From: Damien Le Moal via iommu <iommu@lists.linux-foundation.org>
To: John Garry <john.garry@huawei.com>,
joro@8bytes.org, will@kernel.org, jejb@linux.ibm.com,
martin.petersen@oracle.com, hch@lst.de, m.szyprowski@samsung.com,
robin.murphy@arm.com
Cc: linux-scsi@vger.kernel.org, linux-doc@vger.kernel.org,
liyihang6@hisilicon.com, linux-kernel@vger.kernel.org,
linux-ide@vger.kernel.org, iommu@lists.linux-foundation.org
Subject: Re: [PATCH v2 2/4] dma-iommu: Add iommu_dma_opt_mapping_size()
Date: Fri, 27 May 2022 07:56:50 +0900 [thread overview]
Message-ID: <36dbfa77-d8f0-88d4-7dda-1e18c4c453b8@opensource.wdc.com> (raw)
In-Reply-To: <1653560914-82185-3-git-send-email-john.garry@huawei.com>
On 2022/05/26 19:28, John Garry wrote:
> Add the IOMMU callback for DMA mapping API dma_opt_mapping_size(), which
> allows the drivers to know the optimal mapping limit and thus limit the
> requested IOVA lengths.
>
> This value is based on the IOVA rcache range limit, as IOVAs allocated
> above this limit must always be newly allocated, which may be quite slow.
>
> Signed-off-by: John Garry <john.garry@huawei.com>
> ---
> drivers/iommu/dma-iommu.c | 6 ++++++
> drivers/iommu/iova.c | 5 +++++
> include/linux/iova.h | 2 ++
> 3 files changed, 13 insertions(+)
>
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index 09f6e1c0f9c0..f619e41b9172 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -1442,6 +1442,11 @@ static unsigned long iommu_dma_get_merge_boundary(struct device *dev)
> return (1UL << __ffs(domain->pgsize_bitmap)) - 1;
> }
>
> +static size_t iommu_dma_opt_mapping_size(void)
> +{
> + return iova_rcache_range();
> +}
> +
> static const struct dma_map_ops iommu_dma_ops = {
> .alloc = iommu_dma_alloc,
> .free = iommu_dma_free,
> @@ -1462,6 +1467,7 @@ static const struct dma_map_ops iommu_dma_ops = {
> .map_resource = iommu_dma_map_resource,
> .unmap_resource = iommu_dma_unmap_resource,
> .get_merge_boundary = iommu_dma_get_merge_boundary,
> + .opt_mapping_size = iommu_dma_opt_mapping_size,
> };
>
> /*
> diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
> index db77aa675145..9f00b58d546e 100644
> --- a/drivers/iommu/iova.c
> +++ b/drivers/iommu/iova.c
> @@ -26,6 +26,11 @@ static unsigned long iova_rcache_get(struct iova_domain *iovad,
> static void free_cpu_cached_iovas(unsigned int cpu, struct iova_domain *iovad);
> static void free_iova_rcaches(struct iova_domain *iovad);
>
> +unsigned long iova_rcache_range(void)
> +{
> + return PAGE_SIZE << (IOVA_RANGE_CACHE_MAX_SIZE - 1);
> +}
> +
> static int iova_cpuhp_dead(unsigned int cpu, struct hlist_node *node)
> {
> struct iova_domain *iovad;
> diff --git a/include/linux/iova.h b/include/linux/iova.h
> index 320a70e40233..c6ba6d95d79c 100644
> --- a/include/linux/iova.h
> +++ b/include/linux/iova.h
> @@ -79,6 +79,8 @@ static inline unsigned long iova_pfn(struct iova_domain *iovad, dma_addr_t iova)
> int iova_cache_get(void);
> void iova_cache_put(void);
>
> +unsigned long iova_rcache_range(void);
> +
> void free_iova(struct iova_domain *iovad, unsigned long pfn);
> void __free_iova(struct iova_domain *iovad, struct iova *iova);
> struct iova *alloc_iova(struct iova_domain *iovad, unsigned long size,
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
--
Damien Le Moal
Western Digital Research
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next prev parent reply other threads:[~2022-05-26 22:57 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-26 10:28 [PATCH v2 0/4] DMA mapping changes for SCSI core John Garry via iommu
2022-05-26 10:28 ` [PATCH v2 1/4] dma-mapping: Add dma_opt_mapping_size() John Garry via iommu
2022-05-26 10:28 ` [PATCH v2 2/4] dma-iommu: Add iommu_dma_opt_mapping_size() John Garry via iommu
2022-05-26 22:56 ` Damien Le Moal via iommu [this message]
2022-05-26 10:28 ` [PATCH v2 3/4] scsi: core: Cap shost max_sectors according to DMA optimum mapping limits John Garry via iommu
2022-05-26 10:28 ` [PATCH v2 4/4] libata-scsi: Cap ata_device->max_sectors according to shost->max_sectors John Garry via iommu
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