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Message-Id: <20201106170036.18713-8-logang@deltatee.com>
Date: Fri, 6 Nov 2020 10:00:28 -0700
From: Logan Gunthorpe <logang@...tatee.com>
To: linux-kernel@...r.kernel.org, linux-nvme@...ts.infradead.org,
linux-block@...r.kernel.org, linux-pci@...r.kernel.org,
linux-mm@...ck.org, iommu@...ts.linux-foundation.org
Cc: Stephen Bates <sbates@...thlin.com>,
Christoph Hellwig <hch@....de>,
Dan Williams <dan.j.williams@...el.com>,
Jason Gunthorpe <jgg@...pe.ca>,
Christian König <christian.koenig@....com>,
Ira Weiny <iweiny@...el.com>,
John Hubbard <jhubbard@...dia.com>,
Don Dutile <ddutile@...hat.com>,
Matthew Wilcox <willy@...radead.org>,
Daniel Vetter <daniel.vetter@...ll.ch>,
Logan Gunthorpe <logang@...tatee.com>
Subject: [RFC PATCH 07/15] iommu/dma: Support PCI P2PDMA pages in dma-iommu map_sg
When a PCI P2PDMA page is seen, set the IOVA length of the segment
to zero so that it is not mapped into the IOVA. Then, in finalise_sg(),
apply the appropriate bus address to the segment. The IOVA is not
created if the scatterlist only consists of P2PDMA pages.
Similar to dma-direct, DMA_ATTR_P2PDMA is used to indicate caller
support seeing the high bit of the dma_length is used as a flag
to indicate P2PDMA segments.
On unmap, P2PDMA segments are skipped over when determining the
start and end IOVA addresses.
With this change, the flags variable in the dma_map_ops is
set to DMA_F_PCI_P2PDMA_SUPPORTED to indicate support for
P2PDMA pages.
Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
---
drivers/iommu/dma-iommu.c | 63 ++++++++++++++++++++++++++++++++-------
1 file changed, 53 insertions(+), 10 deletions(-)
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 5591d6593583..1c8402474376 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -20,6 +20,7 @@
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/pci.h>
+#include <linux/pci-p2pdma.h>
#include <linux/swiotlb.h>
#include <linux/scatterlist.h>
#include <linux/vmalloc.h>
@@ -872,13 +873,16 @@ static void iommu_dma_unmap_page(struct device *dev, dma_addr_t dma_handle,
* segment's start address to avoid concatenating across one.
*/
static int __finalise_sg(struct device *dev, struct scatterlist *sg, int nents,
- dma_addr_t dma_addr)
+ dma_addr_t dma_addr, unsigned long attrs)
{
struct scatterlist *s, *cur = sg;
unsigned long seg_mask = dma_get_seg_boundary(dev);
unsigned int cur_len = 0, max_len = dma_get_max_seg_size(dev);
int i, count = 0;
+ if (attrs & DMA_ATTR_P2PDMA && max_len >= SG_P2PDMA_FLAG)
+ max_len = SG_P2PDMA_FLAG - 1;
+
/*
* The Intel graphic driver is used to assume that the returned
* sg list is not combound. This blocks the efforts of converting
@@ -917,6 +921,19 @@ static int __finalise_sg(struct device *dev, struct scatterlist *sg, int nents,
sg_dma_address(s) = DMA_MAPPING_ERROR;
sg_dma_len(s) = 0;
+ if (is_pci_p2pdma_page(sg_page(s)) && !s_iova_len) {
+ if (i > 0)
+ cur = sg_next(cur);
+
+ sg_dma_address(cur) = sg_phys(s) + s->offset -
+ pci_p2pdma_bus_offset(sg_page(s));
+ sg_dma_len(cur) = s->length | SG_P2PDMA_FLAG;
+
+ count++;
+ cur_len = 0;
+ continue;
+ }
+
/*
* Now fill in the real DMA data. If...
