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dma-buf: move system_cc_shared heap under separate Kconfig

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While system heap and system_cc_shared heap share a lot of code
and hence the same source file, their users have different needs.

system heap users need it to be a loadable module, while
system_cc_shared heap users don't.

Building as a loadable module breaks system_cc_shared heap on
powerpc and s390 due to un-exported set_memory_encrypted /
set_memory_decrypted functions.

Fix these by reorganising code to put the system_cc_shared heap
under a new Kconfig symbol, which allows either building both
into the kernel, or leave encryption up to the consumers of the
system heap.

Fixes: fd55edff8a ("dma-buf: heaps: system: Turn the heap into a module")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
  [sumits: updated DMABUF_HEAPS_CC_SYSTEM to DMABUF_HEAPS_SYSTEM_CC_SHARED]
Reviewed-by: T.J. Mercier <tjmercier@google.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://patch.msgid.link/20260610142329.3836808-1-sumit.semwal@linaro.org
This commit is contained in:
Arnd Bergmann 2026-06-10 19:53:29 +05:30 committed by Sumit Semwal
parent 2db6ddf1cb
commit f7606400f1
2 changed files with 18 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
drivers/dma-buf/heaps/Kconfig
View File

@ -5,6 +5,14 @@ config DMABUF_HEAPS_SYSTEM
Choose this option to enable the system dmabuf heap. The system heap
is backed by pages from the buddy allocator. If in doubt, say Y.
config DMABUF_HEAPS_SYSTEM_CC_SHARED
bool "DMA-BUF System Heap for decrypted CoCo VMs"
depends on DMABUF_HEAPS && ARCH_HAS_MEM_ENCRYPT && DMABUF_HEAPS_SYSTEM=y
help
Choose this option to enable the system_cc_shared dmabuf heap. This
allows allocating shared (decrypted) memory for confidential computing
(CoCo) VMs.
config DMABUF_HEAPS_CMA
tristate "DMA-BUF CMA Heap"
depends on DMABUF_HEAPS && DMA_CMA

16
drivers/dma-buf/heaps/system_heap.c
View File

@ -48,6 +48,9 @@ struct dma_heap_attachment {
bool cc_shared;
};
#define cc_shared_buffer(b) (IS_ENABLED(CONFIG_DMABUF_HEAPS_SYSTEM_CC_SHARED) && \
(b)->cc_shared)
#define LOW_ORDER_GFP (GFP_HIGHUSER | __GFP_ZERO)
#define HIGH_ORDER_GFP (((GFP_HIGHUSER | __GFP_ZERO | __GFP_NOWARN \
| __GFP_NORETRY) & ~__GFP_RECLAIM) \
@ -161,7 +164,7 @@ static struct sg_table *system_heap_map_dma_buf(struct dma_buf_attachment *attac
unsigned long attrs;
int ret;
attrs = a->cc_shared ? DMA_ATTR_CC_SHARED : 0;
attrs = cc_shared_buffer(a) ? DMA_ATTR_CC_SHARED : 0;
ret = dma_map_sgtable(attachment->dev, table, direction, attrs);
if (ret)
return ERR_PTR(ret);
@ -233,7 +236,7 @@ static int system_heap_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma)
int i, ret;
prot = vma->vm_page_prot;
if (buffer->cc_shared)
if (cc_shared_buffer(buffer))
prot = pgprot_decrypted(prot);
for_each_sgtable_sg(table, sg, i) {
@ -282,7 +285,7 @@ static void *system_heap_do_vmap(struct system_heap_buffer *buffer)
}
prot = PAGE_KERNEL;
if (buffer->cc_shared)
if (cc_shared_buffer(buffer))
prot = pgprot_decrypted(prot);
vaddr = vmap(pages, npages, VM_MAP, prot);
vfree(pages);
@ -349,7 +352,7 @@ static void system_heap_dma_buf_release(struct dma_buf *dmabuf)
* Intentionally leak pages that cannot be re-encrypted
* to prevent shared memory from being reused.
*/
if (buffer->cc_shared &&
if (cc_shared_buffer(buffer) &&
system_heap_set_page_encrypted(page))
continue;
@ -456,7 +459,7 @@ static struct dma_buf *system_heap_allocate(struct dma_heap *heap,
list_del(&page->lru);
}
if (cc_shared) {
if (cc_shared_buffer(buffer)) {
for_each_sgtable_sg(table, sg, i) {
ret = system_heap_set_page_decrypted(sg_page(sg));
if (ret)
@ -485,7 +488,7 @@ static struct dma_buf *system_heap_allocate(struct dma_heap *heap,
* Intentionally leak pages that cannot be re-encrypted
* to prevent shared memory from being reused.
*/
if (buffer->cc_shared &&
if (cc_shared_buffer(buffer) &&
system_heap_set_page_encrypted(p))
continue;
__free_pages(p, compound_order(p));
@ -525,6 +528,7 @@ static int __init system_heap_create(void)
return PTR_ERR(sys_heap);
if (IS_ENABLED(CONFIG_HIGHMEM) ||
!IS_ENABLED(CONFIG_DMABUF_HEAPS_SYSTEM_CC_SHARED) ||
!cc_platform_has(CC_ATTR_MEM_ENCRYPT))
return 0;