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dma-mapping: move pgprot_decrypted out of dma_pgprot 

pgprot_decrypted is used by AMD SME systems to allow access to memory
that was set to not encrypted using set_memory_decrypted.  That only
happens for dma-direct memory as the IOMMU solves the addressing
challenges for the encryption bit using its own remapping.

Move the pgprot_decrypted call out of dma_pgprot which is also used
by the IOMMU mappings and into dma-direct so that it is only used with
memory that was set decrypted.

Fixes: f5ff79fddf ("dma-mapping: remove CONFIG_DMA_REMAP")
Reported-by: Alex Xu (Hello71) <alex_y_xu@yahoo.ca>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Alex Xu (Hello71) <alex_y_xu@yahoo.ca>
This commit is contained in:
Christoph Hellwig 2022-03-31 08:01:21 +02:00
parent 05b0ebd06a
commit 4fe87e818e
2 changed files with 8 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
kernel/dma/direct.c
View File

@ -277,12 +277,16 @@ void *dma_direct_alloc(struct device *dev, size_t size,
}
if (remap) {
pgprot_t prot = dma_pgprot(dev, PAGE_KERNEL, attrs);
if (force_dma_unencrypted(dev))
prot = pgprot_decrypted(prot);
/* remove any dirty cache lines on the kernel alias */
arch_dma_prep_coherent(page, size);
/* create a coherent mapping */
ret = dma_common_contiguous_remap(page, size,
dma_pgprot(dev, PAGE_KERNEL, attrs),
ret = dma_common_contiguous_remap(page, size, prot,
__builtin_return_address(0));
if (!ret)
goto out_free_pages;
@ -535,6 +539,8 @@ int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma,
int ret = -ENXIO;
vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
if (force_dma_unencrypted(dev))
vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
return ret;

2
kernel/dma/mapping.c
View File

@ -407,8 +407,6 @@ EXPORT_SYMBOL(dma_get_sgtable_attrs);
*/
pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs)
{
if (force_dma_unencrypted(dev))
prot = pgprot_decrypted(prot);
if (dev_is_dma_coherent(dev))
return prot;
#ifdef CONFIG_ARCH_HAS_DMA_WRITE_COMBINE