[v1] Remove DMA .map_page and .unmap_page callbacks

[PATCH v1 1/9] alpha: Convert mapping routine to rely on physical address

Posted by Leon Romanovsky 3 days, 6 hours ago

From: Leon Romanovsky <leonro@nvidia.com>

Alpha doesn't need struct *page and can perform mapping based on
physical addresses. So convert it to implement new .map_phys callback.

As part of this change, remove useless BUG_ON() as DMA mapping layer
ensures that right direction is provided.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 arch/alpha/kernel/pci_iommu.c | 48 +++++++++++++++--------------------
 1 file changed, 21 insertions(+), 27 deletions(-)

diff --git a/arch/alpha/kernel/pci_iommu.c b/arch/alpha/kernel/pci_iommu.c
index dc91de50f906..3e4f631a1f27 100644
--- a/arch/alpha/kernel/pci_iommu.c
+++ b/arch/alpha/kernel/pci_iommu.c
@@ -224,28 +224,26 @@ static int pci_dac_dma_supported(struct pci_dev *dev, u64 mask)
    until either pci_unmap_single or pci_dma_sync_single is performed.  */
 
 static dma_addr_t
-pci_map_single_1(struct pci_dev *pdev, void *cpu_addr, size_t size,
+pci_map_single_1(struct pci_dev *pdev, phys_addr_t paddr, size_t size,
 		 int dac_allowed)
 {
 	struct pci_controller *hose = pdev ? pdev->sysdata : pci_isa_hose;
 	dma_addr_t max_dma = pdev ? pdev->dma_mask : ISA_DMA_MASK;
+	unsigned long offset = offset_in_page(paddr);
 	struct pci_iommu_arena *arena;
 	long npages, dma_ofs, i;
-	unsigned long paddr;
 	dma_addr_t ret;
 	unsigned int align = 0;
 	struct device *dev = pdev ? &pdev->dev : NULL;
 
-	paddr = __pa(cpu_addr);
-
 #if !DEBUG_NODIRECT
 	/* First check to see if we can use the direct map window.  */
 	if (paddr + size + __direct_map_base - 1 <= max_dma
 	    && paddr + size <= __direct_map_size) {
 		ret = paddr + __direct_map_base;
 
-		DBGA2("pci_map_single: [%p,%zx] -> direct %llx from %ps\n",
-		      cpu_addr, size, ret, __builtin_return_address(0));
+		DBGA2("pci_map_single: [%pa,%zx] -> direct %llx from %ps\n",
+		      &paddr, size, ret, __builtin_return_address(0));
 
 		return ret;
 	}
@@ -255,8 +253,8 @@ pci_map_single_1(struct pci_dev *pdev, void *cpu_addr, size_t size,
 	if (dac_allowed) {
 		ret = paddr + alpha_mv.pci_dac_offset;
 
-		DBGA2("pci_map_single: [%p,%zx] -> DAC %llx from %ps\n",
-		      cpu_addr, size, ret, __builtin_return_address(0));
+		DBGA2("pci_map_single: [%pa,%zx] -> DAC %llx from %ps\n",
+		      &paddr, size, ret, __builtin_return_address(0));
 
 		return ret;
 	}
@@ -290,10 +288,10 @@ pci_map_single_1(struct pci_dev *pdev, void *cpu_addr, size_t size,
 		arena->ptes[i + dma_ofs] = mk_iommu_pte(paddr);
 
 	ret = arena->dma_base + dma_ofs * PAGE_SIZE;
-	ret += (unsigned long)cpu_addr & ~PAGE_MASK;
+	ret += offset;
 
-	DBGA2("pci_map_single: [%p,%zx] np %ld -> sg %llx from %ps\n",
-	      cpu_addr, size, npages, ret, __builtin_return_address(0));
+	DBGA2("pci_map_single: [%pa,%zx] np %ld -> sg %llx from %ps\n",
+	      &paddr, size, npages, ret, __builtin_return_address(0));
 
 	return ret;
 }
@@ -322,19 +320,18 @@ static struct pci_dev *alpha_gendev_to_pci(struct device *dev)
 	return NULL;
 }
 
-static dma_addr_t alpha_pci_map_page(struct device *dev, struct page *page,
-				     unsigned long offset, size_t size,
-				     enum dma_data_direction dir,
+static dma_addr_t alpha_pci_map_phys(struct device *dev, phys_addr_t phys,
+				     size_t size, enum dma_data_direction dir,
 				     unsigned long attrs)
 {
 	struct pci_dev *pdev = alpha_gendev_to_pci(dev);
 	int dac_allowed;
 
-	BUG_ON(dir == DMA_NONE);
+	if (attrs & DMA_ATTR_MMIO)
+		return DMA_MAPPING_ERROR;
 
