Messages in this thread | | | Date | Tue, 24 Nov 2020 16:46:45 -0500 | From | Konrad Rzeszutek Wilk <> | Subject | Re: [PATCH] [PATCH] Adding offset keeping option when mapping data via SWIOTLB. |
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On Mon, Nov 23, 2020 at 02:18:07PM -0800, Jianxiong Gao wrote: > NVMe driver and other applications may depend on the data offset > to operate correctly. Currently when unaligned data is mapped via > SWIOTLB, the data is mapped as slab aligned with the SWIOTLB. When > booting with --swiotlb=force option and using NVMe as interface, > running mkfs.xfs on Rhel fails because of the unalignment issue.
RHEL? So a specific RHEL kernel. Is there a Red Hat bug created for this that can be linked to this patch to make it easier for folks to figure this?
Why would you be using swiotlb=force? Ah, you are using AMD SEV!
> This patch adds an option to make sure the mapped data preserves > its offset of the orginal addrss. Tested on latest kernel that
s/addrss/address/ > this patch fixes the issue. > > Signed-off-by: Jianxiong Gao <jxgao@google.com> > Acked-by: David Rientjes <rientjes@google.com> > --- > drivers/nvme/host/pci.c | 3 ++- > include/linux/dma-mapping.h | 8 ++++++++ > kernel/dma/swiotlb.c | 13 +++++++++++++ > 3 files changed, 23 insertions(+), 1 deletion(-) > > diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c > index 0578ff253c47..a366fb8a1ff0 100644 > --- a/drivers/nvme/host/pci.c > +++ b/drivers/nvme/host/pci.c > @@ -833,7 +833,8 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req, > iod->nents, rq_dma_dir(req), DMA_ATTR_NO_WARN); > else > nr_mapped = dma_map_sg_attrs(dev->dev, iod->sg, iod->nents, > - rq_dma_dir(req), DMA_ATTR_NO_WARN); > + rq_dma_dir(req), > + DMA_ATTR_NO_WARN|DMA_ATTR_SWIOTLB_KEEP_OFFSET); > if (!nr_mapped) > goto out; > > diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h > index 956151052d45..e46d23d9fa20 100644 > --- a/include/linux/dma-mapping.h > +++ b/include/linux/dma-mapping.h > @@ -61,6 +61,14 @@ > */ > #define DMA_ATTR_PRIVILEGED (1UL << 9) > > +/* > + * DMA_ATTR_SWIOTLB_KEEP_OFFSET: used to indicate that the buffer has to keep > + * its offset when mapped via SWIOTLB. Some application functionality depends > + * on the address offset, thus when buffers are mapped via SWIOTLB, the offset > + * needs to be preserved. > + */ > +#define DMA_ATTR_SWIOTLB_KEEP_OFFSET (1UL << 10) > + > /* > * A dma_addr_t can hold any valid DMA or bus address for the platform. It can > * be given to a device to use as a DMA source or target. It is specific to a > diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c > index 781b9dca197c..f43d7be1342d 100644 > --- a/kernel/dma/swiotlb.c > +++ b/kernel/dma/swiotlb.c > @@ -483,6 +483,13 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr, > max_slots = mask + 1 > ? ALIGN(mask + 1, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT > : 1UL << (BITS_PER_LONG - IO_TLB_SHIFT); > + > + /* > + * If we need to keep the offset when mapping, we need to add the offset > + * to the total set we need to allocate in SWIOTLB > + */ > + if (attrs & DMA_ATTR_SWIOTLB_KEEP_OFFSET) > + alloc_size += offset_in_page(orig_addr); > > /* > * For mappings greater than or equal to a page, we limit the stride > @@ -567,6 +574,12 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr, > */ > for (i = 0; i < nslots; i++) > io_tlb_orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT); > + /* > + * When keeping the offset of the original data, we need to advance > + * the tlb_addr by the offset of orig_addr. > + */ > + if (attrs & DMA_ATTR_SWIOTLB_KEEP_OFFSET) > + tlb_addr += orig_addr & (PAGE_SIZE - 1); > if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) && > (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)) > swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_TO_DEVICE); > -- > 2.27.0 > >
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