Re: [RFC PATCH v2 1/6] iommu: Evolve to support more scenarios of using IOPF
From: Shenming Lu <hidden>
Date: 2021-03-10 06:35:51
Also in:
kvm, linux-arm-kernel, linux-iommu, lkml
Hi Baolu, On 2021/3/10 10:09, Lu Baolu wrote:
Hi Shenming, On 3/9/21 2:22 PM, Shenming Lu wrote:quoted
This patch follows the discussion here: https://lore.kernel.org/linux-acpi/YAaxjmJW+ZMvrhac@myrica/ (local) In order to support more scenarios of using IOPF (mainly consider the nested extension), besides keeping IOMMU_DEV_FEAT_IOPF as a general capability for whether delivering faults through the IOMMU, we extend iommu_register_fault_handler() with flags and introduce IOPF_REPORT_FLAT and IOPF_REPORT_NESTED to describe the page fault reporting capability under a specific configuration. IOPF_REPORT_NESTED needs additional info to indicate which level/stage is concerned since the fault client may be interested in only one level. Signed-off-by: Shenming Lu <redacted> --- .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 3 +- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 11 ++-- drivers/iommu/io-pgfault.c | 4 -- drivers/iommu/iommu.c | 56 ++++++++++++++++++- include/linux/iommu.h | 21 ++++++- include/uapi/linux/iommu.h | 3 + 6 files changed, 85 insertions(+), 13 deletions(-)diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c index ee66d1f4cb81..5de9432349d4 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c@@ -482,7 +482,8 @@ static int arm_smmu_master_sva_enable_iopf(struct arm_smmu_master *master)if (ret) return ret; - ret = iommu_register_device_fault_handler(dev, iommu_queue_iopf, dev); + ret = iommu_register_device_fault_handler(dev, iommu_queue_iopf, + IOPF_REPORT_FLAT, dev); if (ret) { iopf_queue_remove_device(master->smmu->evtq.iopf, dev); return ret;diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c index 363744df8d51..f40529d0075d 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c@@ -1447,10 +1447,6 @@ static int arm_smmu_handle_evt(struct arm_smmu_device *smmu, u64 *evt)return -EOPNOTSUPP; } - /* Stage-2 is always pinned at the moment */ - if (evt[1] & EVTQ_1_S2) - return -EFAULT; - if (evt[1] & EVTQ_1_RnW) perm |= IOMMU_FAULT_PERM_READ; else@@ -1468,13 +1464,18 @@ static int arm_smmu_handle_evt(struct arm_smmu_device *smmu, u64 *evt).flags = IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE, .grpid = FIELD_GET(EVTQ_1_STAG, evt[1]), .perm = perm, - .addr = FIELD_GET(EVTQ_2_ADDR, evt[2]), }; if (ssid_valid) { flt->prm.flags |= IOMMU_FAULT_PAGE_REQUEST_PASID_VALID; flt->prm.pasid = FIELD_GET(EVTQ_0_SSID, evt[0]); } + + if (evt[1] & EVTQ_1_S2) { + flt->prm.flags |= IOMMU_FAULT_PAGE_REQUEST_L2; + flt->prm.addr = FIELD_GET(EVTQ_3_IPA, evt[3]); + } else + flt->prm.addr = FIELD_GET(EVTQ_2_ADDR, evt[2]); } else { flt->type = IOMMU_FAULT_DMA_UNRECOV; flt->event = (struct iommu_fault_unrecoverable) {diff --git a/drivers/iommu/io-pgfault.c b/drivers/iommu/io-pgfault.c index 1df8c1dcae77..abf16e06bcf5 100644 --- a/drivers/iommu/io-pgfault.c +++ b/drivers/iommu/io-pgfault.c@@ -195,10 +195,6 @@ int iommu_queue_iopf(struct iommu_fault *fault, void *cookie)lockdep_assert_held(¶m->lock); - if (fault->type != IOMMU_FAULT_PAGE_REQ) - /* Not a recoverable page fault */ - return -EOPNOTSUPP; -Any reasons why do you want to remove this check?
