Messages in this thread | | | Date | Mon, 21 Mar 2022 18:27:37 +0800 | Subject | Re: [PATCH RFC 03/11] iommu: Add attach/detach_dev_pasid domain ops | From | Lu Baolu <> |
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On 2022/3/21 15:13, Tian, Kevin wrote: >> From: Lu Baolu<baolu.lu@linux.intel.com> >> Sent: Sunday, March 20, 2022 2:40 PM >> >> Attaching an IOMMU domain to a PASID of a device is a generic operation >> for modern IOMMU drivers which support PASID-granular DMA address >> translation. Currently visible usage scenarios include (but not limited): >> >> - SVA >> - kernel DMA with PASID >> - hardware-assist mediated device >> >> This adds a pair of common domain ops for this purpose and implements a >> couple of wrapper helpers for in-kernel usage. >> >> Signed-off-by: Lu Baolu<baolu.lu@linux.intel.com> >> --- >> include/linux/iommu.h | 22 ++++++++++++++++++++++ >> drivers/iommu/iommu.c | 41 >> +++++++++++++++++++++++++++++++++++++++++ >> 2 files changed, 63 insertions(+) >> >> diff --git a/include/linux/iommu.h b/include/linux/iommu.h >> index 3e179b853380..e51845b9a146 100644 >> --- a/include/linux/iommu.h >> +++ b/include/linux/iommu.h >> @@ -268,6 +268,8 @@ struct iommu_ops { >> * struct iommu_domain_ops - domain specific operations >> * @attach_dev: attach an iommu domain to a device >> * @detach_dev: detach an iommu domain from a device >> + * @attach_dev_pasid: attach an iommu domain to a pasid of device >> + * @detach_dev_pasid: detach an iommu domain from a pasid of device >> * @map: map a physically contiguous memory region to an iommu domain >> * @map_pages: map a physically contiguous set of pages of the same size >> to >> * an iommu domain. >> @@ -285,6 +287,10 @@ struct iommu_ops { >> struct iommu_domain_ops { >> int (*attach_dev)(struct iommu_domain *domain, struct device *dev); >> void (*detach_dev)(struct iommu_domain *domain, struct device >> *dev); >> + int (*attach_dev_pasid)(struct iommu_domain *domain, >> + struct device *dev, ioasid_t id); >> + void (*detach_dev_pasid)(struct iommu_domain *domain, >> + struct device *dev, ioasid_t id); >> >> int (*map)(struct iommu_domain *domain, unsigned long iova, >> phys_addr_t paddr, size_t size, int prot, gfp_t gfp); >> @@ -678,6 +684,11 @@ int iommu_group_claim_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); >> >> +int iommu_attach_device_pasid(struct iommu_domain *domain, >> + struct device *dev, ioasid_t pasid); >> +void iommu_detach_device_pasid(struct iommu_domain *domain, >> + struct device *dev, ioasid_t pasid); >> + >> #else /* CONFIG_IOMMU_API */ >> >> struct iommu_ops {}; >> @@ -1046,6 +1057,17 @@ static inline bool >> iommu_group_dma_owner_claimed(struct iommu_group *group) >> { >> return false; >> } >> + >> +static inline int iommu_attach_device_pasid(struct iommu_domain >> *domain, >> + struct device *dev, ioasid_t pasid) >> +{ >> + return -ENODEV; >> +} >> + >> +static inline void iommu_detach_device_pasid(struct iommu_domain >> *domain, >> + struct device *dev, ioasid_t pasid) >> +{ >> +} >> #endif /* CONFIG_IOMMU_API */ >> >> /** >> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c >> index 0c42ece25854..78c71ee15f36 100644 >> --- a/drivers/iommu/iommu.c >> +++ b/drivers/iommu/iommu.c >> @@ -3167,3 +3167,44 @@ bool iommu_group_dma_owner_claimed(struct >> iommu_group *group) >> return user; >> } >> EXPORT_SYMBOL_GPL(iommu_group_dma_owner_claimed); >> + >> +int iommu_attach_device_pasid(struct iommu_domain *domain, >> + struct device *dev, ioasid_t pasid) >> +{ >> + struct iommu_group *group; >> + int ret = -EINVAL; >> + >> + if (!domain->ops->attach_dev_pasid) >> + return -EINVAL; >> + >> + group = iommu_group_get(dev); >> + if (!group) >> + return -ENODEV; >> + >> + mutex_lock(&group->mutex); >> + if (iommu_group_device_count(group) != 1) >> + goto out_unlock; > Need move the reason of above limitation from iommu_sva_bind_device() > to here: > > /* > * To keep things simple, SVA currently doesn't support IOMMU groups > * with more than one device. Existing SVA-capable systems are not > * affected by the problems that required IOMMU groups (lack of ACS > * isolation, device ID aliasing and other hardware issues). > */ > if (iommu_group_device_count(group) != 1) > goto out_unlock;
Yes. We need a comment around this code. But it's not only for SVA but also for all pasid attachment feature. I need more inputs to judge whether this limitation is reasonable.
> > btw I didn't see any safeguard on above assumption in device hotplug path > to a group which already has SVA enabled... >
Agreed.
Best regards, baolu
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