From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH 1/2] iommu: Support dynamic pgsize_bitmap Date: Thu, 7 Apr 2016 15:24:30 +0200 Message-ID: <20160407132430.GE31146@8bytes.org> References: <1459890090-16040-1-git-send-email-mitchelh@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1459890090-16040-1-git-send-email-mitchelh-sgV2jX0FEOL9JmXXK+q4OQ@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: Mitchel Humpherys Cc: Will Deacon , iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Pratik Patel List-Id: iommu@lists.linux-foundation.org On Tue, Apr 05, 2016 at 02:01:29PM -0700, Mitchel Humpherys wrote: > Currently we use a single pgsize_bitmap per IOMMU driver. However, some > IOMMU drivers might service different IOMMUs with different supported > page sizes. Some drivers might also want to restrict page sizes for > different use cases. Support these use cases by adding a > .get_pgsize_bitmap function to the iommu_ops which can optionally be > used by the driver to return a domain-specific pgsize_bitmap. No, at least not this way. I said it before and I say it again: We are not going to lift the iommu-api requirements in this undetectable way. The iommu-api works with domains/groups and devices. The general expectation is that every group can be part of every domain. I know that this is not the case already with some drivers, but I am not going to move the code further into the wrong direction. The way I'd like to see that solved is: * Introduce per-group pgsize-bitmaps (group->pgsize_bmp) * Calculate a global pgsize-bitmap from all groups pgsize-bitmaps * Also store a pgsize_bitmap in each domain on allocation * Modify iommu_domain_alloc to set domain->pgsize_bmp to the global pgsize_bitmap * Introduce an iommu_group_alloc_domain(group) function which allocates a new domain only for the given group. This function sets domain->pgsize_bitmap to group->pgsize_bmp. * Note that now you can have multiple page-tables per domain, one page-table for each required format. Regards, Joerg From mboxrd@z Thu Jan 1 00:00:00 1970 From: joro@8bytes.org (Joerg Roedel) Date: Thu, 7 Apr 2016 15:24:30 +0200 Subject: [PATCH 1/2] iommu: Support dynamic pgsize_bitmap In-Reply-To: <1459890090-16040-1-git-send-email-mitchelh@codeaurora.org> References: <1459890090-16040-1-git-send-email-mitchelh@codeaurora.org> Message-ID: <20160407132430.GE31146@8bytes.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Apr 05, 2016 at 02:01:29PM -0700, Mitchel Humpherys wrote: > Currently we use a single pgsize_bitmap per IOMMU driver. However, some > IOMMU drivers might service different IOMMUs with different supported > page sizes. Some drivers might also want to restrict page sizes for > different use cases. Support these use cases by adding a > .get_pgsize_bitmap function to the iommu_ops which can optionally be > used by the driver to return a domain-specific pgsize_bitmap. No, at least not this way. I said it before and I say it again: We are not going to lift the iommu-api requirements in this undetectable way. The iommu-api works with domains/groups and devices. The general expectation is that every group can be part of every domain. I know that this is not the case already with some drivers, but I am not going to move the code further into the wrong direction. The way I'd like to see that solved is: * Introduce per-group pgsize-bitmaps (group->pgsize_bmp) * Calculate a global pgsize-bitmap from all groups pgsize-bitmaps * Also store a pgsize_bitmap in each domain on allocation * Modify iommu_domain_alloc to set domain->pgsize_bmp to the global pgsize_bitmap * Introduce an iommu_group_alloc_domain(group) function which allocates a new domain only for the given group. This function sets domain->pgsize_bitmap to group->pgsize_bmp. * Note that now you can have multiple page-tables per domain, one page-table for each required format. Regards, Joerg