intel_th: msu: Fix single mode with IOMMU

BugLink: https://bugs.launchpad.net/bugs/1832661

commit 4e0eaf23 upstream.

Currently, the pages that are allocated for the single mode of MSC are not
mapped into the device's dma space and the code is incorrectly using
*_to_phys() in place of a dma address. This fails with IOMMU enabled and
is otherwise bad practice.

Fix the single mode buffer allocation to map the pages into the device's
DMA space.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Fixes: ba82664c ("intel_th: Add Memory Storage Unit driver")
Cc: stable@vger.kernel.org # v4.4+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/hwtracing/intel_th/msu.c

@@ -90,6 +90,7 @@ struct msc_iter {
  * @reg_base:		register window base address
  * @thdev:		intel_th_device pointer
  * @win_list:		list of windows in multiblock mode
+ * @single_sgt:		single mode buffer
  * @nr_pages:		total number of pages allocated for this buffer
  * @single_sz:		amount of data in single mode
  * @single_wrap:	single mode wrap occurred
@@ -110,6 +111,7 @@ struct msc {
 	struct intel_th_device	*thdev;
 
 	struct list_head	win_list;
+	struct sg_table		single_sgt;
 	unsigned long		nr_pages;
 	unsigned long		single_sz;
 	unsigned int		single_wrap : 1;
@@ -610,22 +612,45 @@ static void intel_th_msc_deactivate(struct intel_th_device *thdev)
  */
 static int msc_buffer_contig_alloc(struct msc *msc, unsigned long size)
 {
+	unsigned long nr_pages = size >> PAGE_SHIFT;
 	unsigned int order = get_order(size);
 	struct page *page;
+	int ret;
 
 	if (!size)
 		return 0;
 
+	ret = sg_alloc_table(&msc->single_sgt, 1, GFP_KERNEL);
+	if (ret)
+		goto err_out;
+
+	ret = -ENOMEM;
 	page = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
 	if (!page)
-		return -ENOMEM;
+		goto err_free_sgt;
 
 	split_page(page, order);
-	msc->nr_pages = size >> PAGE_SHIFT;
+	sg_set_buf(msc->single_sgt.sgl, page_address(page), size);
+
+	ret = dma_map_sg(msc_dev(msc)->parent->parent, msc->single_sgt.sgl, 1,
+			 DMA_FROM_DEVICE);
+	if (ret < 0)
+		goto err_free_pages;
+
+	msc->nr_pages = nr_pages;
 	msc->base = page_address(page);
-	msc->base_addr = page_to_phys(page);
+	msc->base_addr = sg_dma_address(msc->single_sgt.sgl);
 
 	return 0;
+
+err_free_pages:
+	__free_pages(page, order);
+
+err_free_sgt:
+	sg_free_table(&msc->single_sgt);
+
+err_out:
+	return ret;
 }
 
 /**
@@ -636,6 +661,10 @@ static void msc_buffer_contig_free(struct msc *msc)
 {
 	unsigned long off;
 
+	dma_unmap_sg(msc_dev(msc)->parent->parent, msc->single_sgt.sgl,
+		     1, DMA_FROM_DEVICE);
+	sg_free_table(&msc->single_sgt);
+
 	for (off = 0; off < msc->nr_pages << PAGE_SHIFT; off += PAGE_SIZE) {
 		struct page *page = virt_to_page(msc->base + off);