-	dac_allowed = pdev ? pci_dac_dma_supported(pdev, pdev->dma_mask) : 0; 
-	return pci_map_single_1(pdev, (char *)page_address(page) + offset, 
-				size, dac_allowed);
+	dac_allowed = pdev ? pci_dac_dma_supported(pdev, pdev->dma_mask) : 0;
+	return pci_map_single_1(pdev, phys, size, dac_allowed);
 }
 
 /* Unmap a single streaming mode DMA translation.  The DMA_ADDR and
@@ -343,7 +340,7 @@ static dma_addr_t alpha_pci_map_page(struct device *dev, struct page *page,
    the cpu to the buffer are guaranteed to see whatever the device
    wrote there.  */
 
-static void alpha_pci_unmap_page(struct device *dev, dma_addr_t dma_addr,
+static void alpha_pci_unmap_phys(struct device *dev, dma_addr_t dma_addr,
 				 size_t size, enum dma_data_direction dir,
 				 unsigned long attrs)
 {
@@ -353,8 +350,6 @@ static void alpha_pci_unmap_page(struct device *dev, dma_addr_t dma_addr,
 	struct pci_iommu_arena *arena;
 	long dma_ofs, npages;
 
-	BUG_ON(dir == DMA_NONE);
-
 	if (dma_addr >= __direct_map_base
 	    && dma_addr < __direct_map_base + __direct_map_size) {
 		/* Nothing to do.  */
@@ -429,7 +424,7 @@ static void *alpha_pci_alloc_coherent(struct device *dev, size_t size,
 	}
 	memset(cpu_addr, 0, size);
 
-	*dma_addrp = pci_map_single_1(pdev, cpu_addr, size, 0);
+	*dma_addrp = pci_map_single_1(pdev, virt_to_phys(cpu_addr), size, 0);
 	if (*dma_addrp == DMA_MAPPING_ERROR) {
 		free_pages((unsigned long)cpu_addr, order);
 		if (alpha_mv.mv_pci_tbi || (gfp & GFP_DMA))
@@ -643,9 +638,8 @@ static int alpha_pci_map_sg(struct device *dev, struct scatterlist *sg,
 	/* Fast path single entry scatterlists.  */
 	if (nents == 1) {
 		sg->dma_length = sg->length;
-		sg->dma_address
-		  = pci_map_single_1(pdev, SG_ENT_VIRT_ADDRESS(sg),
-				     sg->length, dac_allowed);
+		sg->dma_address = pci_map_single_1(pdev, sg_phys(sg),
+						   sg->length, dac_allowed);
 		if (sg->dma_address == DMA_MAPPING_ERROR)
 			return -EIO;
 		return 1;
@@ -917,8 +911,8 @@ iommu_unbind(struct pci_iommu_arena *arena, long pg_start, long pg_count)
 const struct dma_map_ops alpha_pci_ops = {
 	.alloc			= alpha_pci_alloc_coherent,
 	.free			= alpha_pci_free_coherent,
-	.map_page		= alpha_pci_map_page,
-	.unmap_page		= alpha_pci_unmap_page,
+	.map_phys		= alpha_pci_map_phys,
+	.unmap_phys		= alpha_pci_unmap_phys,
 	.map_sg			= alpha_pci_map_sg,
 	.unmap_sg		= alpha_pci_unmap_sg,
 	.dma_supported		= alpha_pci_supported,
-- 
2.51.0

Re: [PATCH v1 1/9] alpha: Convert mapping routine to rely on physical address

Posted by Magnus Lindholm 3 days, 3 hours ago

On Sun, Sep 28, 2025 at 5:02 PM Leon Romanovsky <leon@kernel.org> wrote:
>
> From: Leon Romanovsky <leonro@nvidia.com>
>
> Alpha doesn't need struct *page and can perform mapping based on
> physical addresses. So convert it to implement new .map_phys callback.
>
> As part of this change, remove useless BUG_ON() as DMA mapping layer
> ensures that right direction is provided.

After the changes in v1 this runs fine on Alpha. I've tested this on an
ES40 Alphaserver during load (build kernel and unpack tar files).
The v1 patch fixes the errors seen in the first revision of this patch.

Tested-by: Magnus Lindholm <linmag7@gmail.com>

[PATCH v1 1/9] alpha: Convert mapping routine to rely on physical address
[PATCH v1 2/9] MIPS/jazzdma: Provide physical address directly
[PATCH v1 3/9] parisc: Convert DMA map_page to map_phys interface
[PATCH v1 4/9] powerpc: Convert to physical address DMA mapping
[PATCH v1 5/9] sparc64: Use physical address DMA mapping
[PATCH v1 6/9] x86: Use physical address for DMA mapping
[PATCH v1 7/9] vdpa: Convert to physical address DMA mapping
[PATCH v1 8/9] xen: swiotlb: Convert mapping routine to rely on physical address
[PATCH v1 9/9] dma-mapping: remove unused map_page callback