ALSA: usb: qcom: Fix false-positive address space check

The sanity check previously added to uaudio_transfer_buffer_setup()
assumed the allocated buffer being linear-mapped.  But the buffer
allocated via usb_alloc_coherent() isn't always so, rather to be used
with (SG-)DMA API.  This leaded to a false-positive warning and the
driver failed to work.

Actually uaudio_transfer_buffer_setup() deals only with the DMA-API
addresses for MEM_XFER_BUF type, while other callers of
uaudio_iommu_map() are with pages with physical addresses for
MEM_EVENT_RING and MEM_XFER_RING types.  So this patch splits the
mapping helper function to two different ones, uaudio_iommu_map() for
the DMA pages and uaudio_iommu_map_pa() for the latter, in order to
handle mapping differently for each type.  Along with it, the
unnecessary address check that caused probe error is dropped, too.

Fixes: 3335a1bbd624 ("ALSA: qc_audio_offload: try to reduce address space confusion")
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reported-and-tested-by: Luca Weiss <luca.weiss@fairphone.com>
Closes: https://lore.kernel.org/DBR2363A95M1.L9XBNC003490@fairphone.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/qcom/qc_audio_offload.c b/sound/usb/qcom/qc_audio_offload.c
index a25c5a5316901cbfa8d9c1dae369cacd7581d41e..9ad76fff741b8de7ac857b7e0b555ce46dbf5e3f 100644 (file)
--- a/sound/usb/qcom/qc_audio_offload.c
+++ b/sound/usb/qcom/qc_audio_offload.c
@@ -538,38 +538,33 @@ static void uaudio_iommu_unmap(enum mem_type mtype, unsigned long iova,
                        umap_size, iova, mapped_iova_size);
 }
 
+static int uaudio_iommu_map_prot(bool dma_coherent)
+{
+       int prot = IOMMU_READ | IOMMU_WRITE;
+
+       if (dma_coherent)
+               prot |= IOMMU_CACHE;
+       return prot;
+}
+
 /**
- * uaudio_iommu_map() - maps iommu memory for adsp
+ * uaudio_iommu_map_pa() - maps iommu memory for adsp
  * @mtype: ring type
  * @dma_coherent: dma coherent
  * @pa: physical address for ring/buffer
  * @size: size of memory region
- * @sgt: sg table for memory region
  *
  * Maps the XHCI related resources to a memory region that is assigned to be
  * used by the adsp.  This will be mapped to the domain, which is created by
  * the ASoC USB backend driver.
  *
  */
-static unsigned long uaudio_iommu_map(enum mem_type mtype, bool dma_coherent,
-                                     phys_addr_t pa, size_t size,
-                                     struct sg_table *sgt)
+static unsigned long uaudio_iommu_map_pa(enum mem_type mtype, bool dma_coherent,
+                                        phys_addr_t pa, size_t size)
 {
-       struct scatterlist *sg;
        unsigned long iova = 0;
-       size_t total_len = 0;
-       unsigned long iova_sg;
-       phys_addr_t pa_sg;
        bool map = true;
-       size_t sg_len;
-       int prot;
-       int ret;
-       int i;
-
-       prot = IOMMU_READ | IOMMU_WRITE;
-
-       if (dma_coherent)
-               prot |= IOMMU_CACHE;
+       int prot = uaudio_iommu_map_prot(dma_coherent);
 
        switch (mtype) {
        case MEM_EVENT_RING:
@@ -583,20 +578,41 @@ static unsigned long uaudio_iommu_map(enum mem_type mtype, bool dma_coherent,
                                     &uaudio_qdev->xfer_ring_iova_size,
                                     &uaudio_qdev->xfer_ring_list, size);
                break;
-       case MEM_XFER_BUF:
-               iova = uaudio_get_iova(&uaudio_qdev->curr_xfer_buf_iova,
-                                    &uaudio_qdev->xfer_buf_iova_size,
-                                    &uaudio_qdev->xfer_buf_list, size);
-               break;
        default:
                dev_err(uaudio_qdev->data->dev, "unknown mem type %d\n", mtype);
        }
 
        if (!iova || !map)
-               goto done;
+               return 0;
+
+       iommu_map(uaudio_qdev->data->domain, iova, pa, size, prot, GFP_KERNEL);
 
