From: Lu Baolu <baolu.lu@linux.intel.com> To: Jason Gunthorpe <jgg@nvidia.com> Cc: baolu.lu@linux.intel.com, Joerg Roedel <joro@8bytes.org>, Christoph Hellwig <hch@infradead.org>, Kevin Tian <kevin.tian@intel.com>, Ashok Raj <ashok.raj@intel.com>, Will Deacon <will@kernel.org>, Robin Murphy <robin.murphy@arm.com>, Jean-Philippe Brucker <jean-philippe@linaro.com>, Eric Auger <eric.auger@redhat.com>, Liu Yi L <yi.l.liu@intel.com>, Jacob jun Pan <jacob.jun.pan@intel.com>, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC 10/11] iommu: Make IOPF handling framework generic Date: Tue, 22 Mar 2022 13:48:49 +0800 [thread overview] Message-ID: <45860360-4648-3f0b-6758-fe398aca4204@linux.intel.com> (raw) In-Reply-To: <20220321125021.GQ11336@nvidia.com> On 2022/3/21 20:50, Jason Gunthorpe wrote: > On Sun, Mar 20, 2022 at 02:40:29PM +0800, Lu Baolu wrote: > >> +static enum iommu_page_response_code >> +iommu_sva_handle_iopf(struct iommu_fault *fault, void *data) >> +{ >> + vm_fault_t ret; >> + struct mm_struct *mm; >> + struct vm_area_struct *vma; >> + unsigned int access_flags = 0; >> + struct iommu_domain *domain = data; > > Why is the iommu_domain not passed in as a fully typed object? I would > think data should some opaque value used by non-sva cases. The "data" is set together with the fault handler when the caller installs a fault handler for an iommu domain. We will add a generic interface to install fault handler for an iommu domain later when a real non-sva case comes. > > What is the lifetime model here anyhow? I simply thought that the device driver should guarantee that there are no pending faults after sva_unbind(). This is insufficient. I need to rework this. > >> + unsigned int fault_flags = FAULT_FLAG_REMOTE; >> + struct iommu_fault_page_request *prm = &fault->prm; >> + enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID; >> + >> + if (!(prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID)) >> + return status; >> + >> + mm = domain->sva_cookie; >> + if (IS_ERR_OR_NULL(mm)) > > Do not use this function > > Do not store err pointers in structs. Sure. > >> +out_put_mm: >> + mmap_read_unlock(mm); >> + mmput(mm); > > mm structs are weird, they have two refcounts. > > The 'sva_cookie' should hold a mmgrab/mmdrop() refcount to keep the > pointer alive but to touch the mmap lock you have to upgrade it to a > refcount that prevents destruction using mmget_not_zero() just for > this short period. Yes. Will look into it. Best regards, baolu
WARNING: multiple messages have this Message-ID (diff)
From: Lu Baolu <baolu.lu@linux.intel.com> To: Jason Gunthorpe <jgg@nvidia.com> Cc: Kevin Tian <kevin.tian@intel.com>, Ashok Raj <ashok.raj@intel.com>, Robin Murphy <robin.murphy@arm.com>, linux-kernel@vger.kernel.org, Christoph Hellwig <hch@infradead.org>, Jean-Philippe Brucker <jean-philippe@linaro.com>, iommu@lists.linux-foundation.org, Jacob jun Pan <jacob.jun.pan@intel.com>, Will Deacon <will@kernel.org> Subject: Re: [PATCH RFC 10/11] iommu: Make IOPF handling framework generic Date: Tue, 22 Mar 2022 13:48:49 +0800 [thread overview] Message-ID: <45860360-4648-3f0b-6758-fe398aca4204@linux.intel.com> (raw) In-Reply-To: <20220321125021.GQ11336@nvidia.com> On 2022/3/21 20:50, Jason Gunthorpe wrote: > On Sun, Mar 20, 2022 at 02:40:29PM +0800, Lu Baolu wrote: > >> +static enum iommu_page_response_code >> +iommu_sva_handle_iopf(struct iommu_fault *fault, void *data) >> +{ >> + vm_fault_t ret; >> + struct mm_struct *mm; >> + struct vm_area_struct *vma; >> + unsigned int access_flags = 0; >> + struct iommu_domain *domain = data; > > Why is the iommu_domain not passed in as a fully typed object? I would > think data should some opaque value used by non-sva cases. The "data" is set together with the fault handler when the caller installs a fault handler for an iommu domain. We will add a generic interface to install fault handler for an iommu domain later when a real non-sva case comes. > > What is the lifetime model here anyhow? I simply thought that the device driver should guarantee that there are no pending faults after sva_unbind(). This is insufficient. I need to rework this. > >> + unsigned int fault_flags = FAULT_FLAG_REMOTE; >> + struct iommu_fault_page_request *prm = &fault->prm; >> + enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID; >> + >> + if (!(prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID)) >> + return status; >> + >> + mm = domain->sva_cookie; >> + if (IS_ERR_OR_NULL(mm)) > > Do not use this function > > Do not store err pointers in structs. Sure. > >> +out_put_mm: >> + mmap_read_unlock(mm); >> + mmput(mm); > > mm structs are weird, they have two refcounts. > > The 'sva_cookie' should hold a mmgrab/mmdrop() refcount to keep the > pointer alive but to touch the mmap lock you have to upgrade it to a > refcount that prevents destruction using mmget_not_zero() just for > this short period. Yes. Will look into it. Best regards, baolu _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2022-03-22 5:49 UTC|newest] Thread overview: 112+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-03-20 6:40 [PATCH RFC 00/11] iommu: SVA and IOPF refactoring Lu Baolu 2022-03-20 6:40 ` Lu Baolu 2022-03-20 6:40 ` [PATCH RFC 01/11] iommu: Add pasid_bits field in struct dev_iommu Lu Baolu 2022-03-20 6:40 ` Lu Baolu 2022-03-21 7:01 ` Tian, Kevin 2022-03-21 7:01 ` Tian, Kevin 2022-03-21 10:22 ` Lu Baolu 2022-03-21 10:22 ` Lu Baolu 2022-03-22 0:26 ` Tian, Kevin 2022-03-22 0:26 ` Tian, Kevin 2022-03-22 0:48 ` Lu Baolu 2022-03-22 0:48 ` Lu Baolu 2022-03-21 11:22 ` Jean-Philippe Brucker 2022-03-21 11:22 ` Jean-Philippe Brucker 2022-03-22 0:45 ` Lu Baolu 2022-03-22 0:45 ` Lu Baolu 2022-03-20 6:40 ` [PATCH RFC 02/11] iommu: Add iommu_domain type for SVA Lu Baolu 2022-03-20 6:40 ` Lu Baolu 2022-03-21 7:06 ` Tian, Kevin 2022-03-21 7:06 ` Tian, Kevin 2022-03-21 10:23 ` Lu Baolu 2022-03-21 10:23 ` Lu Baolu 2022-03-21 11:47 ` Jason Gunthorpe 2022-03-21 11:47 ` Jason Gunthorpe via iommu 2022-03-22 0:54 ` Lu Baolu 2022-03-22 0:54 ` Lu Baolu 2022-03-20 6:40 ` [PATCH RFC 03/11] iommu: Add attach/detach_dev_pasid domain ops Lu Baolu 2022-03-20 6:40 ` Lu Baolu 2022-03-21 7:13 ` Tian, Kevin 2022-03-21 7:13 ` Tian, Kevin 2022-03-21 10:27 ` Lu Baolu 2022-03-21 10:27 ` Lu Baolu 2022-03-21 11:53 ` Jason Gunthorpe