Re: [PATCH 5/7] iommu/dma: add support for non-strict mode
From: Leizhen (ThunderTown)
Date: Mon Jun 04 2018 - 08:05:39 EST
On 2018/5/31 21:04, Robin Murphy wrote:
> 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.
That's right. Pass domain to the static function iommu_dma_free_iova will be better.
>
>> Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
>> ---
>> 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...
OK
>
>> +{
>> + 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.
>
>> };
>> /*
>>
>
> .
>
--
Thanks!
BestRegards