-       if (!sgt)
-               goto skip_sgt_map;
+       return iova;
+}
+
+static unsigned long uaudio_iommu_map_xfer_buf(bool dma_coherent, size_t size,
+                                              struct sg_table *sgt)
+{
+       struct scatterlist *sg;
+       unsigned long iova = 0;
+       size_t total_len = 0;
+       unsigned long iova_sg;
+       phys_addr_t pa_sg;
+       size_t sg_len;
+       int prot = uaudio_iommu_map_prot(dma_coherent);
+       int ret;
+       int i;
+
+       prot = IOMMU_READ | IOMMU_WRITE;
+
+       if (dma_coherent)
+               prot |= IOMMU_CACHE;
+
+       iova = uaudio_get_iova(&uaudio_qdev->curr_xfer_buf_iova,
+                              &uaudio_qdev->xfer_buf_iova_size,
+                              &uaudio_qdev->xfer_buf_list, size);
+       if (!iova)
+               goto done;
 
        iova_sg = iova;
        for_each_sg(sgt->sgl, sg, sgt->nents, i) {
@@ -618,11 +634,6 @@ static unsigned long uaudio_iommu_map(enum mem_type mtype, bool dma_coherent,
                uaudio_iommu_unmap(MEM_XFER_BUF, iova, size, total_len);
                iova = 0;
        }
-       return iova;
-
-skip_sgt_map:
-       iommu_map(uaudio_qdev->data->domain, iova, pa, size, prot, GFP_KERNEL);
-
 done:
        return iova;
 }
@@ -1020,7 +1031,6 @@ static int uaudio_transfer_buffer_setup(struct snd_usb_substream *subs,
        struct sg_table xfer_buf_sgt;
        dma_addr_t xfer_buf_dma;
        void *xfer_buf;
-       phys_addr_t xfer_buf_pa;
        u32 len = xfer_buf_len;
        bool dma_coherent;
        dma_addr_t xfer_buf_dma_sysdev;
@@ -1051,18 +1061,12 @@ static int uaudio_transfer_buffer_setup(struct snd_usb_substream *subs,
        if (!xfer_buf)
                return -ENOMEM;
 
-       /* Remapping is not possible if xfer_buf is outside of linear map */
-       xfer_buf_pa = virt_to_phys(xfer_buf);
-       if (WARN_ON(!page_is_ram(PFN_DOWN(xfer_buf_pa)))) {
-               ret = -ENXIO;
-               goto unmap_sync;
-       }
        dma_get_sgtable(subs->dev->bus->sysdev, &xfer_buf_sgt, xfer_buf,
                        xfer_buf_dma, len);
 
        /* map the physical buffer into sysdev as well */
-       xfer_buf_dma_sysdev = uaudio_iommu_map(MEM_XFER_BUF, dma_coherent,
-                                              xfer_buf_pa, len, &xfer_buf_sgt);
+       xfer_buf_dma_sysdev = uaudio_iommu_map_xfer_buf(dma_coherent,
+                                                       len, &xfer_buf_sgt);
        if (!xfer_buf_dma_sysdev) {
                ret = -ENOMEM;
                goto unmap_sync;
@@ -1143,8 +1147,8 @@ uaudio_endpoint_setup(struct snd_usb_substream *subs,
        sg_free_table(sgt);
 
        /* data transfer ring */
-       iova = uaudio_iommu_map(MEM_XFER_RING, dma_coherent, tr_pa,
-                             PAGE_SIZE, NULL);
+       iova = uaudio_iommu_map_pa(MEM_XFER_RING, dma_coherent, tr_pa,
+                                  PAGE_SIZE);
        if (!iova) {
                ret = -ENOMEM;
                goto clear_pa;
@@ -1207,8 +1211,8 @@ static int uaudio_event_ring_setup(struct snd_usb_substream *subs,
        mem_info->dma = sg_dma_address(sgt->sgl);
        sg_free_table(sgt);
 
-       iova = uaudio_iommu_map(MEM_EVENT_RING, dma_coherent, er_pa,
-                             PAGE_SIZE, NULL);
+       iova = uaudio_iommu_map_pa(MEM_EVENT_RING, dma_coherent, er_pa,
+                                  PAGE_SIZE);
        if (!iova) {
                ret = -ENOMEM;
                goto clear_pa;