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Date: Tue, 12 Jul 2016 11:55:39 +0100
From: Robin Murphy <robin.murphy@....com>
To: Joerg Roedel <joro@...tes.org>, iommu@...ts.linux-foundation.org
Cc: Vincent.Wan@....com, Joerg Roedel <jroedel@...e.de>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 07/20] iommu/amd: Remove special mapping code for dma_ops
path
Hi Joerg,
On 08/07/16 12:44, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@...e.de>
>
> Use the iommu-api map/unmap functions instead. This will be
> required anyway when IOVA code is used for address
> allocation.
>
> Signed-off-by: Joerg Roedel <jroedel@...e.de>
> ---
> drivers/iommu/amd_iommu.c | 107 ++++++----------------------------------------
> 1 file changed, 14 insertions(+), 93 deletions(-)
>
> diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
> index e7c042b..08aa46c 100644
> --- a/drivers/iommu/amd_iommu.c
> +++ b/drivers/iommu/amd_iommu.c
> @@ -2557,94 +2557,6 @@ static void update_domain(struct protection_domain *domain)
> }
>
> /*
> - * This function fetches the PTE for a given address in the aperture
> - */
> -static u64* dma_ops_get_pte(struct dma_ops_domain *dom,
> - unsigned long address)
> -{
> - struct aperture_range *aperture;
> - u64 *pte, *pte_page;
> -
> - aperture = dom->aperture[APERTURE_RANGE_INDEX(address)];
> - if (!aperture)
> - return NULL;
> -
> - pte = aperture->pte_pages[APERTURE_PAGE_INDEX(address)];
> - if (!pte) {
> - pte = alloc_pte(&dom->domain, address, PAGE_SIZE, &pte_page,
> - GFP_ATOMIC);
> - aperture->pte_pages[APERTURE_PAGE_INDEX(address)] = pte_page;
> - } else
> - pte += PM_LEVEL_INDEX(0, address);
> -
> - update_domain(&dom->domain);
> -
> - return pte;
> -}
> -
> -/*
> - * This is the generic map function. It maps one 4kb page at paddr to
> - * the given address in the DMA address space for the domain.
> - */
> -static dma_addr_t dma_ops_domain_map(struct dma_ops_domain *dom,
> - unsigned long address,
> - phys_addr_t paddr,
> - int direction)
> -{
> - u64 *pte, __pte;
> -
> - WARN_ON(address > dom->aperture_size);
> -
> - paddr &= PAGE_MASK;
> -
> - pte = dma_ops_get_pte(dom, address);
> - if (!pte)
> - return DMA_ERROR_CODE;
> -
> - __pte = paddr | IOMMU_PTE_P | IOMMU_PTE_FC;
> -
> - if (direction == DMA_TO_DEVICE)
> - __pte |= IOMMU_PTE_IR;
> - else if (direction == DMA_FROM_DEVICE)
> - __pte |= IOMMU_PTE_IW;
> - else if (direction == DMA_BIDIRECTIONAL)
> - __pte |= IOMMU_PTE_IR | IOMMU_PTE_IW;
> -
> - WARN_ON_ONCE(*pte);
> -
> - *pte = __pte;
> -
> - return (dma_addr_t)address;
> -}
> -
> -/*
> - * The generic unmapping function for on page in the DMA address space.
> - */
> -static void dma_ops_domain_unmap(struct dma_ops_domain *dom,
> - unsigned long address)
> -{
> - struct aperture_range *aperture;
> - u64 *pte;
> -
> - if (address >= dom->aperture_size)
> - return;
> -
> - aperture = dom->aperture[APERTURE_RANGE_INDEX(address)];
> - if (!aperture)
> - return;
> -
> - pte = aperture->pte_pages[APERTURE_PAGE_INDEX(address)];
> - if (!pte)
> - return;
> -
> - pte += PM_LEVEL_INDEX(0, address);
> -
> - WARN_ON_ONCE(!*pte);
> -
> - *pte = 0ULL;
> -}
> -
> -/*
> * This function contains common code for mapping of a physically
> * contiguous memory region into DMA address space. It is used by all
> * mapping functions provided with this IOMMU driver.
> @@ -2654,7 +2566,7 @@ static dma_addr_t __map_single(struct device *dev,
> struct dma_ops_domain *dma_dom,
> phys_addr_t paddr,
> size_t size,
> - int dir,
> + int direction,
> bool align,
> u64 dma_mask)
> {
> @@ -2662,6 +2574,7 @@ static dma_addr_t __map_single(struct device *dev,
> dma_addr_t address, start, ret;
> unsigned int pages;
> unsigned long align_mask = 0;
> + int prot = 0;
> int i;
>
> pages = iommu_num_pages(paddr, size, PAGE_SIZE);
> @@ -2676,10 +2589,18 @@ static dma_addr_t __map_single(struct device *dev,
> if (address == DMA_ERROR_CODE)
> goto out;
>
> + if (direction == DMA_TO_DEVICE)
> + prot = IOMMU_PROT_IR;
> + else if (direction == DMA_FROM_DEVICE)
> + prot = IOMMU_PROT_IW;
> + else if (direction == DMA_BIDIRECTIONAL)
> + prot = IOMMU_PROT_IW | IOMMU_PROT_IR;
> +
> start = address;
> for (i = 0; i < pages; ++i) {
> - ret = dma_ops_domain_map(dma_dom, start, paddr, dir);
> - if (ret == DMA_ERROR_CODE)
> + ret = iommu_map_page(&dma_dom->domain, start, paddr,
> + PAGE_SIZE, prot, GFP_ATOMIC);
I see that amd_iommu_map/unmap() takes a lock around calling
iommu_map/unmap_page(), but we don't appear to do that here. That seems
to suggest that either one is unsafe or the other is unnecessary.
Robin.
> + if (ret)
> goto out_unmap;
>
> paddr += PAGE_SIZE;
> @@ -2699,7 +2620,7 @@ out_unmap:
>
> for (--i; i >= 0; --i) {
> start -= PAGE_SIZE;
> - dma_ops_domain_unmap(dma_dom, start);
> + iommu_unmap_page(&dma_dom->domain, start, PAGE_SIZE);
> }
>
> dma_ops_free_addresses(dma_dom, address, pages);
> @@ -2730,7 +2651,7 @@ static void __unmap_single(struct dma_ops_domain *dma_dom,
> start = dma_addr;
>
> for (i = 0; i < pages; ++i) {
> - dma_ops_domain_unmap(dma_dom, start);
> + iommu_unmap_page(&dma_dom->domain, start, PAGE_SIZE);
> start += PAGE_SIZE;
> }
>
>
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