linux-kernel - [PATCH v8 04/13] dma-mapping: allow EREMOTEIO return code for P2PDMA transfers

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Message-Id: <20220708165104.5005-5-logang@deltatee.com>
Date:   Fri,  8 Jul 2022 10:50:55 -0600
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,
        iommu@...ts.linux.dev
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>,
        John Hubbard <jhubbard@...dia.com>,
        Don Dutile <ddutile@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Minturn Dave B <dave.b.minturn@...el.com>,
        Jason Ekstrand <jason@...kstrand.net>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Xiong Jianxin <jianxin.xiong@...el.com>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Ira Weiny <ira.weiny@...el.com>,
        Robin Murphy <robin.murphy@....com>,
        Martin Oliveira <martin.oliveira@...eticom.com>,
        Chaitanya Kulkarni <ckulkarnilinux@...il.com>,
        Ralph Campbell <rcampbell@...dia.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Jason Gunthorpe <jgg@...dia.com>
Subject: [PATCH v8 04/13] dma-mapping: allow EREMOTEIO return code for P2PDMA transfers

Add EREMOTEIO error return to dma_map_sgtable() which will be used
by .map_sg() implementations that detect P2PDMA pages that the
underlying DMA device cannot access.

Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
Reviewed-by: Christoph Hellwig <hch@....de>
---
 kernel/dma/mapping.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index db7244291b74..20e70fa71091 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -197,7 +197,7 @@ static int __dma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
 	if (ents > 0)
 		debug_dma_map_sg(dev, sg, nents, ents, dir, attrs);
 	else if (WARN_ON_ONCE(ents != -EINVAL && ents != -ENOMEM &&
-			      ents != -EIO))
+			      ents != -EIO && ents != -EREMOTEIO))
 		return -EIO;
 
 	return ents;
@@ -255,6 +255,9 @@ EXPORT_SYMBOL(dma_map_sg_attrs);
  *		complete the mapping. Should succeed if retried later.
  *   -EIO	Legacy error code with an unknown meaning. eg. this is
  *		returned if a lower level call returned DMA_MAPPING_ERROR.
+ *   -EREMOTEIO	The DMA device cannot access P2PDMA memory specified in
+ *		the sg_table. This will not succeed if retried.
+ *
  */
 int dma_map_sgtable(struct device *dev, struct sg_table *sgt,
 		    enum dma_data_direction dir, unsigned long attrs)
-- 
2.30.2