udmabuf: fix vmap_udmabuf error page set

[ Upstream commit 18d7de823b7150344d242c3677e65d68c5271b04 ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>

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 bc94c194e172dc4e899a8dbb4749adb056630d66..a3638ccc15f571ac297775dee0ea97b0f620334f 100644 (file)
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -74,21 +74,29 @@ 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;