From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean-Philippe Brucker Subject: Re: [RFC v3 14/21] iommu: introduce device fault data Date: Wed, 16 Jan 2019 16:54:33 +0000 Message-ID: <99e03a7e-2a5c-5f8f-5a16-e01088c59fff@arm.com> References: <20190108102633.17482-1-eric.auger@redhat.com> <20190108102633.17482-15-eric.auger@redhat.com> <20190110104544.26f3bcb1@jacob-builder> <63a19100-c3dd-9dbd-b37a-9dfbe254459e@arm.com> <07fc2059-3a4e-6b36-262b-779eb98b2334@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <07fc2059-3a4e-6b36-262b-779eb98b2334@redhat.com> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu To: Auger Eric , Jacob Pan Cc: "kevin.tian@intel.com" , "alex.williamson@redhat.com" , "ashok.raj@intel.com" , "kvm@vger.kernel.org" , "yi.l.liu@linux.intel.com" , Marc Zyngier , Will Deacon , "linux-kernel@vger.kernel.org" , "iommu@lists.linux-foundation.org" , Robin Murphy , "kvmarm@lists.cs.columbia.edu" , "eric.auger.pro@gmail.com" List-Id: iommu@lists.linux-foundation.org On 15/01/2019 21:27, Auger Eric wrote: [...] >>>> /* iommu fault flags */ >>>> -#define IOMMU_FAULT_READ 0x0 >>>> -#define IOMMU_FAULT_WRITE 0x1 >>>> +#define IOMMU_FAULT_READ (1 << 0) >>>> +#define IOMMU_FAULT_WRITE (1 << 1) >>>> +#define IOMMU_FAULT_EXEC (1 << 2) >>>> +#define IOMMU_FAULT_PRIV (1 << 3) >>>> >>>> typedef int (*iommu_fault_handler_t)(struct iommu_domain *, >>>> struct device *, unsigned long, int, void *); >>>> +typedef int (*iommu_dev_fault_handler_t)(struct iommu_fault_event *, >>>> void *); >>>> struct iommu_domain_geometry { >>>> dma_addr_t aperture_start; /* First address that can be >>>> mapped */ @@ -255,6 +259,52 @@ struct iommu_device { >>>> struct device *dev; >>>> }; >>>> >>>> +/** >>>> + * struct iommu_fault_event - Generic per device fault data >>>> + * >>>> + * - PCI and non-PCI devices >>>> + * - Recoverable faults (e.g. page request), information based on >>>> PCI ATS >>>> + * and PASID spec. >>>> + * - Un-recoverable faults of device interest >>>> + * - DMA remapping and IRQ remapping faults >>>> + * >>>> + * @fault: fault descriptor >>>> + * @device_private: if present, uniquely identify device-specific >>>> + * private data for an individual page request. >>>> + * @iommu_private: used by the IOMMU driver for storing >>>> fault-specific >>>> + * data. Users should not modify this field before >>>> + * sending the fault response. >>>> + */ >>>> +struct iommu_fault_event { >>>> + struct iommu_fault fault; >>>> + u64 device_private; >>> I think we want to move device_private to uapi since it gets injected >>> into the guest, then returned by guest in case of page response. For >>> VT-d we also need 128 bits of private data. VT-d spec. 7.7.1 >> >> Ah, I didn't notice the format changed in VT-d rev3. On that topic, how >> do we manage future extensions to the iommu_fault struct? Should we add >> ~48 bytes of padding after device_private, along with some flags telling >> which field is valid, or deal with it using a structure version like we >> do for the invalidate and bind structs? In the first case, iommu_fault >> wouldn't fit in a 64-byte cacheline anymore, but I'm not sure we care. >> >>> For exception tracking (e.g. unanswered page request), I can add timer >>> and list info later when I include PRQ. sounds ok? >>>> + u64 iommu_private; >> [...] >>>> +/** >>>> + * struct iommu_fault - Generic fault data >>>> + * >>>> + * @type contains fault type >>>> + * @reason fault reasons if relevant outside IOMMU driver. >>>> + * IOMMU driver internal faults are not reported. >>>> + * @addr: tells the offending page address >>>> + * @fetch_addr: tells the address that caused an abort, if any >>>> + * @pasid: contains process address space ID, used in shared virtual >>>> memory >>>> + * @page_req_group_id: page request group index >>>> + * @last_req: last request in a page request group >>>> + * @pasid_valid: indicates if the PRQ has a valid PASID >>>> + * @prot: page access protection flag: >>>> + * IOMMU_FAULT_READ, IOMMU_FAULT_WRITE >>>> + */ >>>> + >>>> +struct iommu_fault { >>>> + __u32 type; /* enum iommu_fault_type */ >>>> + __u32 reason; /* enum iommu_fault_reason */ >>>> + __u64 addr; >>>> + __u64 fetch_addr; >>>> + __u32 pasid; >>>> + __u32 page_req_group_id; >>>> + __u32 last_req; >>>> + __u32 pasid_valid; >>>> + __u32 prot; >>>> + __u32 access; >> >> What does @access contain? Can it be squashed into @prot? > it was related to F_ACCESS event record and was a placeholder for > reporting access attributes of the input transaction (Rnw, InD, PnU > fields). But I wonder whether this is needed to implement such fine > level fault reporting. Do we really care? I think we do, to properly inject PRI/Stall later. But RnW, InD and PnU can already be described with the IOMMU_FAULT_* flags defined above. We're missing CLASS and S2, which could also be useful for debugging. CLASS is specific to SMMUv3 but could probably be represented with @reason. For S2, we could keep printing stage-2 faults in the driver, and not report them to userspace. Thanks, Jean