Messages in this thread | | | Subject | Re: [PATCH v1 1/8] iommu: Add iommu_group_replace_domain() | From | Lu Baolu <> | Date | Fri, 7 Jan 2022 08:26:50 +0800 |
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On 1/7/22 1:06 AM, Jason Gunthorpe wrote: > On Thu, Jan 06, 2022 at 10:20:46AM +0800, Lu Baolu wrote: >> Expose an interface to replace the domain of an iommu group for frameworks >> like vfio which claims the ownership of the whole iommu group. >> >> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> >> include/linux/iommu.h | 10 ++++++++++ >> drivers/iommu/iommu.c | 37 +++++++++++++++++++++++++++++++++++++ >> 2 files changed, 47 insertions(+) >> >> diff --git a/include/linux/iommu.h b/include/linux/iommu.h >> index 408a6d2b3034..66ebce3d1e11 100644 >> +++ b/include/linux/iommu.h >> @@ -677,6 +677,9 @@ 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); >> +int iommu_group_replace_domain(struct iommu_group *group, >> + struct iommu_domain *old, >> + struct iommu_domain *new); >> >> #else /* CONFIG_IOMMU_API */ >> >> @@ -1090,6 +1093,13 @@ static inline bool iommu_group_dma_owner_claimed(struct iommu_group *group) >> { >> return false; >> } >> + >> +static inline int >> +iommu_group_replace_domain(struct iommu_group *group, struct iommu_domain *old, >> + struct iommu_domain *new) >> +{ >> + return -ENODEV; >> +} >> #endif /* CONFIG_IOMMU_API */ >> >> /** >> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c >> index 72a95dea688e..ab8ab95969f5 100644 >> +++ b/drivers/iommu/iommu.c >> @@ -3431,3 +3431,40 @@ bool iommu_group_dma_owner_claimed(struct iommu_group *group) >> return user; >> } >> EXPORT_SYMBOL_GPL(iommu_group_dma_owner_claimed); >> + >> +/** >> + * iommu_group_replace_domain() - Replace group's domain >> + * @group: The group. >> + * @old: The previous attached domain. NULL for none. >> + * @new: The new domain about to be attached. >> + * >> + * This is to support backward compatibility for vfio which manages the dma >> + * ownership in iommu_group level. > > This should mention it can only be used with iommu_group_set_dma_owner()
Sure.
> >> + if (old) >> + __iommu_detach_group(old, group); >> + >> + if (new) { >> + ret = __iommu_attach_group(new, group); >> + if (ret && old) >> + __iommu_attach_group(old, group); >> + } > > The sketchy error unwind here gives me some pause for sure. Maybe we > should define that on error this leaves the domain as NULL > > Complicates vfio a tiny bit to cope with this failure but seems > cleaner than leaving it indeterminate.
Fair enough.
> > Jason >
Best regards, baolu
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