linux-kernel - [PATCH v5 13/13] swiotlb: don't assume that io_tlb_start-io_tlb

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Message-ID: <1377801154-29215-13-git-send-email-stefano.stabellini@eu.citrix.com>
Date:	Thu, 29 Aug 2013 19:32:34 +0100
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	<xen-devel@...ts.xensource.com>
CC:	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <konrad.wilk@...cle.com>,
	<Stefano.Stabellini@...citrix.com>, <Ian.Campbell@...rix.com>,
	Stefano Stabellini <stefano.stabellini@...citrix.com>
Subject: [PATCH v5 13/13] swiotlb: don't assume that io_tlb_start-io_tlb_end is coherent

The swiotlb code has appropriate calls to dma_mark_clean in place for
buffers passed to swiotlb_map_page as an argument. However it assumes
that the swiotlb bounce buffer (io_tlb_start-io_tlb_end) is already
coherent and doesn't need any calls to dma_mark_clean.

On ARM the swiotlb bounce buffer is not coherent (the memory is
writealloc while it should be bufferable) and therefore we need to call
dma_mark_clean appropriately on the bounce buffer code paths too.

Note that most architecures have an empty dma_mark_clean implementation
anyway.

Signed-off-by: Stefano Stabellini <stefano.stabellini@...citrix.com>
---
 lib/swiotlb.c |   12 +++++++++---
 1 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 4e8686c..b1f43f6 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -547,7 +547,10 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
 	 * First, sync the memory before unmapping the entry
 	 */
 	if (orig_addr && ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
+	{
+		dma_mark_clean(phys_to_virt(tlb_addr), size);
 		swiotlb_bounce(orig_addr, tlb_addr, size, DMA_FROM_DEVICE);
+	}
 
 	/*
 	 * Return the buffer to the free list by setting the corresponding
@@ -587,17 +590,20 @@ void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr,
 
 	switch (target) {
 	case SYNC_FOR_CPU:
-		if (likely(dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL))
+		if (likely(dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL)) {
+			dma_mark_clean(phys_to_virt(tlb_addr), size);
 			swiotlb_bounce(orig_addr, tlb_addr,
 				       size, DMA_FROM_DEVICE);
+		}
 		else
 			BUG_ON(dir != DMA_TO_DEVICE);
 		break;
 	case SYNC_FOR_DEVICE:
-		if (likely(dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
+		if (likely(dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)) {
 			swiotlb_bounce(orig_addr, tlb_addr,
 				       size, DMA_TO_DEVICE);
-		else
+			dma_mark_clean(phys_to_virt(tlb_addr), size);
+		} else
 			BUG_ON(dir != DMA_FROM_DEVICE);
 		break;
 	default:
-- 
1.7.2.5

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