Messages in this thread | | | Subject | Re: [PATCH v5 01/14] iommu: Add dma ownership management interfaces | From | Lu Baolu <> | Date | Wed, 5 Jan 2022 14:57:54 +0800 |
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Hi Christoph,
On 1/4/22 6:08 PM, Christoph Hellwig wrote: > On Tue, Jan 04, 2022 at 09:56:31AM +0800, Lu Baolu wrote: >> Multiple devices may be placed in the same IOMMU group because they >> cannot be isolated from each other. These devices must either be >> entirely under kernel control or userspace control, never a mixture. >> >> This adds dma ownership management in iommu core and exposes several >> interfaces for the device drivers and the device userspace assignment >> framework (i.e. vfio), so that any conflict between user and kernel >> controlled DMA could be detected at the beginning. >> >> The device driver oriented interfaces are, >> >> int iommu_device_use_dma_api(struct device *dev); >> void iommu_device_unuse_dma_api(struct device *dev); >> >> Devices under kernel drivers control must call iommu_device_use_dma_api() >> before driver probes. The driver binding process must be aborted if it >> returns failure. >> >> The vfio oriented interfaces are, >> >> int iommu_group_set_dma_owner(struct iommu_group *group, >> void *owner); >> void iommu_group_release_dma_owner(struct iommu_group *group); >> bool iommu_group_dma_owner_claimed(struct iommu_group *group); >> >> The device userspace assignment must be disallowed if the set dma owner >> interface returns failure. >> >> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> >> Signed-off-by: Kevin Tian <kevin.tian@intel.com> >> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> >> --- >> include/linux/iommu.h | 31 ++++++++ >> drivers/iommu/iommu.c | 161 +++++++++++++++++++++++++++++++++++++++++- >> 2 files changed, 189 insertions(+), 3 deletions(-) >> >> diff --git a/include/linux/iommu.h b/include/linux/iommu.h >> index de0c57a567c8..568f285468cf 100644 >> --- a/include/linux/iommu.h >> +++ b/include/linux/iommu.h >> @@ -682,6 +682,13 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, >> void iommu_sva_unbind_device(struct iommu_sva *handle); >> u32 iommu_sva_get_pasid(struct iommu_sva *handle); >> >> +int iommu_device_use_dma_api(struct device *dev); >> +void iommu_device_unuse_dma_api(struct device *dev); >> + >> +int iommu_group_set_dma_owner(struct iommu_group *group, void *owner); >> +void iommu_group_release_dma_owner(struct iommu_group *group); >> +bool iommu_group_dma_owner_claimed(struct iommu_group *group); >> + >> #else /* CONFIG_IOMMU_API */ >> >> struct iommu_ops {}; >> @@ -1082,6 +1089,30 @@ static inline struct iommu_fwspec *dev_iommu_fwspec_get(struct device *dev) >> { >> return NULL; >> } >> + >> +static inline int iommu_device_use_dma_api(struct device *dev) >> +{ >> + return 0; >> +} >> + >> +static inline void iommu_device_unuse_dma_api(struct device *dev) >> +{ >> +} >> + >> +static inline int >> +iommu_group_set_dma_owner(struct iommu_group *group, void *owner) >> +{ >> + return -ENODEV; >> +} >> + >> +static inline void iommu_group_release_dma_owner(struct iommu_group *group) >> +{ >> +} >> + >> +static inline bool iommu_group_dma_owner_claimed(struct iommu_group *group) >> +{ >> + return false; >> +} >> #endif /* CONFIG_IOMMU_API */ >> >> /** >> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c >> index 8b86406b7162..ff0c8c1ad5af 100644 >> --- a/drivers/iommu/iommu.c >> +++ b/drivers/iommu/iommu.c >> @@ -48,6 +48,8 @@ struct iommu_group { >> struct iommu_domain *default_domain; >> struct iommu_domain *domain; >> struct list_head entry; >> + unsigned int owner_cnt; >> + void *owner; >> }; >> >> struct group_device { >> @@ -289,7 +291,12 @@ int iommu_probe_device(struct device *dev) >> mutex_lock(&group->mutex); >> iommu_alloc_default_domain(group, dev); >> >> - if (group->default_domain) { >> + /* >> + * If device joined an existing group which has been claimed >> + * for none kernel DMA purpose, avoid attaching the default >> + * domain. >> + */ >> + if (group->default_domain && !group->owner) { >> ret = __iommu_attach_device(group->default_domain, dev); >> if (ret) { >> mutex_unlock(&group->mutex); >> @@ -2320,7 +2327,7 @@ static int __iommu_attach_group(struct iommu_domain *domain, >> { >> int ret; >> >> - if (group->default_domain && group->domain != group->default_domain) >> + if (group->domain && group->domain != group->default_domain) >> return -EBUSY; >> >> ret = __iommu_group_for_each_dev(group, domain, >> @@ -2357,7 +2364,11 @@ static void __iommu_detach_group(struct iommu_domain *domain, >> { >> int ret; >> >> - if (!group->default_domain) { >> + /* >> + * If group has been claimed for none kernel DMA purpose, avoid >> + * re-attaching the default domain. >> + */ > > none kernel reads odd. But maybe drop that and just say 'claimed > already' ala: > > /* > * If the group has been claimed already, do not re-attach the default > * domain. > */ >
Sure!
Best regards, baolu
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