via iommu 2022-03-21 11:53 ` Jason Gunthorpe 2022-03-20 6:40 ` [PATCH RFC 04/11] iommu/vt-d: Add SVA domain support Lu Baolu 2022-03-20 6:40 ` Lu Baolu 2022-03-21 7:45 ` Tian, Kevin 2022-03-21 7:45 ` Tian, Kevin 2022-03-21 10:37 ` Lu Baolu 2022-03-21 10:37 ` Lu Baolu 2022-03-21 11:56 ` Jason Gunthorpe via iommu 2022-03-21 11:56 ` Jason Gunthorpe 2022-03-22 4:25 ` Lu Baolu 2022-03-22 4:25 ` Lu Baolu 2022-03-20 6:40 ` [PATCH RFC 05/11] arm-smmu-v3/sva: " Lu Baolu 2022-03-20 6:40 ` Lu Baolu 2022-03-21 11:31 ` Jean-Philippe Brucker 2022-03-21 11:31 ` Jean-Philippe Brucker 2022-03-21 11:58 ` Jason Gunthorpe 2022-03-21 11:58 ` Jason Gunthorpe via iommu 2022-03-20 6:40 ` [PATCH RFC 06/11] iommu/sva: Use attach/detach_pasid_dev in SVA interfaces Lu Baolu 2022-03-20 6:40 ` Lu Baolu 2022-03-21 8:04 ` Tian, Kevin 2022-03-21 8:04 ` Tian, Kevin 2022-03-21 11:01 ` Lu Baolu 2022-03-21 11:01 ` Lu Baolu 2022-03-21 12:03 ` Jason Gunthorpe 2022-03-21 12:03 ` Jason Gunthorpe via iommu 2022-03-21 11:33 ` Jean-Philippe Brucker 2022-03-21 11:33 ` Jean-Philippe Brucker 2022-03-22 4:29 ` Lu Baolu 2022-03-22 4:29 ` Lu Baolu 2022-03-21 12:05 ` Jason Gunthorpe 2022-03-21 12:05 ` Jason Gunthorpe via iommu 2022-03-22 4:31 ` Lu Baolu 2022-03-22 4:31 ` Lu Baolu 2022-03-20 6:40 ` [PATCH RFC 07/11] iommu: Remove SVA related callbacks from iommu ops Lu Baolu 2022-03-20 6:40 ` Lu Baolu 2022-03-20 6:40 ` [PATCH RFC 08/11] iommu: Handle IO page faults directly Lu Baolu 2022-03-20 6:40 ` Lu Baolu 2022-03-21 11:35 ` Jean-Philippe Brucker 2022-03-21 11:35 ` Jean-Philippe Brucker 2022-03-22 0:39 ` Tian, Kevin 2022-03-22 0:39 ` Tian, Kevin 2022-03-20 6:40 ` [PATCH RFC 09/11] iommu: Add iommu_get_domain_for_dev_pasid() Lu Baolu 2022-03-20 6:40 ` Lu Baolu 2022-03-21 12:40 ` Jason Gunthorpe 2022-03-21 12:40 ` Jason Gunthorpe via iommu 2022-03-22 4:50 ` Lu Baolu 2022-03-22 4:50 ` Lu Baolu 2022-03-20 6:40 ` [PATCH RFC 10/11] iommu: Make IOPF handling framework generic Lu Baolu 2022-03-20 6:40 ` Lu Baolu 2022-03-21 8:09 ` Tian, Kevin 2022-03-21 8:09 ` Tian, Kevin 2022-03-21 11:42 ` Jean-Philippe Brucker 2022-03-21 11:42 ` Jean-Philippe Brucker 2022-03-21 12:43 ` Jason Gunthorpe 2022-03-21 12:43 ` Jason Gunthorpe via iommu 2022-03-22 5:03 ` Lu Baolu 2022-03-22 5:03 ` Lu Baolu 2022-03-22 10:02 ` Jean-Philippe Brucker 2022-03-22 10:02 ` Jean-Philippe Brucker 2022-03-22 12:15 ` Jason Gunthorpe 2022-03-22 12:15 ` Jason Gunthorpe via iommu 2022-03-22 1:00 ` Tian, Kevin 2022-03-22 1:00 ` Tian, Kevin 2022-03-22 10:06 ` Jean-Philippe Brucker 2022-03-22 10:06 ` Jean-Philippe Brucker 2022-03-22 10:24 ` Tian, Kevin 2022-03-22 10:24 ` Tian, Kevin 2022-03-22 10:50 ` Jean-Philippe Brucker 2022-03-22 10:50 ` Jean-Philippe Brucker 2022-03-21 11:39 ` Jean-Philippe Brucker 2022-03-21 11:39 ` Jean-Philippe Brucker 2022-03-22 5:28 ` Lu Baolu 2022-03-22 5:28 ` Lu Baolu 2022-03-21 12:50 ` Jason Gunthorpe 2022-03-21 12:50 ` Jason Gunthorpe via iommu 2022-03-22 5:48 ` Lu Baolu [this message] 2022-03-22 5:48 ` Lu Baolu 2022-03-20 6:40 ` [PATCH RFC 11/11] iommu: Rename iommu-sva-lib.{c,h} Lu Baolu 2022-03-20 6:40 ` Lu Baolu
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