[patch for-5.8 1/4] dma-direct: always align allocation size in dma_direct_alloc_pages()

[David Rientjes]

dma_alloc_contiguous() does size >> PAGE_SHIFT and set_memory_decrypted()
works at page granularity.  It's necessary to page align the allocation
size in dma_direct_alloc_pages() for consistent behavior.

This also fixes an issue when arch_dma_prep_coherent() is called on an
unaligned allocation size for dma_alloc_need_uncached() when
CONFIG_DMA_DIRECT_REMAP is disabled but CONFIG_ARCH_HAS_DMA_SET_UNCACHED
is enabled.

Cc: sta...@vger.kernel.org
Signed-off-by: David Rientjes <rient...@google.com>
---
 kernel/dma/direct.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -112,11 +112,12 @@ static inline bool dma_should_free_from_pool(struct 
device *dev,
 struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
                gfp_t gfp, unsigned long attrs)
 {
-       size_t alloc_size = PAGE_ALIGN(size);
        int node = dev_to_node(dev);
        struct page *page = NULL;
        u64 phys_limit;
 
+       VM_BUG_ON(!PAGE_ALIGNED(size));
+
        if (attrs & DMA_ATTR_NO_WARN)
                gfp |= __GFP_NOWARN;
 
@@ -124,14 +125,14 @@ struct page *__dma_direct_alloc_pages(struct device *dev, 
size_t size,
        gfp &= ~__GFP_ZERO;
        gfp |= dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
                                           &phys_limit);
-       page = dma_alloc_contiguous(dev, alloc_size, gfp);
+       page = dma_alloc_contiguous(dev, size, gfp);
        if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
-               dma_free_contiguous(dev, page, alloc_size);
+               dma_free_contiguous(dev, page, size);
                page = NULL;
        }
 again:
        if (!page)
-               page = alloc_pages_node(node, gfp, get_order(alloc_size));
+               page = alloc_pages_node(node, gfp, get_order(size));
        if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
                dma_free_contiguous(dev, page, size);
                page = NULL;
@@ -158,8 +159,10 @@ void *dma_direct_alloc_pages(struct device *dev, size_t 
size,
        struct page *page;
        void *ret;
 
+       size = PAGE_ALIGN(size);
+
        if (dma_should_alloc_from_pool(dev, gfp, attrs)) {
-               ret = dma_alloc_from_pool(dev, PAGE_ALIGN(size), &page, gfp);
+               ret = dma_alloc_from_pool(dev, size, &page, gfp);
                if (!ret)
                        return NULL;
                goto done;
@@ -183,10 +186,10 @@ void *dma_direct_alloc_pages(struct device *dev, size_t 
size,
             dma_alloc_need_uncached(dev, attrs)) ||
            (IS_ENABLED(CONFIG_DMA_REMAP) && PageHighMem(page))) {
                /* remove any dirty cache lines on the kernel alias */
-               arch_dma_prep_coherent(page, PAGE_ALIGN(size));
+               arch_dma_prep_coherent(page, size);
 
                /* create a coherent mapping */
-               ret = dma_common_contiguous_remap(page, PAGE_ALIGN(size),
+               ret = dma_common_contiguous_remap(page, size,
                                dma_pgprot(dev, PAGE_KERNEL, attrs),
                                __builtin_return_address(0));
                if (!ret)