> -----Original Message----- > From: Mark Rutland [mailto:mark.rutland@xxxxxxx] > Sent: 27 January 2016 17:59 > To: Anup Patel > Cc: Catalin Marinas; Joerg Roedel; Will Deacon; Robin Murphy; Sricharan R; > Linux IOMMU; Linux ARM Kernel; Rob Herring; Pawel Moll; Ian Campbell; Kumar > Gala; Device Tree; Ray Jui; Scott Branden; Vikram Prakash; Linux Kernel; bcm- > kernel-feedback-list > Subject: Re: [RFC PATCH 6/6] iommu/arm-smmu: Update bindings document for > smmu-inst-as-data DT option > > On Wed, Jan 27, 2016 at 10:51:19AM +0530, Anup Patel wrote: > > This patch adds info about 'smmu-inst-as-data' DT option in ARM > > SMMUv1/SMMUv2 driver bindings document. > > > > Signed-off-by: Anup Patel <anup.patel@xxxxxxxxxxxx> > > Reviewed-by: Ray Jui <rjui@xxxxxxxxxxxx> > > Reviewed-by: Vikram Prakash <vikramp@xxxxxxxxxxxx> > > Reviewed-by: Scott Branden <sbranden@xxxxxxxxxxxx> > > --- > > Documentation/devicetree/bindings/iommu/arm,smmu.txt | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.txt > > b/Documentation/devicetree/bindings/iommu/arm,smmu.txt > > index 7180745..4c4d03e 100644 > > --- a/Documentation/devicetree/bindings/iommu/arm,smmu.txt > > +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.txt > > @@ -49,6 +49,14 @@ conditions. > > NOTE: this only applies to the SMMU itself, not > > masters connected upstream of the SMMU. > > > > +- smmu-inst-as-data : Treat privilege/unprivilege instruction fetch as > > + data read for SMMUv2. The SMMU driver by default provides > > + unprivilege read-write permission in page table entries. > > + For SMMUv2, privilege instruction fetch from MMU masters > > + will cause a context fault for unprivilege read-write > > + pages. To allow both privilege and unprivilege instruction > > + fetch, we have to forcefully treat it as data read. > > What is this needed for? Which masters do instruction fetches through the > SMMU, and when? > > Surely this should only need to aplly to a subset of transactions? The boot_manager of PL330 does privileged instruction fetches which cause privilege-level context fault in SMMU because current SMMU driver provides unprivileged read-write permissions. Regards, Anup -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