My thought was to make the reporting cap more detailed: IOPF_REPORT_ is only for recoverable page faults (IOMMU_FAULT_PAGE_REQ), and we may add UNRECOV_FAULT_REPORT_ later for unrecoverable faults (IOMMU_FAULT_DMA_UNRECOV)...
quoted
/* * As long as we're holding param->lock, the queue can't be unlinked * from the device and therefore cannot disappear.diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index d0b0a15dba84..cb1d93b00f7d 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c@@ -1056,6 +1056,40 @@ int iommu_group_unregister_notifier(struct iommu_group *group,} EXPORT_SYMBOL_GPL(iommu_group_unregister_notifier); +/* + * iommu_update_device_fault_handler - Update the device fault handler via flags + * @dev: the device + * @mask: bits(not set) to clear + * @set: bits to set + * + * Update the device fault handler installed by + * iommu_register_device_fault_handler(). + * + * Return 0 on success, or an error. + */ +int iommu_update_device_fault_handler(struct device *dev, u32 mask, u32 set) +{ + struct dev_iommu *param = dev->iommu; + int ret = 0; + + if (!param) + return -EINVAL; + + mutex_lock(¶m->lock); + + if (param->fault_param) { + ret = -EINVAL; + goto out_unlock; + } + + param->fault_param->flags = (param->fault_param->flags & mask) | set; + +out_unlock: + mutex_unlock(¶m->lock); + return ret; +} +EXPORT_SYMBOL_GPL(iommu_update_device_fault_handler);When and why will this API be used? Why not registering the fault handling capabilities of a device driver only once during probe()?
In VFIO, stage 2 IOPF might be enabled via an ioctl from the userspace (in this series), while stage 1 IOPF is enabled from vfio_pci_enable() [1] for nested mode, they are configured separately, and currently each device can only have one iommu dev fault handler. So I choose to add a update interface for the second one. [1] https://patchwork.kernel.org/project/kvm/patch/20210223210625.604517-6-eric.auger@redhat.com/
quoted
+ /** * iommu_register_device_fault_handler() - Register a device fault handler * @dev: the device@@ -1076,11 +1110,14 @@ EXPORT_SYMBOL_GPL(iommu_group_unregister_notifier);*/ int iommu_register_device_fault_handler(struct device *dev, iommu_dev_fault_handler_t handler, - void *data) + u32 flags, void *data) { struct dev_iommu *param = dev->iommu; int ret = 0; + if (flags & IOPF_REPORT_FLAT && flags & IOPF_REPORT_NESTED) + return -EINVAL; + if (!param) return -EINVAL; @@ -1099,6 +1136,7 @@ int iommu_register_device_fault_handler(struct device *dev, goto done_unlock; } param->fault_param->handler = handler; + param->fault_param->flags = flags; param->fault_param->data = data; mutex_init(¶m->fault_param->lock); INIT_LIST_HEAD(¶m->fault_param->faults);@@ -1177,6 +1215,22 @@ int iommu_report_device_fault(struct device *dev, struct iommu_fault_event *evt)goto done_unlock; } + /* The unrecoverable fault reporting is not supported at the moment. */ + if (evt->fault.type != IOMMU_FAULT_PAGE_REQ) + return -EOPNOTSUPP;Any reasons why do you want to disable reporting an unrecoverable fault?