* - there is a valid output segment to append to
@@ -1013,11 +1030,12 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
struct iommu_dma_cookie *cookie = domain->iova_cookie;
struct iova_domain *iovad = &cookie->iovad;
struct scatterlist *s, *prev = NULL;
+ struct dev_pagemap *pgmap = NULL;
int prot = dma_info_to_prot(dir, dev_is_dma_coherent(dev), attrs);
dma_addr_t iova;
size_t iova_len = 0;
unsigned long mask = dma_get_seg_boundary(dev);
- int i;
+ int i, map = -1;
if (unlikely(iommu_dma_deferred_attach(dev, domain)))
return 0;
@@ -1045,6 +1063,21 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
s_length = iova_align(iovad, s_length + s_iova_off);
s->length = s_length;
+ if (is_pci_p2pdma_page(sg_page(s))) {
+ if (sg_page(s)->pgmap != pgmap) {
+ pgmap = sg_page(s)->pgmap;
+ map = pci_p2pdma_should_map_bus(dev, pgmap);
+ }
+
+ if (map < 0 || !(attrs & DMA_ATTR_P2PDMA))
+ goto out_restore_sg;
+
+ if (map) {
+ s->length = 0;
+ continue;
+ }
+ }
+
/*
* Due to the alignment of our single IOVA allocation, we can
* depend on these assumptions about the segment boundary mask:
@@ -1067,6 +1100,9 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
prev = s;
}
+ if (!iova_len)
+ return __finalise_sg(dev, sg, nents, 0, attrs);
+
iova = iommu_dma_alloc_iova(domain, iova_len, dma_get_mask(dev), dev);
if (!iova)
goto out_restore_sg;
@@ -1078,7 +1114,7 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
if (iommu_map_sg_atomic(domain, iova, sg, nents, prot) < iova_len)
goto out_free_iova;
- return __finalise_sg(dev, sg, nents, iova);
+ return __finalise_sg(dev, sg, nents, iova, attrs);
out_free_iova:
iommu_dma_free_iova(cookie, iova, iova_len, NULL);
@@ -1090,7 +1126,7 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
static void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
int nents, enum dma_data_direction dir, unsigned long attrs)
{
- dma_addr_t start, end;
+ dma_addr_t end, start = DMA_MAPPING_ERROR;
struct scatterlist *tmp;
int i;
@@ -1106,14 +1142,20 @@ static void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
* The scatterlist segments are mapped into a single
* contiguous IOVA allocation, so this is incredibly easy.
*/
- start = sg_dma_address(sg);
- for_each_sg(sg_next(sg), tmp, nents - 1, i) {
- if (sg_dma_len(tmp) == 0)
+ for_each_sg(sg, tmp, nents, i) {
+ if ((attrs & DMA_ATTR_P2PDMA) && sg_dma_is_p2pdma(tmp))
+ continue;
+ if (sg_dma_p2pdma_len(tmp) == 0)
break;
- sg = tmp;
+
+ if (start == DMA_MAPPING_ERROR)
+ start = sg_dma_address(tmp);
+
+ end = sg_dma_address(tmp) + sg_dma_len(tmp);
}
- end = sg_dma_address(sg) + sg_dma_len(sg);
- __iommu_dma_unmap(dev, start, end - start);
+
+ if (start != DMA_MAPPING_ERROR)
+ __iommu_dma_unmap(dev, start, end - start);
}
static dma_addr_t iommu_dma_map_resource(struct device *dev, phys_addr_t phys,
@@ -1334,6 +1376,7 @@ static unsigned long iommu_dma_get_merge_boundary(struct device *dev)
}
static const struct dma_map_ops iommu_dma_ops = {
+ .flags = DMA_F_PCI_P2PDMA_SUPPORTED,
.alloc = iommu_dma_alloc,
.free = iommu_dma_free,
.alloc_pages = dma_common_alloc_pages,
--
2.20.1
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