From: David Rientjes <rientjes@xxxxxxxxxx>
upstream 76a19940bd62a81148c303f3df6d0cee9ae4b509 commit.
When a device requires unencrypted memory and the context does not allow
blocking, memory must be returned from the atomic coherent pools.
This avoids the remap when CONFIG_DMA_DIRECT_REMAP is not enabled and the
config only requires CONFIG_DMA_COHERENT_POOL. This will be used for
CONFIG_AMD_MEM_ENCRYPT in a subsequent patch.
Keep all memory in these pools unencrypted. When set_memory_decrypted()
fails, this prohibits the memory from being added. If adding memory to
the genpool fails, and set_memory_encrypted() subsequently fails, there
is no alternative other than leaking the memory.
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Peter Gonda <pgonda@xxxxxxxxxx>
---
kernel/dma/direct.c | 46 ++++++++++++++++++++++++++++++++++++++-------
kernel/dma/pool.c | 27 +++++++++++++++++++++++---
2 files changed, 63 insertions(+), 10 deletions(-)
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 38266fb2797d..210ea469028c 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -90,6 +90,39 @@ static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
min_not_zero(dev->coherent_dma_mask, dev->bus_dma_mask);
}
+/*
+ * Decrypting memory is allowed to block, so if this device requires
+ * unencrypted memory it must come from atomic pools.
+ */
+static inline bool dma_should_alloc_from_pool(struct device *dev, gfp_t gfp,
+ unsigned long attrs)
+{
+ if (!IS_ENABLED(CONFIG_DMA_COHERENT_POOL))
+ return false;
+ if (gfpflags_allow_blocking(gfp))
+ return false;
+ if (force_dma_unencrypted(dev))
+ return true;
+ if (!IS_ENABLED(CONFIG_DMA_DIRECT_REMAP))
+ return false;
+ if (dma_alloc_need_uncached(dev, attrs))
+ return true;
+ return false;
+}
+
+static inline bool dma_should_free_from_pool(struct device *dev,
+ unsigned long attrs)
+{
+ if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL))
+ return true;
+ if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
+ !force_dma_unencrypted(dev))
+ return false;
+ if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP))
+ return true;
+ return false;
+}
+
struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
gfp_t gfp, unsigned long attrs)
{
@@ -139,9 +172,7 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
struct page *page;
void *ret;
- if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
- dma_alloc_need_uncached(dev, attrs) &&
- !gfpflags_allow_blocking(gfp)) {
+ if (dma_should_alloc_from_pool(dev, gfp, attrs)) {
ret = dma_alloc_from_pool(dev, PAGE_ALIGN(size), &page, gfp);
if (!ret)
return NULL;
@@ -217,6 +248,11 @@ void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,
{
unsigned int page_order = get_order(size);
+ /* If cpu_addr is not from an atomic pool, dma_free_from_pool() fails */
+ if (dma_should_free_from_pool(dev, attrs) &&
+ dma_free_from_pool(dev, cpu_addr, PAGE_ALIGN(size)))
+ return;
+
if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
!force_dma_unencrypted(dev)) {
/* cpu_addr is a struct page cookie, not a kernel address */
@@ -224,10 +260,6 @@ void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,
return;
}
- if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
- dma_free_from_pool(dev, cpu_addr, PAGE_ALIGN(size)))
- return;
-
if (force_dma_unencrypted(dev))
set_memory_encrypted((unsigned long)cpu_addr, 1 << page_order);
diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
index ffe866c2c034..c8d61b3a7bd6 100644
--- a/kernel/dma/pool.c
+++ b/kernel/dma/pool.c
@@ -8,6 +8,7 @@
#include <linux/dma-contiguous.h>
#include <linux/init.h>
#include <linux/genalloc.h>
+#include <linux/set_memory.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
@@ -53,22 +54,42 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
arch_dma_prep_coherent(page, pool_size);
+#ifdef CONFIG_DMA_DIRECT_REMAP
addr = dma_common_contiguous_remap(page, pool_size,
pgprot_dmacoherent(PAGE_KERNEL),
__builtin_return_address(0));
if (!addr)
goto free_page;
-
+#else
+ addr = page_to_virt(page);
+#endif
+ /*
+ * Memory in the atomic DMA pools must be unencrypted, the pools do not
+ * shrink so no re-encryption occurs in dma_direct_free_pages().
+ */
+ ret = set_memory_decrypted((unsigned long)page_to_virt(page),
+ 1 << order);
+ if (ret)
+ goto remove_mapping;
ret = gen_pool_add_virt(pool, (unsigned long)addr, page_to_phys(page),
pool_size, NUMA_NO_NODE);
if (ret)
- goto remove_mapping;
+ goto encrypt_mapping;
return 0;
+encrypt_mapping:
+ ret = set_memory_encrypted((unsigned long)page_to_virt(page),
+ 1 << order);
+ if (WARN_ON_ONCE(ret)) {
+ /* Decrypt succeeded but encrypt failed, purposely leak */
+ goto out;
+ }
remove_mapping:
+#ifdef CONFIG_DMA_DIRECT_REMAP
dma_common_free_remap(addr, pool_size);
-free_page:
+#endif
+free_page: __maybe_unused
if (!dma_release_from_contiguous(NULL, page, 1 << order))
__free_pages(page, order);
out:
--
2.28.0.618.gf4bc123cb7-goog
