From mboxrd@z Thu Jan 1 00:00:00 1970 From: Antonios Motakis Subject: Re: [RFC PATCH v5 02/11] ARM SMMU: Add capability IOMMU_CAP_DMA_EXEC Date: Tue, 29 Apr 2014 11:49:48 +0200 Message-ID: References: <1398700371-20096-1-git-send-email-a.motakis@virtualopensystems.com> <1398700371-20096-3-git-send-email-a.motakis@virtualopensystems.com> <20140428193709.GE22135@arm.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============6343610371212242751==" Return-path: In-Reply-To: <20140428193709.GE22135-5wv7dgnIgG8@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Will Deacon Cc: Shuah Khan , "stuart.yoder-KZfg59tc24xl57MIdRCFDg@public.gmane.org" , "kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Alexey Kardashevskiy , open list , "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" , "a.rigo-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org" , "moderated list:ARM SMMU DRIVER" , Varun Sethi , "tech-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org" , "kvmarm-FPEHb7Xf0XXUo1n7N8X6UoWGPAHP3yOg@public.gmane.org" , "christoffer.dall-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" List-Id: iommu@lists.linux-foundation.org --===============6343610371212242751== Content-Type: multipart/alternative; boundary=047d7b15a16d7fa0e104f82b5bde --047d7b15a16d7fa0e104f82b5bde Content-Type: text/plain; charset=ISO-8859-1 I agree, that would be simpler for the user. As it is now we have to worry about whether the EXEC flac is available just to use the PL330, with NOEXEC the device would always be usable by default. On Mon, Apr 28, 2014 at 9:37 PM, Will Deacon wrote: > On Mon, Apr 28, 2014 at 04:52:42PM +0100, Antonios Motakis wrote: > > The ARM SMMU can take an IOMMU_EXEC protection flag in addition to > > IOMMU_READ and IOMMU_WRITE. Expose this as an IOMMU capability. > > The other way of handling this would be to negate the capability and > advertise a NOEXEC cap instead. That would need the IOMMU_EXEC flag to > become IOMMU_NOEXEC and the ARM SMMU driver updating accordingly, but it > might make more sense if people don't object to mixing positive and > negative > logic in the IOMMU_* flags. > > Any thoughts? > > Will > -- Antonios Motakis Virtual Open Systems --047d7b15a16d7fa0e104f82b5bde Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
I agree, that would be simpler for the user. As it is now = we have to worry about whether the EXEC flac is available just to use the P= L330, with NOEXEC the device would always be usable by default.


On Mon, Apr 28, 2014 at 9:37 PM, Will De= acon <will.deacon-5wv7dgnIgG8@public.gmane.org> wrote:
On Mon, Apr 28, 2014 at 04:52:42PM +0100, Antonios Motakis = wrote:
> The ARM SMMU can take an IOMMU_EXEC protection flag in addition to
> IOMMU_READ and IOMMU_WRITE. Expose this as an IOMMU capability.

The other way of handling this would be to negate the capability and<= br> advertise a NOEXEC cap instead. That would need the IOMMU_EXEC flag to
become IOMMU_NOEXEC and the ARM SMMU driver updating accordingly, but it might make more sense if people don't object to mixing positive and neg= ative
logic in the IOMMU_* flags.

Any thoughts?

Will



--
Antonios = Motakis
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