intel_th: msu: Fix single mode with disabled IOMMU

commit 918b8646497b5dba6ae82d4a7325f01b258972b9 upstream.

Commit 4e0eaf239fb3 ("intel_th: msu: Fix single mode with IOMMU") switched
the single mode code to use dma mapping pages obtained from the page
allocator, but with IOMMU disabled, that may lead to using SWIOTLB bounce
buffers and without additional sync'ing, produces empty trace buffers.

Fix this by using a DMA32 GFP flag to the page allocation in single mode,
as the device supports full 32-bit DMA addressing.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Fixes: 4e0eaf239fb3 ("intel_th: msu: Fix single mode with IOMMU")
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reported-by: Ammy Yi <ammy.yi@intel.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20190621161930.60785-4-alexander.shishkin@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hwtracing/intel_th/msu.c b/drivers/hwtracing/intel_th/msu.c
index 36016c09dd964ed18a84990674db24948a97901a..6ebf6a2edb3325bbee48bd0c6e4a29c83600514e 100644 (file)
--- a/drivers/hwtracing/intel_th/msu.c
+++ b/drivers/hwtracing/intel_th/msu.c
@@ -640,7 +640,7 @@ static int msc_buffer_contig_alloc(struct msc *msc, unsigned long size)
                goto err_out;
 
        ret = -ENOMEM;
-       page = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
+       page = alloc_pages(GFP_KERNEL | __GFP_ZERO | GFP_DMA32, order);
        if (!page)
                goto err_free_sgt;