From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Tue, 20 Dec 2016 10:22:09 +0000 Subject: [PATCH] iommu/arm-smmu-v3: avoid over allocating for l2 stream tables In-Reply-To: <1482179200-4264-1-git-send-email-nwatters@codeaurora.org> References: <1482179200-4264-1-git-send-email-nwatters@codeaurora.org> Message-ID: <20161220102209.GC10132@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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< 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 > --- > 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