NTB: transport: Try harder to alloc an aligned MW buffer

Be a little wasteful if the (likely CMA) message window buffer is not
suitably aligned after our first attempt; allocate a buffer twice as big
as we need and manually align our MW buffer within it.

This was needed on Intel Broadwell DE platforms with intel_iommu=off

Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
index c643b9cf750bd77cdb569832641a095c5d9cf249..3bfdb4562408879fd04f340b05e84673c4da2232 100644 (file)
--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c
@@ -194,6 +194,8 @@ struct ntb_transport_mw {
        void __iomem *vbase;
        size_t xlat_size;
        size_t buff_size;
+       size_t alloc_size;
+       void *alloc_addr;
        void *virt_addr;
        dma_addr_t dma_addr;
 };
@@ -672,13 +674,59 @@ static void ntb_free_mw(struct ntb_transport_ctx *nt, int num_mw)
                return;
 
        ntb_mw_clear_trans(nt->ndev, PIDX, num_mw);
-       dma_free_coherent(&pdev->dev, mw->buff_size,
-                         mw->virt_addr, mw->dma_addr);
+       dma_free_coherent(&pdev->dev, mw->alloc_size,
+                         mw->alloc_addr, mw->dma_addr);
        mw->xlat_size = 0;
        mw->buff_size = 0;
+       mw->alloc_size = 0;
+       mw->alloc_addr = NULL;
        mw->virt_addr = NULL;
 }
 
+static int ntb_alloc_mw_buffer(struct ntb_transport_mw *mw,
+                              struct device *dma_dev, size_t align)
+{
+       dma_addr_t dma_addr;
+       void *alloc_addr, *virt_addr;
+       int rc;
+
+       alloc_addr = dma_alloc_coherent(dma_dev, mw->alloc_size,
+                                       &dma_addr, GFP_KERNEL);
+       if (!alloc_addr) {
+               dev_err(dma_dev, "Unable to alloc MW buff of size %zu\n",
+                       mw->alloc_size);
+               return -ENOMEM;
+       }
+       virt_addr = alloc_addr;
+
+       /*
+        * we must ensure that the memory address allocated is BAR size
+        * aligned in order for the XLAT register to take the value. This
+        * is a requirement of the hardware. It is recommended to setup CMA
+        * for BAR sizes equal or greater than 4MB.
+        */
+       if (!IS_ALIGNED(dma_addr, align)) {
+               if (mw->alloc_size > mw->buff_size) {
+                       virt_addr = PTR_ALIGN(alloc_addr, align);
+                       dma_addr = ALIGN(dma_addr, align);
+               } else {
+                       rc = -ENOMEM;
+                       goto err;
+               }
+       }
+
+       mw->alloc_addr = alloc_addr;
+       mw->virt_addr = virt_addr;
+       mw->dma_addr = dma_addr;
+
+       return 0;
+
+err:
+       dma_free_coherent(dma_dev, mw->alloc_size, alloc_addr, dma_addr);
+
+       return rc;
+}
+
 static int ntb_set_mw(struct ntb_transport_ctx *nt, int num_mw,
                      resource_size_t size)
 {
@@ -710,28 +758,20 @@ static int ntb_set_mw(struct ntb_transport_ctx *nt, int num_mw,
        /* Alloc memory for receiving data.  Must be aligned */
        mw->xlat_size = xlat_size;
        mw->buff_size = buff_size;
+       mw->alloc_size = buff_size;
 
-       mw->virt_addr = dma_alloc_coherent(&pdev->dev, buff_size,
-                                          &mw->dma_addr, GFP_KERNEL);
-       if (!mw->virt_addr) {
-               mw->xlat_size = 0;
-               mw->buff_size = 0;
-               dev_err(&pdev->dev, "Unable to alloc MW buff of size %zu\n",
-                       buff_size);
-               return -ENOMEM;
-       }
-
-       /*
-        * we must ensure that the memory address allocated is BAR size
-        * aligned in order for the XLAT register to take the value. This
-        * is a requirement of the hardware. It is recommended to setup CMA
-        * for BAR sizes equal or greater than 4MB.
-        */
-       if (!IS_ALIGNED(mw->dma_addr, xlat_align)) {
-               dev_err(&pdev->dev, "DMA memory %pad is not aligned\n",
-                       &mw->dma_addr);
-               ntb_free_mw(nt, num_mw);
-               return -ENOMEM;
+       rc = ntb_alloc_mw_buffer(mw, &pdev->dev, xlat_align);
+       if (rc) {
+               mw->alloc_size *= 2;
+               rc = ntb_alloc_mw_buffer(mw, &pdev->dev, xlat_align);
+               if (rc) {
+                       dev_err(&pdev->dev,
+                               "Unable to alloc aligned MW buff\n");
+                       mw->xlat_size = 0;
+                       mw->buff_size = 0;
+                       mw->alloc_size = 0;
+                       return rc;
+               }
        }
 
        /* Notify HW the memory location of the receive buffer */