When I add UNRECOV_FAULT_REPORT_ (mentioned above), I will enable the unrecoverable fault reporting if the fault client concerns it. Sorry for this. :-)
quoted
+ + if (evt->fault.type == IOMMU_FAULT_PAGE_REQ) { + if (fparam->flags & IOPF_REPORT_NESTED) { + if (evt->fault.prm.flags & IOMMU_FAULT_PAGE_REQUEST_L2 && + !(fparam->flags & IOPF_REPORT_NESTED_L2_CONCERNED)) + return -EOPNOTSUPP; + if (!(evt->fault.prm.flags & IOMMU_FAULT_PAGE_REQUEST_L2) && + !(fparam->flags & IOPF_REPORT_NESTED_L1_CONCERNED)) + return -EOPNOTSUPP; + } else if (!(fparam->flags & IOPF_REPORT_FLAT)) + return -EOPNOTSUPP; + } + if (evt->fault.type == IOMMU_FAULT_PAGE_REQ && (evt->fault.prm.flags & IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE)) { evt_pending = kmemdup(evt, sizeof(struct iommu_fault_event),diff --git a/include/linux/iommu.h b/include/linux/iommu.h index 86d688c4418f..f03d761e8310 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h@@ -352,12 +352,21 @@ struct iommu_fault_event {/** * struct iommu_fault_param - per-device IOMMU fault data * @handler: Callback function to handle IOMMU faults at device level + * @flags: Indicates whether the fault reporting is available under a + * specific configuration (1st/2nd-level-only(FLAT), or nested). + * IOPF_REPORT_NESTED needs to additionally know which level/stage + * is concerned.If IOPF_REPORT_NESTED only is not valid why do you want to define it?
Yeah, it seems that IOPF_REPORT_NESTED is unnecessary, IOPF_REPORT_NESTED_L1 + IOPF_REPORT_NESTED_L2 is enough... Thanks for your comments! Shenming
quoted
* @data: handler private data * @faults: holds the pending faults which needs response * @lock: protect pending faults list */ struct iommu_fault_param { iommu_dev_fault_handler_t handler; +#define IOPF_REPORT_FLAT (1 << 0) +#define IOPF_REPORT_NESTED (1 << 1) +#define IOPF_REPORT_NESTED_L1_CONCERNED (1 << 2) +#define IOPF_REPORT_NESTED_L2_CONCERNED (1 << 3) + u32 flags; void *data; struct list_head faults; struct mutex lock;@@ -509,9 +518,11 @@ extern int iommu_group_register_notifier(struct iommu_group *group,struct notifier_block *nb); extern int iommu_group_unregister_notifier(struct iommu_group *group, struct notifier_block *nb); +extern int iommu_update_device_fault_handler(struct device *dev, + u32 mask, u32 set); extern int iommu_register_device_fault_handler(struct device *dev, iommu_dev_fault_handler_t handler, - void *data); + u32 flags, void *data); extern int iommu_unregister_device_fault_handler(struct device *dev); @@ -873,10 +884,16 @@ static inline int iommu_group_unregister_notifier(struct iommu_group *group, return 0; } +static inline int iommu_update_device_fault_handler(struct device *dev, + u32 mask, u32 set) +{ + return -ENODEV; +} + static inline int iommu_register_device_fault_handler(struct device *dev, iommu_dev_fault_handler_t handler, - void *data) + u32 flags, void *data) { return -ENODEV; }diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h index e1d9e75f2c94..0ce0dfb7713e 100644 --- a/include/uapi/linux/iommu.h +++ b/include/uapi/linux/iommu.h@@ -85,6 +85,8 @@ struct iommu_fault_unrecoverable {* When IOMMU_FAULT_PAGE_RESPONSE_NEEDS_PASID is set, the page response * must have the same PASID value as the page request. When it is clear, * the page response should not have a PASID. + * If IOMMU_FAULT_PAGE_REQUEST_L2 is set, the fault occurred at the + * second level/stage, otherwise, occurred at the first level. * @pasid: Process Address Space ID * @grpid: Page Request Group Index * @perm: requested page permissions (IOMMU_FAULT_PERM_* values)@@ -96,6 +98,7 @@ struct iommu_fault_page_request {#define IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE (1 << 1) #define IOMMU_FAULT_PAGE_REQUEST_PRIV_DATA (1 << 2) #define IOMMU_FAULT_PAGE_RESPONSE_NEEDS_PASID (1 << 3) +#define IOMMU_FAULT_PAGE_REQUEST_L2 (1 << 4) __u32 flags; __u32 pasid; __u32 grpid;Best regards, baolu .