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Commit a9ed40b1 authored by Mitchel Humpherys's avatar Mitchel Humpherys
Browse files

iommu: msm_iommu_sec: fix some overeager cache maintenance 



In general, we must do some cache maintenance when sharing buffers with
TZ since our caches are not shared with TZ.  Specifically:

    (1) If we put some data into a buffer then share it with TZ for
        reading, the buffer must be flushed before sending it to TZ.

    (2) If TZ puts some data in a buffer for us to read, the buffer must
        be invalidated after receiving it from TZ.

In msm_iommu_sec_ptbl_map we are currently doing some cache maintenance
incorrectly.  We are invalidating a buffer that we shared with TZ even
though we're not reading from the buffer.  We're also flushing way more
than we need to.  We're only sharing a single buffer of size
sizeof(phys_addr_t) with TZ but we're flushing the size of the IOMMU
mapping (which could be anything up to 2^sizeof(size_t)).

Remove the unnecessary invalidate and only flush the size of the buffer
being shared, nothing more.

Change-Id: I46d2d95319364d197ae530001851ab819a6eb6fa
Signed-off-by: default avatarMitchel Humpherys <mitchelh@codeaurora.org>
parent cb0b4937

drivers/iommu/msm_iommu_sec.c

+5 −9
Original line number Diff line number Diff line
@@ -511,8 +511,7 @@ static int msm_iommu_sec_ptbl_map(struct msm_iommu_drvdata *iommu_drvdata, 
			unsigned long va, phys_addr_t pa, size_t len)

{

	struct msm_scm_map2_req map;

	void *flush_va;

	phys_addr_t flush_pa;

	void *flush_va, *flush_va_end;

	int ret = 0;



	map.plist.list = virt_to_phys(&pa);
@@ -524,20 +523,18 @@ static int msm_iommu_sec_ptbl_map(struct msm_iommu_drvdata *iommu_drvdata, 
	map.info.size = len;



	flush_va = &pa;

	flush_pa = virt_to_phys(&pa);

	flush_va_end = (void *)

		(((unsigned long) flush_va) + sizeof(phys_addr_t));



	/*

	 * Ensure that the buffer is in RAM by the time it gets to TZ

	 */

	dmac_clean_range(flush_va, flush_va + len);

	dmac_clean_range(flush_va, flush_va_end);



	ret = msm_iommu_sec_map2(&map);

	if (ret)

		return -EINVAL;



	/* Invalidate cache since TZ touched this address range */

	dmac_inv_range(flush_va, flush_va + len);



	return 0;

}
@@ -616,8 +613,7 @@ static int msm_iommu_sec_ptbl_map_range(struct msm_iommu_drvdata *iommu_drvdata, 
	/*

	 * Ensure that the buffer is in RAM by the time it gets to TZ

	 */

	dmac_clean_range(flush_va,

		flush_va + sizeof(unsigned long) * map.plist.list_size);

	dmac_clean_range(flush_va, flush_va + map.plist.list_size);



	ret = msm_iommu_sec_map2(&map);

	kfree(pa_list);