[PATCH] iommu/arm-smmu-v3: avoid over allocating for l2 stream tables
Will Deacon
will.deacon at arm.com
Tue Dec 20 02:22:09 PST 2016
Hi Nate,
On Mon, Dec 19, 2016 at 03:26:40PM -0500, Nate Watterson wrote:
> Currently, all l2 stream tables are being allocated with space for
> (1<<split) stes without regard to the number of sid bits the smmu
> physically supports. To avoid allocating memory for inaccessible
> stes, this patch limits the span of an l2 table to be no larger
> than the sid size of the smmu to which it belongs.
>
> Signed-off-by: Nate Watterson <nwatters at codeaurora.org>
> ---
> drivers/iommu/arm-smmu-v3.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
I can't help but think you'd be better off using a linear stream table
in this scenario. If we hack the feature check for
ARM_SMMU_FEAT_2_LVL_STRTAB so that it doesn't report support for 2 level
tables if the number of sids is less than that covered by a single l2
entry, would that solve your problem?
Will
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