msi_iova -= size;
> + else if (!IOMMU_DOMAIN_IS_STRICT(cookie->domain) && iovad->flush_cb)
> + queue_iova(iovad, iova_pfn(iovad, iova),
> + size >> iova_shift(iovad), 0);
> else
> free_iova_fast(iovad, iova_pfn(iovad, iova),
> size >> iova_shift(iovad));
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 39b3150..01ff569 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -87,6 +87,8 @@ struct iommu_domain_geometry {
> __IOMMU_DOMAIN_DMA_API)
>
> #define IOMMU_STRICT 1
> +#define IOMMU_DOMAIN_IS_STRICT(domain) \
> + (domain->type == IOMMU_DOMAIN_UNMANAGED)
>
> struct iommu_domain {
> unsigned type;
> @@ -103,6 +105,7 @@ enum iommu_cap {
> transactions */
> IOMMU_CAP_INTR_REMAP, /* IOMMU supports interrupt isolation */
> IOMMU_CAP_NOEXEC, /* IOMMU_NOEXEC flag */
> + IOMMU_CAP_NON_STRICT, /* IOMMU supports non-strict mode */
This isn't a property of the IOMMU, it depends purely on the driver
implementation. I think it also doesn't matter anyway - if a caller asks
for lazy unmapping on their domain but the IOMMU driver just does strict
unmaps anyway because that's all it supports, there's no actual harm done.
Robin.
> };
>
> /*
>
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