udmabuf: fix vmap_udmabuf error page set

Currently vmap_udmabuf set page's array by each folio.
But, ubuf->folios is only contain's the folio's head page.

That mean we repeatedly mapped the folio head page to the vmalloc area.

Due to udmabuf can use hugetlb, if HVO enabled, tail page may not exist,
so, we can't use page array to map, instead, use pfn array.

By this, we removed page usage in udmabuf totally.

Fixes: 5e72b2b41a21 ("udmabuf: convert udmabuf driver to use folios")
Suggested-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Signed-off-by: Huan Yang <link@vivo.com>
Acked-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240918025238.2957823-4-link@vivo.com

diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig
index b46eb8a552d7be02cb305f65aaf4ba168f03fee2..fee04fdb08220c1ea745bdf56802a0d1d9b231a5 100644 (file)
--- a/drivers/dma-buf/Kconfig
+++ b/drivers/dma-buf/Kconfig
@@ -36,6 +36,7 @@ config UDMABUF
        depends on DMA_SHARED_BUFFER
        depends on MEMFD_CREATE || COMPILE_TEST
        depends on MMU
+       select VMAP_PFN
        help
          A driver to let userspace turn memfd regions into dma-bufs.
          Qemu can use this to create host dmabufs for guest framebuffers.

diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index ba9dbc7caf71416fc2da0ca8cc3c589737d671a7..aa182a9dcdfac5dd9da1995bd895119103a4eb1c 100644 (file)
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -103,21 +103,29 @@ static int mmap_udmabuf(struct dma_buf *buf, struct vm_area_struct *vma)
 static int vmap_udmabuf(struct dma_buf *buf, struct iosys_map *map)
 {
        struct udmabuf *ubuf = buf->priv;
-       struct page **pages;
+       unsigned long *pfns;
        void *vaddr;
        pgoff_t pg;
 
        dma_resv_assert_held(buf->resv);
 
-       pages = kvmalloc_array(ubuf->pagecount, sizeof(*pages), GFP_KERNEL);
-       if (!pages)
+       /**
+        * HVO may free tail pages, so just use pfn to map each folio
+        * into vmalloc area.
+        */
+       pfns = kvmalloc_array(ubuf->pagecount, sizeof(*pfns), GFP_KERNEL);
+       if (!pfns)
                return -ENOMEM;
 
-       for (pg = 0; pg < ubuf->pagecount; pg++)
-               pages[pg] = &ubuf->folios[pg]->page;
+       for (pg = 0; pg < ubuf->pagecount; pg++) {
+               unsigned long pfn = folio_pfn(ubuf->folios[pg]);
 
-       vaddr = vm_map_ram(pages, ubuf->pagecount, -1);
-       kvfree(pages);
+               pfn += ubuf->offsets[pg] >> PAGE_SHIFT;
+               pfns[pg] = pfn;
+       }
+
+       vaddr = vmap_pfn(pfns, ubuf->pagecount, PAGE_KERNEL);
+       kvfree(pfns);
        if (!vaddr)
                return -EINVAL;