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From: Robin Murphy <robin.murphy@arm.com>
To: Dmitry Osipenko <digetx@gmail.com>,
	Joerg Roedel <joro@8bytes.org>,
	Thierry Reding <thierry.reding@gmail.com>,
	Jonathan Hunter <jonathanh@nvidia.com>
Cc: linux-tegra@vger.kernel.org, iommu@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 8/9] iommu: Introduce iotlb_sync_map callback
Date: Fri, 11 May 2018 14:02:04 +0100	[thread overview]
Message-ID: <da823a61-5bda-042b-c61f-d0d98f9b6e6f@arm.com> (raw)
In-Reply-To: <20180508181700.5169-9-digetx@gmail.com>

On 08/05/18 19:16, Dmitry Osipenko wrote:
> Introduce iotlb_sync_map() callback that is invoked in the end of
> iommu_map(). This new callback allows IOMMU drivers to avoid syncing
> on mapping of each contiguous chunk and sync only when whole mapping
> is completed, optimizing performance of the mapping operation.

This looks like a reasonable compromise - for users of 
IO_PGTABLE_QUIRK_TLBI_ON_MAP we can leave the implicit add_flush() in 
place for each individual map call, but at least move the sync() out to 
this callback, which should still be beneficial overall.

Modulo one possible nit below,

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>   drivers/iommu/iommu.c | 8 ++++++--
>   include/linux/iommu.h | 1 +
>   2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index d2aa23202bb9..39b2ee66aa96 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1508,13 +1508,14 @@ static size_t iommu_pgsize(struct iommu_domain *domain,
>   int iommu_map(struct iommu_domain *domain, unsigned long iova,
>   	      phys_addr_t paddr, size_t size, int prot)
>   {
> +	const struct iommu_ops *ops = domain->ops;
>   	unsigned long orig_iova = iova;
>   	unsigned int min_pagesz;
>   	size_t orig_size = size;
>   	phys_addr_t orig_paddr = paddr;
>   	int ret = 0;
>   
> -	if (unlikely(domain->ops->map == NULL ||
> +	if (unlikely(ops->map == NULL ||
>   		     domain->pgsize_bitmap == 0UL))
>   		return -ENODEV;
>   
> @@ -1543,7 +1544,7 @@ int iommu_map(struct iommu_domain *domain, unsigned long iova,
>   		pr_debug("mapping: iova 0x%lx pa %pa pgsize 0x%zx\n",
>   			 iova, &paddr, pgsize);
>   
> -		ret = domain->ops->map(domain, iova, paddr, pgsize, prot);
> +		ret = ops->map(domain, iova, paddr, pgsize, prot);
>   		if (ret)
>   			break;
>   
> @@ -1552,6 +1553,9 @@ int iommu_map(struct iommu_domain *domain, unsigned long iova,
>   		size -= pgsize;
>   	}
>   
> +	if (ops->iotlb_sync_map)
> +		ops->iotlb_sync_map(domain);

Is it worth trying to skip this in the error case when we're just going 
to undo it immediately?

Robin.

> +
>   	/* unroll mapping in case something went wrong */
>   	if (ret)
>   		iommu_unmap(domain, orig_iova, orig_size - size);
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 19938ee6eb31..5224aa376377 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -206,6 +206,7 @@ struct iommu_ops {
>   	void (*flush_iotlb_all)(struct iommu_domain *domain);
>   	void (*iotlb_range_add)(struct iommu_domain *domain,
>   				unsigned long iova, size_t size);
> +	void (*iotlb_sync_map)(struct iommu_domain *domain);
>   	void (*iotlb_sync)(struct iommu_domain *domain);
>   	phys_addr_t (*iova_to_phys)(struct iommu_domain *domain, dma_addr_t iova);
>   	int (*add_device)(struct device *dev);
> 

  reply	other threads:[~2018-05-11 13:02 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-08 18:16 [PATCH v1 0/9] Tegra GART driver clean up and optimization Dmitry Osipenko
2018-05-08 18:16 ` [PATCH v1 1/9] memory: tegra: Provide facility for integration with the GART driver Dmitry Osipenko
2018-05-08 18:16 ` [PATCH v1 2/9] iommu/tegra: gart: Provide access to Memory Controller driver Dmitry Osipenko
2018-05-08 18:16 ` [PATCH v1 3/9] iommu/tegra: gart: Remove code related to module unloading Dmitry Osipenko
2018-05-08 18:16 ` [PATCH v1 4/9] iommu/tegra: gart: Remove pr_fmt and clean up includes Dmitry Osipenko
2018-05-08 18:16 ` [PATCH v1 5/9] iommu/tegra: gart: Clean up driver probe failure unwinding Dmitry Osipenko
2018-05-08 18:16 ` [PATCH v1 6/9] iommu/tegra: gart: Ignore devices without IOMMU phandle in DT Dmitry Osipenko
2018-05-11 11:34   ` Robin Murphy
2018-05-11 15:34     ` Dmitry Osipenko
2018-05-08 18:16 ` [PATCH v1 7/9] iommu/tegra: gart: Provide single domain and group for all devices Dmitry Osipenko
2018-05-11 11:12   ` Dmitry Osipenko
2018-05-11 12:32   ` Robin Murphy
2018-05-11 20:05     ` Dmitry Osipenko
2018-05-14 18:18       ` Robin Murphy
2018-05-16 13:43         ` Dmitry Osipenko
2018-05-08 18:16 ` [PATCH v1 8/9] iommu: Introduce iotlb_sync_map callback Dmitry Osipenko
2018-05-11 13:02   ` Robin Murphy [this message]
2018-05-11 19:58     ` Dmitry Osipenko
2018-05-08 18:17 ` [PATCH v1 9/9] iommu/tegra: gart: Optimize mapping / unmapping performance Dmitry Osipenko

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