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SubjectRe: [PATCH v3 2/6] iommu/dma: add support for non-strict mode
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On 2018-07-12 7:18 AM, 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. Add a new iommu capability: 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. If the domain is non-strict, call queue_iova to
> put off iova freeing.
>
> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
> ---
> drivers/iommu/dma-iommu.c | 25 +++++++++++++++++++++++++
> include/linux/iommu.h | 7 +++++++
> 2 files changed, 32 insertions(+)
>
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index ddcbbdb..9f0c77a 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_non_strict;
> };
>
> static inline size_t cookie_msi_granule(struct iommu_dma_cookie *cookie)
> @@ -257,6 +258,17 @@ static int iova_reserve_iommu_regions(struct device *dev,
> return ret;
> }
>
> +static void iommu_dma_flush_iotlb_all(struct iova_domain *iovad)
> +{
> + struct iommu_dma_cookie *cookie;
> + struct iommu_domain *domain;
> +
> + cookie = container_of(iovad, struct iommu_dma_cookie, iovad);
> + domain = cookie->domain_non_strict;
> +
> + 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()
> @@ -272,6 +284,7 @@ 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;
> @@ -308,6 +321,15 @@ 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)) &&
> + (IOMMU_DOMAIN_STRICT_MODE(domain) == IOMMU_NON_STRICT)) {
> + BUG_ON(!ops->flush_iotlb_all);
> +
> + cookie->domain_non_strict = domain;
> + init_iova_flush_queue(iovad, iommu_dma_flush_iotlb_all, NULL);
> + }
> +
> if (!dev)
> return 0;
>
> @@ -390,6 +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 (cookie->domain_non_strict)
> + 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 19938ee..82ed979 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -86,6 +86,12 @@ struct iommu_domain_geometry {
> #define IOMMU_DOMAIN_DMA (__IOMMU_DOMAIN_PAGING | \
> __IOMMU_DOMAIN_DMA_API)
>
> +#define IOMMU_STRICT 0
> +#define IOMMU_NON_STRICT 1
> +#define IOMMU_STRICT_MODE_MASK 1UL
> +#define IOMMU_DOMAIN_STRICT_MODE(domain) \
> + (domain->type != IOMMU_DOMAIN_UNMANAGED)
> +
> struct iommu_domain {
> unsigned type;
> const struct iommu_ops *ops;
> @@ -101,6 +107,7 @@ 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 still isn't a capability of the hardware. Non-strict mode is pure
software policy; *every IOMMU ever* supports it.

If you want to have this kind of per-driver control, make it a domain
attribute - that's not only more logical, but should also work out a lot
cleaner overall.

Robin.

> };
>
> /*
>

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